Description:TECHNICAL FIELD
The present disclosure relates to a field of construction materials. Moreover, the present disclosure relates to a three-dimensional (3D) printable construction material, a method of preparing the 3D-printable construction material, and a method of 3D-printing a construction element.
BACKGROUND
Recently, the construction industry is experiencing a shift towards automation, driven by worker shortages, productivity demands, and material wastage concerns, which is leading to the vast popularity of various automated construction techniques, such as additive manufacturing or three-dimensional (3D) printing. 3D-printing is a process of creating three-dimensional objects by adding layers of material in precise patterns to form complex shapes and structures. By layering materials to build structures, the 3D-printing offers precision in manufacturing building and infrastructural components and reduces material waste. However, conventional 3D-printable mixes contain substantially higher quantities of ordinary Portland cement and natural sand as compared to traditional concrete, which leads to an increased environmental impact as cement manufacturing contributes significantly to global carbon dioxide emissions. Moreover, the conventional 3D-printing methods that primarily use unstabilized natural soil exhibit limitations, including volumetric instability, crack formation, and compromised structural integrity, particularly during wet-dry cycles.
Certain advancements have been made to overcome the limitations posed by the conventional 3D-printing methods, such as incorporating the use of industrial byproducts like ground granulated blast furnace slag and fly ash and the use of earth-based 3D-printing materials like soil, mud, and the like to reduce environmental impact. While the earth-based 3D-printing has been done in full-scale 3D-printed structures, the earth-based 3D-printing still faces several challenges, such as poor rheological control, low print quality, and insufficient strength development. Additionally, the existing earth-based printable materials have only achieved compressive strengths of merely 0.73 to 3.0 megapascals (MPa), falling short of international construction standards. Moreover, the 3D-printed structures made from such 3D-printing materials exhibit weak inter-layer bonding, high porosity at layer interfaces, and significant shrinkage issues. Thus, there exists a technical problem of how to develop a 3D printable construction material with optimal rheological properties, improved inter-layer bonding, reduced shrinkage, and enhanced moisture resistance.
Therefore, in light of the foregoing discussion, there exists a need to overcome the aforementioned drawbacks associated with the existing three-dimensional printable material and the existing methods for improved print quality and structural quality.
SUMMARY
The present disclosure provides a three-dimensional (3D) printable construction material, a method of preparing the 3D-printable construction material, and another method of 3D-printing a construction element. The present disclosure provides a solution to the technical problem of how to develop a 3D printable construction material with optimal rheological properties, improved inter-layer bonding, reduced shrinkage, and enhanced moisture resistance. The present disclosure aims to provide a solution that overcomes at least partially the problems encountered in the prior art and provides a composition that not only synthesizes 3D-printable construction materials that are cost-effective but also the method that may be easily adopted. Thus, the 3D-printable construction material, a method of preparing the 3D-printable construction material, and a method of 3D-printing of the construction element in the present disclosure exhibit technical advancement as well as economic benefits.
One or more objectives of the present disclosure is achieved by the solutions provided in the enclosed independent claims. Advantageous implementations of the present disclosure are further defined in the dependent claims.
In one aspect, the present disclosure provides a three-dimensional (3D) printable construction material, which includes one part of a binder comprising Portland cement. The 3D-printable construction material further includes two parts of fine aggregates comprising 25-50% by weight of excavated soil content containing non-expansive clay. Furthermore, the 3D-printable construction material includes a first chemical admixture in an amount of 0.10-0.36% by weight of the binder and a second chemical admixture in an amount of 0.46-2.75% by weight of the binder. Moreover, the 3D-printable construction material has a flow spread of 140-150 mm at first extrusion and is capable of being built up to a height of at least 1 meter when 3D-printed.
Advantageously, the 3D-printable construction material is configured to enhance the printability, structural stability, and environmental sustainability of the 3D-printed structures, such as by enhancing the overall strength and durability of 3D-printed structures. The addition of fine aggregates of materials, such as sand or finely crushed stone, combined with about 25 to 50% of excavated soil content containing non-expansive clay, makes the 3D-printable construction material both cost-effective and eco-friendly. Moreover, the utilization of non-expansive clay helps prevent shrinkage and cracking, thereby improving the stability of the 3D-printed structures. Furthermore, the precise combination of chemical admixtures, with the first admixture likely serving as a superplasticizer, provides a controlled flow spread of the 3D-printable construction material that is about 140-150 mm, thereby optimizing the workability and flow during extrusion of the 3D-printable construction material. The 3D-printable construction material further enables building the 3D-printed structures with a height of up to 1 meter or more without compromising the shape or form of the 3D-printed structure in order to provide a stable and high-performance 3D-printed construction.
In another aspect, the present disclosure provides a method of preparing the 3D-printable construction material, which includes collecting excavated soil content containing non-expansive clay from construction or demolition activities. The method of preparing the 3D-printable construction material further includes drying the excavated soil content to constant mass and sieving the dried soil. Furthermore, the method of preparing the 3D-printable construction material includes combining one part by weight of the binder comprising Portland cement and two parts by weight of the fine aggregates. The 25-50% by weight of the fine aggregates is the sieved excavated soil content. The method of preparing the 3D-printable construction material further includes combining the first chemical admixture in an amount of 0.10-0.36% by weight of the binder and the second chemical admixture in an amount of 0.46-2.75% by weight of the binder, and water in a water-to-binder ratio of 0.38-0.55. Moreover, the method of preparing the 3D-printable construction material includes mixing the combined ingredients to form the 3D-printable construction material having a flow spread of 140-150 mm at first extrusion. The 3D-printable construction material is capable of being built up to a height of at least 1 meter when 3D-printed.
The method achieves all the advantages and technical effects of the 3D-printed construction material of the present disclosure.
In yet another aspect, the present disclosure provides a method of 3D-printing a construction element comprising preparing a 3D-printable construction material by combining one part by weight of the binder comprising Portland cement and two parts by weight of the fine aggregates. The 25-50% by weight of the fine aggregates is excavated soil content containing non-expansive clay, the first chemical admixture in an amount of 0.10-0.36% by weight of the binder, the second chemical admixture in an amount of 0.46-2.75% by weight of the binder, and the water in a water-to-binder ratio of 0.38-0.55. The method of 3D-printing a construction element further includes mixing the combined ingredients to form the 3D-printable construction material having a flow spread of 140-150 mm at first extrusion. Furthermore, the method of 3D-printing a construction element includes extruding the 3D-printable construction material through a nozzle at a predefined rate, depositing layers according to a predetermined pattern at a layer height of 15-18 mm, and building up the layers to form the construction element to a height of at least 1 meter.
Advantageously, the method of 3D printing the construction element is used to optimize the preparation and application of the sustainable construction element, such as a mixture of excavated soil content, fly ash, GGBS, and the like. The method of 3D-printing the construction element includes blending the Portland cement, the excavated soil with non-expansive clay, and the chemical admixtures to provide the 3D-printing construction material with optimal strength and durability. The Portland cement is used as a strong binder, providing the rigidity and load-bearing capacity for structural stability of the 3D-printed structure. The use of the excavated soil content not only minimizes waste but also utilizes local resources, contributing to sustainability in construction practices. The chemical admixtures, including superplasticizers and viscosity modifiers, are used precisely to enhance the flow properties and extrusion control of the 3D-printable mixture. Furthermore, the method of 3D-printing the construction element includes a specific water-to-binder ratio of about 0.38 to 0.55 that provides a suitable consistency to the construction element for extrusion, providing smooth flow and reliable layer deposition. The method of preparing the 3D-printing construction element further includes the flow spread of about 140 to 150 mm during the initial extrusion, ensuring effective layering, while the predetermined pattern and layer height of about 15 to 18 mm enhances the accuracy and stability of the construction element. By allowing the construction element to reach a height of at least 1 meter, the method provides the development of durable 3D-printed structures and provides the suitability for modern construction needs while focusing on environmental responsibility.
It is to be appreciated that all the implementation forms can be combined. All steps that are performed by the various entities described in the present application as well as the functionalities described to be performed by the various entities are intended to mean that the respective entity is adapted to or configured to perform the respective steps and functionalities. It will be appreciated that features of the present disclosure are susceptible to being combined in various combinations without departing from the scope of the present disclosure as defined by the appended claims.
Additional aspects, advantages, features, and objects of the present disclosure would be made apparent from the drawings and the detailed description of the illustrative implementations are construed in conjunction with the appended claims that follow.
BRIEF DESCRIPTION OF THE DRAWINGS
The summary above, as well as the following detailed description of illustrative embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the present disclosure, exemplary constructions of the disclosure are shown in the drawings. However, the present disclosure is not limited to specific methods and instrumentalities disclosed herein. Moreover, those skilled in the art will understand that the drawings are not to scale. Wherever possible, like elements have been indicated by identical numbers.
Embodiments of the present disclosure will now be described, by way of example only, with reference to the following diagrams wherein:
FIG.1 depicts a flowchart illustrating a method for preparing a 3D-printable construction material, in accordance with an embodiment of the present disclosure;
FIG.2 depicts a flowchart illustrating a method of 3D-printing a construction element, in accordance with an embodiment of the present disclosure;
FIG. 3A depicts an exemplary diagram of a hollow cuboid 3D-printed structure that is prepared using 3D-printable construction material, in accordance with an embodiment of the present disclosure;
FIG. 3B depicts another exemplary diagram of the hollow cuboid 3D-printed structure that is prepared using 3D printable construction material, in accordance with an embodiment of the present disclosure;
FIGs. 4A and 4B depict the graphical representations that illustrate filament width and Shape retention factor (SRF) for different compositions under varying testing conditions, in accordance with an embodiment of the present disclosure;
FIG. 5 depicts the graphical representation that illustrates the rheological properties of different compositions through apparent viscosity, in accordance with an embodiment of the present disclosure;
FIG. 6 depicts a graphical representation that illustrates the mechanical properties of different compositions through dynamic yield stress, in accordance with an embodiment of the present disclosure;
FIGs. 7A and 7B depict Scanning Electron Microscopy (SEM) images of Ordinary Portland Cement (OPC) and Ground Granulated Blast-furnace Slag (GGBS), in accordance with an embodiment of the present disclosure;
FIGs. 8A and 8B depict the graphical representations that illustrate the plastic viscosity of two different set of compositions, in accordance with an embodiment of the present disclosure;
FIGs. 9A and 9B depict the graphical representations that illustrate flow retention characteristics of different compositions over the printing duration, in accordance with an embodiment of the present disclosure;
FIG. 10 depicts the graphical representation that illustrates the change in viscosity of three different compositions across different intervals of time, in accordance with an embodiment of the present disclosure;
FIG. 11 depicts the graphical representation that illustrates the recovery in viscosity for various compositions, in accordance with an embodiment of the present disclosure;
FIG. 12 depicts a pictorial representation of the 3D-printed structures formed by 3D-printing the 3D-printable construction material, in accordance with the present disclosure;
FIG. 13 depicts a schematic representation illustrating the extraction of composition from 3D-printed strips through a wet cutting method, in accordance with the present disclosure;
FIGs. 14A, 14B, 14C and 14D depict the graphical representations that illustrate mechanical properties of various compositions under three loading directions, in accordance with an embodiment of the present disclosure;
FIGs. 15A and 15B depict the graphical representations illustrate total shrinkage behavior of different compositions over time, in accordance with an embodiment of the present disclosure;
FIGs. 16A and 16B depict the graphical representations that illustrate inter-layer bond strength of different compositions tested in two loading directions L1 and L2, in accordance with an embodiment of the present disclosure;
FIG. 17 depicts an exemplary diagram that illustrates a sequence of execution for a process of developing and printing 3D-printable construction material, in accordance with an embodiment of the present disclosure; and
FIGs. 18A and 18B depict the graphical representation that illustrates the relationship between the static yield stress of the various compositions and the duration from the start of 3D printing, in accordance with an embodiment of the present disclosure.
In the accompanying drawings, an underlined number is employed to represent an item over which the underlined number is positioned or an item to which the underlined number is adjacent. A non-underlined number relates to an item identified by a line linking the non-underlined number to the item. When a number is non-underlined and accompanied by an associated arrow, the non-underlined number is used to identify a general item at which the arrow is pointing.
DETAILED DESCRIPTION OF EMBODIMENTS
The following detailed description illustrates embodiments of the present disclosure and ways in which they can be implemented. Although some modes of carrying out the present disclosure have been disclosed, those skilled in the art would recognize that other embodiments for carrying out or practicing the present disclosure are also possible.
FIG.1 depicts a flowchart illustrating a method for preparing a 3D-printable construction material, in accordance with an embodiment of the present disclosure. With reference to FIG. 1, there is shown a flowchart illustrating the method 100 for preparing the 3D-printable construction material. The method 100 includes steps 102 to 110.
There is provided the method 100 for preparing the 3D-printable construction material. The 3D printable construction material includes excavated soil with a non-expansive clay content of about 42% to 47%. In an implementation, the method 100 utilizes lateritic soil, which is specifically sourced from excavation operations at a depth of more than 2 meters from topsoil. Moreover, the 3D printable construction material includes supplementary cementitious materials, including ground granulated blast furnace slag (GGBS) or fly ash, Portland cement, and manufactured sand (M-sand), which improve durability, strength, and workability of the 3D-printed structure, allowing the 3D-printed structure to withstand environmental and load bearing demands effectively. Additionally, the inclusion of materials like slag and fly ash contributes to sustainability by utilizing industrial by-products, reducing waste, and minimizing the embodied carbon associated with traditionally used construction materials. Furthermore, the 3D-printable construction material includes various chemical admixtures, including superplasticizers and viscosity modifiers in specific proportions, to enhance the flow properties and extrusion control during printing.
At step 102, the method 100 includes collecting the excavated soil content containing non-expansive clay from construction or demolition activities. The excavated soil content refers to the soil obtained from a depth greater than 2 meters below the topsoil, ensuring exclusion from organic matter contamination and consistent material properties. Moreover, the extensive testing of the collected excavated soil content confirms that the excavated soil contains no heavy metals, ensuring the safety of the 3D-printable construction material and validating the environmental compliance used in such construction applications. The collection of the excavated soil content includes identifying suitable construction or demolition sites where lateritic soil is present, as the lateritic soil contains approximately 42.50% clay content, which provides a better texture and viscous properties to the cementitious mixture. The natural viscosity-modifying properties of the clay content enable a 75% reduction in chemical additives compared to the conventional 3D-printing mixtures. Moreover, the excavated soil content contains alumina, silica, and ferric oxides, which provide viscosity and structural stability to the 3D-printable construction material and make the 3D-printable construction material well-suited as a partial replacement for fine aggregates of sand in cement-based construction materials. Additionally, the excavated soil content is configured to exhibit medium plasticity characteristics typical of loamy clay and is free from heavy metals. In an implementation, the collected excavated soil content samples are properly stored in covered areas to prevent contamination and reduce moisture absorption. The 3D-printable construction material with excavated soil content is then tested for shrinkage properties, as unstabilized clay grains are susceptible to volume changes that can affect the dimensional stability of the final 3D-printed structure. The liquid limit and plastic limit of the soil are also characterized because they influence the rheological properties of 3D printing. Moreover, the selection of the excavated soil content at step 102 directly impacts the final compressive strength, moisture sensitivity, and inter-layer bonding capabilities in the printed structure that ensures optimal performance in the 3D-printing process while contributing to reduced environmental impact through decreased consumption of Ordinary Portland Cement (OPC) and natural sand.
At step 104, the method 100 includes drying the excavated soil content to constant mass. Further, the excavated s at 60°C to remove any residual moisture that may affect the consistency and performance of the cementitious mixture. Further, the excavated soil is sieved through a 4.75 mm sieve to separate larger particles, yielding a particle fraction below 75µm that comprises fine clay and silt particles. In an implementation, the clay content of the excavated soil is determined as per the Indian standard such as, IS 2720-part 4, and IS 2720, part 5. In an implementation, the clay content found in the excavated soil content is 42.50%. Thus, the excavated soil content classifies as a loamy clay with medium plasticity. Additionally, the excavated soil content is dried at a temperature of about 60°C to eliminate any remaining moisture from the excavated soil.
At step 106, the method 100 includes sieving the dried soil (or the dried excavated soil). The dried excavated soil is sieved through a 4.75 mm sieve, which removes larger particles and isolates finer particles below 75 µm. The sieving process provides a finely graded material rich in silt and clay particles, essential for obtaining the intended viscosity and flow properties in the cementitious mixture. Thereby, the fine fraction of the excavated soil content enhances the buildability and workability of the 3D-printable mixture, which is essential for maintaining stable, smooth extrusion in 3D-printing applications.
At step 108, the method 100 includes combining one part by weight of binder comprising Portland cement and two parts by weight of fine aggregates. The 25-50% by the weight of the fine aggregates is the sieved soil content. The excavated soil is used as the partial replacement for M-sand (or manufactured sand) at 25% or 50% by weight, providing an added stability and viscosity to the cementitious mixture due to fine clay content. In an implementation, the M-sand can also be referred to as natural quarry sand. Furthermore, the cementitious mixture includes chemical admixtures including superplasticizers and viscosity-modifying agents (VMAs), to provide a balance of flow and workability. Furthermore, the chemical admixture contains a first chemical admixture at 0.10-0.36% by weight of the binder. In an example, the chemical admixtures contain the first chemical admixture at 0.10% by weight of the binder. In another example, the chemical admixtures contain the first chemical admixture at 0.36% by weight of the binder. In yet another example, the chemical admixture contains the first chemical admixture at 0.20% by weight of the binder. Furthermore, the chemical admixtures contain a second chemical admixture at 0.46-2.75% by weight of the binder, with water added to prepare a water-to-binder ratio of 0.38 - 0.55. In an example, the chemical admixtures contain the second chemical admixture at 0.46% by weight of the binder. In another example, the chemical admixture contains the second chemical admixture at 2.75% by weight of the binder. In yet another example, the chemical admixture contains the second chemical admixture at 1.25% by weight of the binder. In some implementations, the first chemical admixture may include but is not limited to the chemical admixture of polycarboxylate ethers (PCEs), lignosulfonates, naphthalene-based admixtures, and sulfonated melamine formaldehyde (SMF). In some other implementations, the second chemical admixture may include but is not limited to the chemical admixture of hydroxypropyl methylcellulose (HPMC), welan gum, xanthan gum, gellan gum, and carboxymethyl cellulose (CMC). In an implementation, the chemical admixtures are added to the water used for mixing, whereby the water to binder ratio is between 0.38 and 0.55. In another example, the water is added to the chemical admixture while maintaining the water to binder ratio of 0.45. Moreover, in cementitious mixtures containing excavated soil content, VMA dosage is reduced by 75% because the clay fraction naturally enhances viscosity, reducing the need for additional VMA. Thus, the combination of binder and fine aggregates provides the desired flow characteristics without compromising the stability of the excavated soil mixture, making the excavated soil mixture optimal for the extrusion process in 3D printing.
At step 110, the method 100 includes mixing the combined ingredients, including the binder (i.e., the Portland cement), fine aggregates (that includes manufactured sand (M-sand) and excavated soil content with non-expansive clay), to form the 3D-printable construction material having flow spread of 140-150 mm at first extrusion and capable of being built up to a height of at least 1 meter when 3D printed. The flow spreads, and the height is precisely calibrated to enable smooth, consistent extrusion, allowing the cementitious mixture to retain the shape of the 3D-printable construction material upon deposition while ensuring layer adhesion and build stability. Thus, attaining the required flow spread and height is essential for layer-by-layer construction of the 3D-printed structure and also ensures the mixture has sufficient plasticity without excessive reduction. In an implementation, while mixing the combined ingredients, including the binder (e.g., Portland cement), fine aggregates (that includes manufactured sand (M-sand) and excavated soil content with non-expansive clay), modifications in water content and superplasticizer dosage further refine the extrudability and flow retention of the cementitious mixture. Moreover, the excavated soil fraction contributes to the thixotropic properties, improving stability after extrusion and supporting the long-term integrity of the printed layers. Thus, the cementitious mixture enhances both the buildability and structural quality of a structure, ensuring the durability and stability of the 3D-printable construction material.
Advantageously, the method 100 for preparing the 3D-printable construction material enhances the printability, structural stability, and environmental sustainability of the 3D-printed structure, such as by enhancing the overall strength and durability of 3D-printed structures. The addition of fine aggregates of materials, such as sand or fine crushed stone, combined with about 25 to 50% of excavated soil content, containing non-expansive clay, makes the 3D-printable construction material both cost-effective and eco-friendly. Moreover, the utilization of the non-expansive clay helps prevent shrinkage and cracking, which improves the stability of the 3D-printed structures. Furthermore, the precise combination of the first and second chemical admixtures, with the first admixture likely serving as a superplasticizer, provides a controlled flow spread of the 3D-printable construction material that is about 140-150 mm, thereby optimizing the workability and flow during extrusion of the 3D-printable material. Additionally, the method 100 of preparing the 3D-printable construction material further enables to build the 3D-printed structures with a height of up to 1 meter or more without compromising shape or form in order to provide a stable and high-performance 3D-printed construction.
The steps 102 to 110 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
FIG.2 depicts a flowchart illustrating a method of 3D printing a construction element in accordance with an embodiment of the present disclosure. FIG. 2 is described in conjunction with FIG. 1. With reference to FIG. 2, there is shown the flowchart of the method 200. The method 200 includes steps 202 to 210.
There is provided the method 200 for 3D printing the construction element. The method 200 shows the 3D-printing the construction element, which includes the binder, the fine aggregates, the excavated soil content, and the like. The construction element further includes the chemical admixtures and water to provide the required consistency and flow properties for 3D-printing the construction element. In an implementation, the construction element (or the 3D-printable construction material) is extruded through the nozzle, with layers deposited in a controlled pattern to provide the desired shape and structural integrity of the 3D-printed structure.
At step 202, the method 200 includes preparing the 3D-printable construction material by combining one part by weight of the binder comprising the Portland cement, two parts by weight of the fine aggregates, including the manufactured sand (or M-sand) and the pre-treated excavated soil. The 3D-printable construction material is formed by combining one part by weight of the binder comprising the Portland cement, two parts by weight of the fine aggregates, the M-sand and the pre-treated excavated soil. The binder content is optimized to ensure the strength required for the structural integrity of the 3D-printed structure, while the combination of M-sand and the excavated soil is optimized to improve the flowability and workability of the 3D-printable construction element. The use of the excavated soil content as a partial replacement for M-sand (25–50%) in the cementitious mixture improves shape retention and stability of the 3D-printable construction element, attributed to the viscosity-modifying effects of the clay content in the excavated soil. In operation, the 3D-printable construction element is thoroughly mixed until a homogeneous blend is obtained, ensuring that the fine particles are well-dispersed throughout the cementitious mixture. In an implementation, the process of mixing is performed in a controlled environment to reduce excess moisture, which can negatively impact the consistency and printability of the 3D printable construction material. The first chemical admixture comprising a high-range polycarboxylate-based superplasticizer and cellulose ether-based viscosity modifier that further supports the extrudability, cohesiveness, and structural stability of the 3D printable mixture, which is essential to maintaining shape during extrusion. The controlled dosage of viscosity modifiers, especially in soil-containing cementitious mixtures, enhances the thixotropic properties of the cementitious mixture and minimizes material spread after extrusion. As a result, the fine balance of the binder, the fine aggregates in the excavated soil, and the viscosity modifiers ensure that the final cementitious mixture is homogeneous, with well-dispersed fine particles promoting uniformity in layer quality during the 3D-printing process.
At step 204, the method 200 includes mixing combined ingredients to form the 3D-printable construction material having a flow spread of 140-150 mm at first extrusion. The method 200 is configured to maintain a uniform consistency of the 3D-printable construction material, allowing the 3D-printable construction material to exhibit the desired rheological properties suitable for the 3D-printing. Preferably, the cellulose ether-based viscosity modifier in the compositions containing the excavated soil content is reduced by 75% due to the inherent thickening properties of the clay, while a high-range polycarboxylate superplasticizer (i.e., the first chemical admixture) is added to enhance the flow and extrudability of the 3D-printable construction material. In an implementation, the mixing of the elements, such as the binder, the fine aggregates in the excavated soil, and the chemical admixtures, is performed using specialized equipment to ensure thorough blending of the elements in the 3D-printable construction material. The blended 3D-printable construction material is then subjected to certain tests in order to confirm that the 3D printable construction material retains a flow spread of 140-150 mm at the first extrusion, which is essential for effective layer deposition.
At step 206, the method 200 includes extruding the 3D-printable construction material through the nozzle at a predefined rate. In an implementation, the nozzle with a nozzle size 20 mm, is chosen based on the maximum particle size (up to 5 mm) in the cementitious mixture, allowing for smooth flow of the 3D-printable material without any blockages. The nozzle stand-off distance is maintained between 16 – 18 mm, close to the designed 15 mm layer height, to support accurate layer formation and enhance the build quality of the 3D-printed structure. In an implementation, the printing of the 3D printable construction material further involves extrusion, which is performed using a screw extruder and a three-axis gantry printer, with periphery and infill printing speeds set to 30 mm/s and 60 mm/s, respectively. In operation, the extrudability of the 3D printable construction material is closely monitored to maintain a consistent rate that aligns with the printing speed, thereby ensuring uniform deposition of the 3D printable construction material onto the print bed.
At step 208, the method 200 includes depositing layers according to a predetermined pattern at a layer height of 15-16 mm. The layer height of about 15-16 mm provides optimal compaction and adhesion, ensuring stable bonding between layers and minimizing the risks of delamination of the layers. The predetermined pattern maximizes load-bearing capacity and minimizes material usage, supporting the creation of a strong and durable 3D-printed structure. In an implementation, the predefined patterns may include internal cross-bracings to increase the lateral stability of the 3D-printed structure. Thereby, the method 200 for preparing 3D-printing construction elements is configured to provide the desired geometry and structural integrity of the 3D-printed structure.
At step 210, the method 200 includes building up layers to form construction elements to a height of at least 1 meter. Each new layer of the 3D printable construction material is deposited on top of the prvious layer to ensure proper adhesion between the layers, thereby maintaining structural integrity of the 3D-printed structure as the height of the 3D-printed structure increases. Thus, the method 200 provides the 3D printed structure with a height of 1 meter or more, which confirms the effectiveness of both the material formulation and the 3D-printing process without the need for external formwork.
Advantageously, the method 200 of 3D-printing the construction element is configured to optimize the preparation and application of sustainable construction materials, such as the excavated soil, the fly ash, and the GGBS to ensures the efficiency and structural quality of the 3D-printed structure. The method 200 of printing the 3D-printing construction material includes blending the Portland cement, the excavated soil with non-expansive clay, and the chemical admixtures to prepare the 3D-printing construction material with optimal strength and durability. The Portland cement is used as a strong binder, providing the rigidity and load-bearing capacity for structural stability of the 3D-printed structures. The excavated soil present in the 3D-printing construction element as the sustainable construction materialnot only minimizes waste but also utilizes local resources, contributing to sustainability in 3D-printing of the 3D-printing construction element. The chemical admixtures, including superplasticizers and viscosity modifiers, are used precisely to enhance the flow properties and extrusion control of the 3D-printable construction element. Furthermore, the method 200 of the 3D-printing construction element includes a specific water-to-binder ratio of about 0.38 to 0.55 that provides a suitable consistency for extrusion, smooth flow and reliable layer deposition. Additionally, the method 200 of 3D-printing the construction element further includes the flow spread of about 140 to 150 mm during the initial extrusion, ensuring effective layering, while the predetermined pattern and layer height of about 15 to 18 mm enhances the accuracy and stability of the 3D-printable construction material. By allowing the 3D-printable construction material to reach a height of at least 1 meter, the method 200 provides the development of the durable 3D-printed structures and the suitability for modern construction needs while focusing on environmental responsibility.
The steps 202 to 210 are only illustrative, and other alternatives can also be provided where one or more steps are added, one or more steps are removed, or one or more steps are provided in a different sequence without departing from the scope of the claims herein.
FIG. 3A depicts an exemplary diagram of a hollow cuboid 3D-printed structure that is prepared using the 3D printable construction material, in accordance with an embodiment of the present disclosure. FIG. 3A is described in conjunction with FIG. 1 and FIG. 2. With reference to FIG. 3A, there is a shown diagram 300A that includes a hollow cuboid 3D-printed structure 302 that is layered in nature, where 302A represents an individual layer of the hollow cuboid printed structure 302.
There is provided the 3D-printable construction material, which is used to print the hollow cuboid 3D-printed structure 302. The 3D-printable construction material is optimized to ensure enhanced extrusion through the stainless-steel hopper and screw extruder device, while maintaining a stand-off distance of about 16-18 mm and a layer height of about 15 mm. The 3D-printable construction material is prepared to provide consistent flow with precise layer-by-layer deposition at a speed of about 30 mm/s for the periphery to ensure the structural integrity of the hollow cuboid printed structure 302. Furthermore, the 3D-printable construction material includes one part of Portland cement as the binder. The Portland cement is further combined with two parts by weight of fine aggregates, consisting of a blend of the M-sand and the processed excavated soil to reduce the 3D-printable construction material cost while providing the sustainability by substituting some percentage of the sand with locally sourced excavated soil.
Furthermore, the 3D-printable construction material includes the fine aggregates of M-sand, where 25-50% by weight is the excavated soil content containing non-expansive clay. The addition of the excavated soil content in the 3D-printable construction material provides the sustainable and economical substitute for traditional M-sand, reducing the need for natural sand and lowering material costs. Moreover, the non-expansive clay in the excavated soil improves the viscosity and the stability of the cementitious mixture, which is necessary for the preparation of 3D-printable construction material as the non-expansive clay in the excavated soil helps the 3D-printable construction material to retain shape and prevent layer deformation. Furthermore, the 3D-printable construction material includes the first chemical admixture in an amount of 0.10-0.36% by weight of the binder. The first chemical admixture is a superplasticizer used to enhance the fluidity and workability of the 3D printable construction material without increasing the water content in the 3D-printable construction material. In some implementations, the first chemical admixture may include but is not limited to the chemical admixture of polycarboxylate ethers (PCEs), lignosulfonates, naphthalene-based admixtures, sulfonated melamine formaldehyde (SMF), and the like. By precisely adding the first chemical admixture in the cementitious mixture maintains the balance of viscosity and fluidity, enhancing layer adhesion and structural stability of the 3D-printable construction material maintains the balance of viscosity and fluidity, enhancing layer adhesion and structural stability during the 3D-printing. Furthermore, the 3D-printable construction material includes the second chemical admixture in an amount of 0.46-2.75% by weight of the binder. The second chemical admixture is the viscosity modifying agent (VMA) used for enhancing the stability of the 3D-printable construction material and resistance to deformation during and after extrusion. The VMA is configured to optimize the viscosity of the 3D-printable construction material, thereby making the 3D-printable construction material thicker and more cohesive, which is essential for the 3D-printable construction material to hold the shape of 3D-printed structure upon extrusion. In an implementation, the second chemical admixture in the cementitious mixture may include but is not limited to the chemical admixture of hydroxypropyl methylcellulose (HPMC), welan gum, xanthan gum, gellan gum, carboxymethyl cellulose (CMC), and the like.
In an implementation, the 3D printable construction material has a flow spread of 140-150 mm at the first extrusion, ensuring that the 3D printable construction material maintains optimal extrusion quality for the effective 3D printing and can be built up to a height of at least 1 meter. The flow spread of about 140-150 mm ensures that the 3D-printable construction material flows smoothly through the extrusion nozzle without clogging while maintaining enough cohesion to prevent excessive spreading after deposition. The optimized flow spread, typically in the range of 140-150 mm, is necessary for precise layer deposition, thereby preventing inaccuracies and layer misalignment.
The 3D-printable construction material is used to provide the hollow cuboid 3D-printed structure 302 with a footprint of 350 mm × 350 mm. In an implementation, the hollow cuboid printed structure 302 shows a layer-wise build-up methodology executed through a stainless-steel hopper and a screw extruder device. Advantageously, the 3D-printable construction material enhances the overall 3D-printing efficiency by maintaining optimal extrusion conditions with a stand-off distance of 16-18 mm, which corresponds to the designed layer height of 15 mm. The periphery of the hollow cuboid printed structure 302 is precisely printed at 30 mm/s to ensure structural integrity. Furthermore, the individual layer 302A represents the fundamental building block of the hollow cuboid 3D-printed structure 302, which corresponds to the designed layer height of 15 mm. The periphery of the hollow cuboid printed structure 302. The individual layer 302A may include walls constructed using a 20 mm nozzle, which adequately accommodates the maximum particle size of 5 mm in the raw materials. The 3D-printing parameters are optimized for optimum extrusion conditions, ensuring consistent material flow and layer adhesion throughout the build process.
In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 includes water in the water-to-binder ratio of 0.38 to 0.55. The specific ratio is selected to optimize the extrusion quality of the 3D-printable construction material, ensuring that the 3D-printing construction material maintains adequate flowability and structural integrity. By adjusting the water content within such a range, the 3D-printable construction material attains the necessary fluidity for smooth extrusion while also enhancing the stability and cohesion of the 3D-printable construction material once deposited in layers.
In accordance with an embodiment, the binder in the 3D printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 further comprises 30% by weight of supplementary cementitious construction material, which is selected from calcium-alumino-silicate-based industrial by-products such as the Ground Granulated Blast Furnace Slag (GGBS), the Fly Ash, Silica Fume, Rice Husk Ash, and the like. The binder is used to enhance the sustainability and strength of the 3D-printed structure by partially replacing existing cement components. By incorporating the calcium-alumino-silicate-based industrial by-products for preparing the binder, the 3D-printable construction material reduces reliance on existing cement, thereby lowering the environmental impact while still providing the required structural integrity.
In accordance with an embodiment, the excavated soil used in the 3D-printable construction material for printing the hollow cuboid 3D-printed structure 302 further contains the clay content of 42% to 47% and a plasticity index of 16%. Such a specific composition is chosen to impart the desired rheological properties to the 3D-printable construction material, thereby enhancing both plasticity and cohesion of the 3D-printable construction material. By maintaining the range of the clay content and the plasticity, the 3D-printable construction material provides the right balance between flexibility and stability, essential for effective layer formation and material adherence during the 3D printing process. Additionally, the controlled clay content and plasticity within the 3D-printable construction material provides smooth extrusion of the 3D-printable construction material while preventing deformation, thereby ensuring stability and precision in the 3D-printed structure.
In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 provides a shape retention factor in the range of 70% to 92% during the preparation of the 3D-printable construction material. The shape retention characteristic of the 3D-printable construction material ensures that the 3D-printable construction material can retain the intended form after extrusion while enhancing the dimensional accuracy and precision of each printed layer. By optimizing the shape retention factor within the range, the 3D-printable construction material resists deformation upon deposition, thereby allowing for a clean and stable layering process that preserves the structural integrity of the 3D-printed structure.
In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 has a global warming potential (GWP) of 435 to 710 kg CO₂-eq/m³. The reduced GWP in the 3D-printable construction material used for 3D-printing the hollow cuboid 3D-printed structure 302, which contributes to the sustainability by lowering the carbon footprint associated with the construction of the 3D-printed structure from the 3D-printable construction material. Thus, by minimizing the global warming potential (GWP), the 3D-printable construction material reduces the amount of carbon dioxide emissions during production and use of the 3D-printable construction material and the 3D-printed structure.
In accordance with an embodiment, the 3D-printable construction material used in 3D- printing the hollow cuboid 3D-printed structure 302 includes the first chemical admixture (i.e., the viscosity-modifying admixture) and the second chemical admixture (i.e., the superplasticizer). The viscosity-modifying admixture (or the first chemical admixture) improves the ability of the 3D printed material to retain the original shape and cohesion after deposition while the superplasticizer (or the second chemical admixture) reduces the viscosity of the 3D printed material, allowing for smoother flow through the nozzle. Together, the first and second chemical admixtures ensure consistent layer formation, adhesion, and overall printability, contributing to the structural integrity and precision of the final 3D-printed construction element. In accordance with an embodiment, the dosage of the viscosity-modifying chemical admixture (or the first chemical admixture) in the 3D printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 is reduced by 72% due to the use of non-expansive clayey soil. By minimizing the amount of the additional chemical admixtures required, the cost and performance of the 3D-printable construction material is optimized, ensuring that the desired stability is maintained without unnecessary chemical additives.
In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 ensures the height of the 3D-printable construction material that is at least 2.5 times higher than that of the cement-sand mixture. The increased height of the hollow cuboid 3D-printed structure 302 ensures the stacking ability and suitability for large-scale structures without compromising stability. The 3D-printable construction material’s ability to support taller structures enhances the suitability of the 3D-printed structure for large-scale construction applications, enabling the creation of more robust and stable 3D-printed structures while reducing the need for additional support or formwork during the 3D-printing process.
In accordance with an embodiment, the 3D- printable construction material used in 3D-printing the hollow cuboid printed structure 302 exhibits the wet compressive strength of 10 to 28 megapascals (MPa) after being 3D-printed and cured for 28 days. The wet compressive strength of 10 to 28 MPa ensures that the 3D-printable construction material can withstand load-bearing applications and maintain durability over time. In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 provides a reduction in total shrinkage of at least 30% at 56 days compared to the conventional cement-sand mixture. The reduction in shrinkage is achieved by optimizing the 3D-printable construction material's formulation, which minimizes the risks of cracking and deformation with the hollow cuboid 3D-printed structure 302. Thereby, the 3D-printable construction material maintains better dimensional stability, enhancing the longevity and overall structural integrity of the 3D-printed hollow cuboid structure 302.
In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid printed structure 302 exhibits an inter-layer shear bond strength of at least 4 MPa after being 3D-printed and cured for 28 days. The inter-layer shear bond strength is necessary for maintaining cohesion between printed layers, ensuring the overall stability of the structure and resistance to separation under load. The strength at the layer interface is crucial for maintaining the integrity of the 3D-printed structure during both construction and in-service applications. In accordance with an embodiment, the 3D-printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 has a ratio of wet strength to dry strength of at least 0.80 when cured, maintaining sufficient strength in both wet and dry states, providing reliable structural performance throughout different stages of curing and during the application process. By balancing the wet and dry strength, the 3D-printable construction material shows an efficient handling and long-term durability of the hollow cuboid 3D-printed structure 302 in varied environmental conditions.
Advantageously, the 3D printable construction material used in 3D-printing the hollow cuboid 3D-printed structure 302 is configured to enhance the printability, structural stability, and environmental sustainability of the hollow cuboid 3D-printed structure 302, such as by enhancing the overall strength and durability of the hollow cuboid 3D-printed structure 302. The addition of fine aggregates, such as sand or finely crushed stone, combined with about 25% to 50% of the excavated soil content containing non-expansive clay makes the 3D printable construction material both cost-effective and eco-friendly. Moreover, the utilization of non-expansive clay helps prevent shrinkage and cracking, which improves the stability of the hollow cuboid 3D-printed structure 302. Furthermore, the precise combination of the chemical admixtures, with the first admixture serving as the superplasticizer, provides the controlled flow spread of the 3D printable construction material that is about 140-150 mm, thereby optimizing the workability and flow during extrusion of the 3D-printable material.
FIG. 3B depicts another exemplary diagram of the hollow cuboid 3D-printed structure that is prepared using 3D printable construction material, in accordance with an embodiment of the present disclosure. FIG. 3B is described in conjunction with FIG. 1, FIG. 2 and FIG. 3A. With reference to FIG. 3B, there is a shown the diagram 300B that includes the hollow cuboid 3D-printed structure 302 with internal cross-bracings 304.
There is shown the hollow cuboid 3D-printed structure 302, which is structurally enhanced with internal cross-bracings 304. The internal cross-bracings 304 is arranged in an X-pattern configuration throughout the internal structure of the hollow cuboid 3D-printed structure 302. The internal cross-bracings 304 serve as integral reinforcement elements that are printed simultaneously with the main structure (i.e., the internal cross-bracings 304). The X-pattern arrangement of the internal cross-bracings 304 is particularly effective as the X-pattern arrangement helps distribute both vertical and lateral loads throughout the hollow cuboid 3D-printed structure 302. Thus, such pattern arrangement is essential for preventing localized stress concentrations that could potentially lead to any weaknesses in the hollow cuboid 3D-printed 3D structure 302. Additionally, the diagonal orientation of internal cross-bracings 304 provides enhanced resistance against shear forces and torsional movements that might affect the service life of the hollow cuboid printed structure 302. In some implementations, the internal cross-bracing 304 shows an advanced structure approach where the infill is 3D-printed at an increased speed of approximately 60 mm/s while maintaining the peripheral 3D-printing speed at about 30 mm/s. The dual-speed optimization is specifically used for providing the structural design required for maximizing the built height of the hollow cuboid 3D-printed structure 302.
Advantageously, the hollow cuboid 3D-printed structure 302 provided with the internal cross-bracings 304 shows environmental sustainability, structural performance, material efficiency, and an enhanced construction methodology. The 3D-printable-construction material used in printing the hollow cuboid 3D-printed structure 302 achieves a significantly reduced environmental impact with a Global Warming Potential (GWP) of about 435-710 kg CO₂-eq/m³. Moreover, the 3D printing material used for printing the hollow cuboid 3D-printed structure 302 exhibits a wet compressive strength of 10-28 MPa after 28 days of curing, complemented by an inter-layer shear bond strength of at least 4 MPa. The incorporation of clayey soil reduces the need for viscosity-modifying admixtures by 72%, showcasing how natural materials can effectively replace chemical additives. The 3D-printable construction material also maintains a high shape retention factor of 70-92% and achieves a wet-to-dry strength ratio of at least 0.80, indicating excellent stability during both the construction phase and long-term service life of the hollow cuboid 3D-printed structure 302.
FIGs. 4A and 4B depict the graphical representations that illustrate filament width and Shape retention factor (SRF) for different compositions under varying testing conditions, in accordance with an embodiment of the present disclosure. FIGs. 4A and 4B are described in conjunction with FIG.1, FIG.2, FIG. 3A and FIG. 3B. With reference to FIGs. 4A and 4B, there are shown two different graphical representations (i.e., 400A and 400B) representing the relation between the width of extruded layers and the Shape Retention Factor (SRF) for different compositions.
In an exemplary scenario, the graphical representation 400A includes an X-axis 402A that illustrates the different compositions (or the composition) labelled as CS0 (i.e., control sample), CG30, CC25, CC50, CC25G30, and CC50G30 and a Y-axis 404A at the left side represents the average width of extruded layers measured in millimetres (mm), ranging from 0 to 80 mm. Moreover, the right side of the Y-axis 406A represents the Shape Retention Factor (SRF) expressed as a percentage (%) ranging from 0 to 100%. Further, the graphical representation 400A includes a dashed line 408A at approximately 60% SRF is shown as a reference line across the graphical representation 400A. Furthermore, the graphical representation 400A includes various data points that are represented through two distinct symbols, such as squares indicating the loading direction for layer width measurements and circles representing the loading direction for SRF values. The square and the circle symbols are accompanied by error bars, which provide statistical validation of the measurement reliability and demonstrate the consistency of the results across the samples.
In an implementation scenario, the cementitious mixture includes different compositions with different quantities of binders, including the excavated soil, the OPC (i.e., the Ordinary Portland Cement), the GGBS, the fly ash, and the like. The composition CS0 represents the control sample, which refers to the baseline composition. The composition CS0 exhibits an average layer width of approximately 65mm and demonstrates baseline shape retention characteristics. The composition CG30 represents a modified composition where 30% of the cementitious material is replaced with calcium-alumino-silicate-based industrial by-products, such as the GGBS. The incorporation of such industrial by-products influences both the extrusion characteristics and shape retention capabilities of the composition CG30, as evidenced by the altered layer width and SRF values compared to the composition CS0. The compositions CC25 and CC30 indicate formulations containing varying percentages (25% and 30%, respectively) of the clay content within the excavated soil incorporated into the fine aggregate portion, which contributes to the reduction in required chemical admixtures, particularly evident in the 72% reduction in viscosity-modifying admixture usage while maintaining desired flow characteristics. The composition CC50F30 represents an advanced composition incorporating 50% soil along with 30% fly ash, enhancing the flowability and stability. The composition CC50F30 maintains superior shape retention capabilities while ensuring adequate layer width for practical construction applications.
In another exemplary scenario, the graphical representation 400B includes an X-axis 402B that illustrates the different compositions labelled as CS0 (control sample), CG30, CC25, CC50, CC25F30, and CC50F30 and a Y-axis 404B at the left side represents the average width of the extruded layers measured in millimetres (mm), ranging from 0 to 80 mm. Moreover, the right side of the Y-axis 406B represents the Shape Retention Factor (SRF) expressed as a percentage (%) ranging from 0 to 100%. The graphical representation 400B further includes a dashed line 408B at approximately 60% SRF is shown as a reference line across the graphical representation 400B. Furthermore, the graphical representation 400B includes various data points on the graph that are represented through two distinct symbols, such as squares indicating the loading direction for layer width measurements and circles representing the loading direction for SRF values. The symbols (i.e., the squares and the circles) are accompanied by error bars, which provide statistical validation of the measurement reliability and demonstrate the consistency of the results across the samples.
In an implementation, the composition CS0 represents the control sample, comprising the baseline cementitious mixture with the OPC and fine aggregates (only M-sand) in conventional proportions. The composition CS0 exhibits an average layer width of approximately 65 mm under these specific testing conditions and demonstrates consistent shape retention characteristics. The composition CG30, incorporating 30% calcium-alumino-silicate-based industrial by-products, such as the GGBS as a cement replacement demonstrates modified shape retention properties under specific testing conditions. The compositions CC25 and CC50, containing 25% and 50% of the excavated soil, respectively in the fine aggregate portion, exhibit reduced layer widths compared to the composition CS0. The compositions CC25 and CC50 demonstrate the influence of clay content under specific testing conditions, with both the compositions maintaining the SRF values above the threshold indicated by the dashed line 408B. The composition CC50F30, incorporating 50% of the excavated soil and 30% of the fly ash, displays optimized performance characteristics under the provided testing conditions. The composition CC50F30 achieves balanced shape retention capabilities while maintaining practical layer width dimensions, thereby demonstrating the suitability of the composition CC50F30 for construction applications under varying conditions. The composition CC30F30 shows an adapted performance characteristics, with the layer width and the SRF values reflecting influence of both the clay content and flow-enhancing additives under the specified testing conditions.
Thus, the graphical representations 400A and 400B represent a comparative analysis between normal testing conditions shown in the graphical representation 400A and specific testing conditions shown in the graphical representation 400B, revealing the consistency and reliability of the different compositions labelled as CS0, CG30, CC25, CC50, CC25G30, and CC50G30.
FIG. 5 depicts the graphical representation that illustrates the rheological properties of the different compositions through apparent viscosity, in accordance with an embodiment of the present disclosure. FIG. 5 is described in conjunction with FIG.1, FIG.2, FIG. 3A, FIG. 3B, FIG. 4A and FIG. 4B. With reference to FIG 5, there is shown the graphical representations 500 representing the rheological properties of the different compositions through apparent viscosity.
In an exemplary scenario, the graphical representation 500 includes an X-axis 502 that represents the shear rate (s⁻¹) of the four compositions (i.e., CC25, CC50, CC25G30 and CC50G30) ranging from 10 to 50 s⁻¹ and a Y-axis 504 that represents the apparent viscosity (Pa-s) of the four compositions ranging from 0 to 100 Pa-s. Moreover, each composition from the four compositions (i.e., the CC25, the CC50, the CC25G30 and the CC50G30) represents the shear-thinning behaviour, with viscosity decreasing as the shear rate increases. Furthermore, the graphical representation 500 includes four curves with different symbols as a marker to represent different compositions. The curve associated with the triangle symbol represents the composition CC25, having excavated soil content of about 25%. The curve associated with the cross symbol represents the composition CC50, having an excavated soil content of about 50%. Moreover, the curve associated with the square symbol represents the composition CC25G30, which has an excavated soil content of 25% and a GGBS content of 30%. The curve associated with the star symbol represents the composition CC50G30, which has an excavated soil content of 50% and the GGBS content of 30%.
In an implementation, the composition CC25 exhibits a relatively lower viscosity across the range of shear rates compared to the other compositions and also has a lower resistance to flow as compared to the other compositions. In another implementation, the composition CC50 shows an increase in the content of the excavated soil from 25% to 50%, thereby increasing the apparent viscosity of the composition CC50. In yet another implementation, the addition of ground granulated blast furnace slag (GGBS) to the 25% soil in the composition CC25G30 has increased the apparent viscosity of the composition CC25G30 compared to the content CC25. In yet another implementation, the composition CC50G30 exhibits an even higher apparent viscosity across the shear rate range. The addition of the excavated soil content as well as the GGBS in the composition CC50G30 indicates that the combined addition of the 50% excavated soil content and 30% GGBS results in the composition CC50G30 with significantly increased viscosity. Thus, the graphical representation 500 shows the comprehensive comparison of the rheological properties of the different compositions. Furthermore, the composition CC50G30 curve depicted by the symbol star represents the composition with the excavated soil (50%) and the GGBS (30%) shows the highest apparent viscosity.
FIG. 6 depicts the graphical representation that illustrates the mechanical properties of the different compositions through dynamic yield stress, in accordance with an embodiment of the present disclosure. FIG 6 is described in conjunction with FIG.1, FIG.2, FIG. 3A, FIG. 3B, FIG. 4A, FIG. 4B and FIG. 5. With reference to FIG 6, there is shown the graphical representation 600 representing the mechanical properties of the different compositions through the dynamic yield stress.
In an exemplary scenario, the graphical representation 600 includes an X-axis 602 that represents the various compositions (i.e., CS0, CG30, CC25, CC50, CC25G30, and CC50G30) and a Y-axis 604 that represents the dynamic yield stress of the various composition measured in Pascals (Pa) ranging from 0 to 1600 Pa. Moreover, the graphical representation 600 includes bars with different patterns to represent the various time points measured after the first extrusion of the compositions. The first composition, CS0 represents the control sample without any additives, making it the baseline for comparison with other modified compositions. Moreover, the control sample (i.e., the composition CS0) represents the lowest mechanical properties as compared with other compositions. The cementitious mixture CS0 shows the dynamic yield stress ranging from approximately 400 to 650 Pa over time. The second composition CG30, contains 30% of the GGBS shows the improved mechanical properties as compared to the composition CS0, with initial values of mechanical properties starting at 0 minutes around 500 units, increasing to 600 Pa at the 17-minute interval of time. Moreover, the composition CG30 incorporates 30% of the GGBS without any excavated soil, thereby exhibiting more significant mechanical strength development compared to the control sample. The third composition, CC25, which contains 25% of excavated soil content without the GGBS, represents a significant enhancement in mechanical properties as compared to both the composition CS0 and the GGBS-only composition CG30. Moreover, the composition CC25 exhibits an initial dynamic yield stress of approximately 920 Pa at 0 minutes from the first extrusion, which increases to about 1050 Pa after 17 minutes. The hybrid compositions (i.e., CC25G30 and CC50G30) shows an improved rheological properties as compared to other compositions. The composition CC25G30, containing 25% of the excavated soil and 30% of the GGBS, represents mechanical properties, exhibits an initial dynamic yield stress of 1300 Pa consistently throughout the measurement period. Thus, the graphical representation 600 illustrates a systematic comparison of the mechanical properties across various compositions measured from the first extrusion up to 51 minutes, representing clear hierarchical performance patterns and additive effects. Moreover, the graphical representation 600 shows the significant role of the excavated soil in enhancing the mechanical properties of the composition.
FIGs. 7A and 7B depict the Scanning Electron Microscopy (SEM) images of Ordinary Portland Cement (OPC) and Ground Granulated Blast-furnace Slag (GGBS), in accordance with an embodiment of the present disclosure. FIGs. 7A and 7B are described in conjunction with FIG.1, FIG.2, FIG. 3A, FIG. 3B, FIG. 4A, FIG. 4B, FIG. 5 and FIG. 6. With reference to FIGs. 7A and 7B, there are shown two diagrams (i.e.,700A and 700B). The diagram 700A shows the SEM images of the OPC, and the diagram 700B represents the SEM images of GGBS.
In an exemplary scenario, diagram 700A shows the SEM images (or micrographs) of the OPC particles used in the preparation of 3D-printable construction material. The SEM images of the OPC particles are taken at an electron current voltage of V 20.00 kV. The SEM images are taken from a working distance (WD) of 10.7 mm. The SEM image represents OPC particles exhibiting predominantly angular and irregular morphologies in the OPC with relatively uniform size distribution. In another exemplary scenario, diagram 700B shows the SEM images of the GGBS particles used in the preparation of the 3D printable construction material. The SEM image distinctly represents GGBS particles characterized by sharp-edged, angular, and elongated morphologies. Therefore, the SEM images of the OPC and the GGBS particle morphologies observed in the shown images from diagrams 700A and 700B interpret the higher shear stress exhibited by the GGBS-based composition. The OPC particles exhibit predominantly irregular morphologies. Moreover, the angular and elongated nature of the GGBS particles provides mechanical interlocking between particles, which tends to restrict the 3D-printable construction material’s flow and spread after extrusion.
FIGs. 8A and 8B depict the graphical representations that illustrate the plastic viscosity of two different set of compositions, in accordance with an embodiment of the present disclosure. FIGs. 8A and 8B are described in conjunction with FIGs. 1 to 7B. With reference to FIGs. 8A and 8B, there is shown a graphical representation 800A that illustrates the plastic viscosity of the first set of compositions and another graphical representation 800B that illustrates the plastic viscosity of the second second set of composition.
In an exemplary scenario, the graphical representation 800A includes an X-axis 802A that represents the first set of compositions (i.e., GGBS CS0, CG30, CC25, CC50, CC25G30, and CC50G30) and a Y-axis 804A represents the plastic viscosity measured in Pascal-seconds (Pa-s) ranging from 0 to 14 Pa-s. Moreover, the dashed line 806A in the graphical representation 800A represents a reference threshold value of plastic viscosity of approximately 7 Pa-s, which provides a benchmark to compare the flow retention of various compositions.
In an implementation, the graphical representation 800A depicts the plastic viscosity measurements of various compositions, including OPC and the excavated soil-based composition (i.e., CC25, CC50), the conventional OPC-sand-based composition (i.e., CS0), and the OPC-GGBS-sand based composition (i.e., CG30), measured at different time intervals ( i.e., 0, 17, 34, and 51 minutes from the first extrusion during the 3D-printing window). Furthermore, the graphical representation 800A represents that the compositions CC25 and CC50 that exhibit lower plastic viscosity compared to other compositions, such as the composition CS0 and the composition CG30 across the different time durations, where the composition CG30 represents the highest initial plastic viscosity of approximately 12 Pa-s. The compositions containing excavated soil with blended binders, such as CC25G30 and CC50G30, also represents lower plastic viscosity values, confirming easier flow through the nozzle and print head. Further, the lower plastic viscosity values of the compositions containing the excavated soil with blended binders confirm the reduced resistance against flow during 3D-printing and maintaining adequate shape stability of the 3D-printable construction material. In another implimentation, the graphical representation 800B includes an X-axis 802B that represents the second set of compositions (i.e., CC0, CF30, CC25, CC50, CC25F30, and CC50F30) and a Y-axis 804B that represents the plastic viscosity measured in Pascal-seconds (Pa-s) ranging from 0 to 14 Pa-s. Moreover, the dashed line 806B in the graphical representation 800B represents a reference threshold value of plastic viscosity at approximately 7 Pa-s, which provides a benchmark to compare the flow retention of various compositions.
In an implementation, the graphical representation 800B represents that the composition CF30 exhibits the highest initial plastic viscosity of approximately 12.5 Pa-s, which gradually decreases over time to about 8 Pa-s after 51 minutes, while the compositions containing excavated soil (i.e., CC25, and CC50) shows consistently lower plastic viscosity values. Thus, the graphical representation 800B confirms that the compositions CC25, CC50, and the compositions CC25F30 and CC50F30 shows a lower and stable plastic viscosity values over time, confirming an optimal flow characteristics for 3D printing applications.
FIGs. 9A and 9B depict the graphical representations that illustrate the flow retention characteristics of different compositions over the 3D-printing duration, in accordance with an embodiment of the present disclosure. FIGs. 9A and 9B are described in conjunction with FIGs. 1 to 8B. With the reference to FIG. 9A, there is shown a graphical representation 900A that illustrates the flow retention percentage over time for different compositions during the 3D printing and another graphical representation 900B represents the flow retention percentage of some other compositions over a 50-minute 3D-printing duration including the compositions containing fly ash instead of GGBS.
In an exemplary scenario, the graphical representation 900A includes an X-axis 902A that represents the duration of the 3D printing of various compositions in 0 to 50 minutes and a Y-axis 904A that represents the flow retention percentage (from 70 to 100%). Moreover, the graphical representation 900A includes various curves of the compositions (i.e., CS0, CG30, CC25, CC50, CC25G30, and CC50G3), which start at 100% flow retention at 0 minutes, but the curves diverge significantly over time. In an implementation, the composition CS0 represents a declining curve with the flow retention percentage dropping to approximately 75% by 50 minutes, confirming reduced flow sustainability of the composition CS0. In another implementation, the compositions containing the excavated soil content (i.e., CC25 and CC50) maintain more than 90% flow retention throughout the 3D-printing duration, as the excavated soil significantly enhances the flow stability of the composition. Moreover, the hybrid compositions, including excavated soil and GGBS (i.e., CC25G30 and CC50G30) and GGBS-based composition (i.e., CG30) exhibit an intermediate curve, with flow retention values between 80-88% after 50 minutes. Thus, the curves of hybrid compositions exhibit steeper declines in the first 20 minutes followed by more gradual decreases, indicating that initial flow loss is more significant across all compositions.
In another exemplary scenario, the graphical representation 900B includes an X-axis 902B that represents the comparative flow retention performance of the compositions containing fly ash and excavated soil over a 50-minute 3D-printing duration, and a Y-axis 904B representing the flow retention percentage ranging from 70-100%. The graphical representation 900B further includes various curves that represent different compositions, including the composition CS0, which exhibits a sharp decline to 80% flow retention, while the curve for the composition CC50 represents maintains a flow retention flow of about 93% throughout the 3D printing duration. The intermediate curves for the composition CF30, which contains 30% fly ash, CC25 contains 25% excavated soil content, and the hybrid compositions (i.e., CC25F30 and CC50F30) shows better flow retention than but at varying levels between 87-91% at 50 minutes. Thus, the curves for all the compositions initially represent a steeper decline in the first 20 minutes, followed by a more gradual decline, with the hybrid compositions representing a balanced performance that indicates the interaction between excavated soil and fly ash in maintaining retention flow properties during the extended 3D-printing process.
FIG. 10 depicts the graphical representation that illustrates the change in viscosity of three different compositions across different intervals of time, in accordance with an embodiment of the present disclosure. FIG 10 is described in conjunction with FIG.1 to 9B. With reference to FIG 10, there is shown the graphical representation 1000 measuring viscosity (in Pa-s) over time for three different compositions (i.e., CF30, CC25F30, CC50F30).
In an exemplary scenario, the graphical representation 1000 includes an x-axis 1002 that represents the time in seconds (s) from 0 to 240 seconds across the three intervals of the 3D printing process and a Y-axis 1004 that represents viscosity measured in Pa-s on a logarithmic scale, ranging from 1 to 100,000 Pa-s. The graphical representation 1000 further includes the viscosity measured in Pascal-seconds (Pa-s) over a 240 second timeline for three different compositions, including CF30, CC25F30 and CC50F30. The graphical representation 1000 further illustrates the process for measuring the viscosity that is divided into three distinct intervals, such as at a first instant 1006 (i.e., the instant when the different compositions are inside the hopper), a second instant 1008 (i.e., the instant when the different compositions are in the extrusion phase), and a third instant 1010 (i.e., the instant when the different compositions are deposited on the printing bed).
In an implementation, the first composition CF30 contains 30% fly ash, represents the lowest initial viscosity, around 1,000 Pa-s, indicating better flowability but potentially less structural stability. The composition CF30 depicts a sharp drop in viscosity during the phase of extrusion, that is the second instant 1008 to about 10 Pa-s like other compositions. However, the recovery of the composition CF30, which was initially held in the hopper, that is at the first instant 1006, shows a much more gradual increase in viscosity after deposition and fails to reach the 90% recovery target. In another implementation, the composition CC25F30 contains 25% excavated soil content and 30% fly ash, representing an intermediate initial viscosity of approximately 10,000 Pa-s. Further, the composition CC25F30 ensures flowability and stability. The composition CC25F30 represents a drop during the phase of extrusion, that is the second instant 1008, but the recovery phase illustrates better characteristics than the composition CF30. The composition CC25F30 recovers more quickly and maintains a more stable viscosity, approaching closer to the 90% recovery during deposition on the print bed, that is the third instant 1010. In yet another implementation, the composition CC50F30, which contains 50% excavated soil content and 30% fly ash, exhibits the highest initial viscosity at around 20,000 Pa-s, depicting strong structural stability. The composition CC50F30 shows the quick recovery characteristics, including returning to near the initial viscosity and maintaining the highest stability throughout the 3D-printing process, ensuring shape retention and structural integrity in the 3D-printable construction material. Thus, the graphical representation 1000 represents the comparative analysis of the rheological properties of three distinct compositions (i.e., CF30, CC25F30, CC50F30) during the 3D-printing process over 240 seconds, where each composition contains varying ratios of the 3D-printable construction materials. Moreover, the graphical representation 1000 represents that the composition CC50F30 with the highest excavated soil content, depicting superior viscosity of about 20,000 Pa-s, followed by the composition CC25F30 represents moderate viscosity of about 10,000 Pa-s, while the composition CF30 exhibits lowest viscosity of about 1,000 Pa-s.
FIG. 11 depicts the graphical representation that illustrates the recovery in viscosity for various compositions, in accordance with an embodiment of the present disclosure. FIG 11 is described in conjunction with FIGs. 1 to 10. With reference to FIG 11, there is shown the graphical representation 1100 represents the recovery in viscosity (particularly in %) for various compositions.
In an exemplary scenario, the graphical representation 1100 includes an X-axis 1102 that represents different compositions, including the composition CC0 (i.e., the control sample), the composition CF30 that contains 30% fly ash, the composition CC25 that contains 25% excavated soil content, the composition CC50 that contains 50% excavated soil content, the composition CC25F30 that contains 25% excavated soil content and 30% fly ash, and the composition CC50F30 that contains 50% excavated soil content and 30% fly ash and a Y-axis 1104 represents the percentage (%) of recovery in viscosity ranging from 0 to 120%. Moreover, in the graphical representation, the dashed line 1106 represents the minimum threshold for acceptable viscosity recovery in the composition.
The first composition, CC0, represents the control sample without excavated soil content or fly ash content in the graphical representation 1100. The composition CC0 represents the recovery value of 70% in viscosity, the baseline performance that exactly meets the minimum threshold requirement and represents that the composition CC0 is functional but lacks enhanced recovery properties. Further, the composition CF30 that contains 30% fly ash represents weak recovery in viscosity with only 58% recovery, indicating that fly ash alone, providing other mechanical benefits, is insufficient for maintaining adequate viscosity recovery and yield stress development. Furthermore, the composition CC25 that contains 25% excavated soil illustrates viscosity recovery at approximately 100%, marking a substantial improvement over the control and fly ash-only compositions and ensures that even moderate excavated soil content effectively improves the 3D-printable construction material’s stability and rheological properties that are necessary for 3D-printing. Moreover, the composition CC50 contains 50% excavated soil and represents the highest recovery at 110% and ensures that increased content of the excavated soil provides optimized viscosity recovery and yield stress development that further provide structural stability and shape retention properties in the 3D-printable construction material. Moreover, the composition CC25F30 contains 25% excavated soil with 30% fly ash and maintains a viscosity recovery of around 90%. The combination of the excavated soil content and fly ash in the composition CC25F30 ensures improved viscosity recovery properties. Furthermore, the composition CC50F30 that contains 50% excavated soil content with 30% fly ash represents similar viscosity recovery to the composition CC25F30 that is approximately 90%, ensuring that doubling excavated soil content in combination with the compositions does not proportionally improve recovery properties and suggests an optimal excavated soil content threshold exists for combinations in the composition, beyond which additional excavated soil content may not provide significant rheological benefits.
FIG. 12 depicts a pictorial representation of the 3D printed structures formed by 3D printing of the 3D printing construction material, in accordance with the present disclosure. FIG 12 is described in conjunction with FIGs. 1 to 11. With the reference to FIG. 12, there is shown the pictorial representation 1200 that includes the 3D-printed structures (i.e., a fist 3D-printed structure 1202, a second 3D-printed structure 1204, a third 3D-printed structure 1206, a fourth 3D-printed structure 1208, a fifth 3D-printed structure 1210, a sixth 3D-printed structure 1212, a seventh 3D-printed structure 1214, and an eighth 3D-printed structure 1216) of the various compositions.
There is provided the first 3D-printed structure 1202, made from the composition CS0 (i.e., the control sample).The first 3D-printed structure 1202 reached a height of 540 mm through layer-by-layer deposition, with each layer having a height of 15 mm, resulting in 36 layers printed over 45 minutes. However, many cracks and discontinuities were seen in the first 3D-printed structure 1202, which can be attributed to several rheological limitations, such as lower static yield stress compared to soil-containing mixes, poor thixotropic properties (71% viscosity recovery), higher plastic viscosity making extrusion more difficult, and lower flow retention (77%) compared to soil-containing mixes. Furthermore, the second 3D -printed structure 1204, made from the composition CF30 (i.e., the fly ash (FA) as 30% replacement of OPC by mass and sand as fine aggregate). The second 3D -printed structure 1204 reached a height of 480 mm through layer-by-layer deposition, with each layer having a height of 15 mm, resulting in 32 layers printed over 40 minutes. Moreover, the third 3D-printed structures 1206, made from the composition CC25 (i.e., the printable mortar containing OPC and excavated soil as 25% replacement of sand). The third 3D-printed structure 1206 reached a height of 1000 mm through layer-by-layer deposition, with each layer having a height of 15 mm, resulting in 67 layers printed over 83.75 minutes. Furthermore, the fourth 3D-printed structure 1208 made from the composition CC50 (i.e., printable mortar containing OPC and excavated soil as 50% replacement of sand). The fourth 3D-printed structure 1208 reached a height of 1200 mm, through layer-by-layer deposition, with each layer having a height of 15 mm, resulting in 80 layers printed over 100 minutes. Moreover, the fifth 3D-printed structure 1210 made from the composition CC25F30 (i.e., printable mortar containing FA as 30% replacement of OPC and excavated soil as 25% replacement of sand). The fifth 3D-printed structure 1210 reached a height of 1200 mm, through the layer-by-layer deposition , with each layer having a height of 15 mm, resulting in 80 layers printed over 100 minutes. Furthermore, the sixth 3D-printed structure 1212 of the composition CC50F30 (i.e., printable mortar containing FA as 30% replacement of OPC and excavated soil as 25% replacement of sand). The sixth 3D-printed structure 1212 reached a height of 1200 mm, through the layer-by-layer deposition , with each layer having a height of 15 mm, resulting in 80 layers printed over 100 minutes. Moreover, the seventh 3D-printed structure 1214 of the composition CC25G30 (i.e., printable mortar containing GGBS as 30% replacement of OPC and excavated soil as 25% replacement of sand). The seventh 3D- printed structure 1214 reached a height of 1200 mm through the layer-by layer deposition, with each layer having a height of 15 mm resulting in 80 layers. However, smooth layer quality were seen in the seventh 3D-printed structure 1214, which can be attributed to several rheological properties, such as higher static yield stress compared to other compositions, excellent thixotropic properties (90-100% viscosity recovery), lower plastic viscosity reducing resistance during extrusion, and enhanced flow retention (92%) compared to other compositions. Furthermore, the eighth 3D-printed structure 1216 of the composition CC50G30 (printable mortar containing GGBS as 30% replacement of OPC and excavated soil as 50% replacement of sand). The eighth 3D-printed structure 1216 reached a height of 1200 mm, through the layer-by-layer deposition, with each layer having a height of 15 mm resulting in 80 layers. The eighth 3D-printed structure 1216 shows the smooth layer quality, which can be attributed to several rheological properties, such as the higher static yield stress, excellent thixotropic properties, ( 90–100% viscosity recovery), lower plastic viscosity ensured easier extrusion, and the high flow retention (92%) compared to other compositions.
Thus, the compositions CC25G30 and CC50G30 shows significantly better rheological properties as compared to other compositions. The compositions CC25G30 and CC50G30 shows the unique properties of the combination of the excavated soil content and the GGBS, including the enhanced thixotropic properties and higher static yield stress and the like. Additionally, the compositions CC25G30 and CC50G30 ensures stability and buildability ot the 3D-printed structures.
FIG. 13 depicts a schematic representation illustrating the extraction of the composition from 3D printed strips through a wet cutting method, in accordance with the present disclosure. FIG 13 is described in conjunction with FIGs. 1 to 12. With reference to FIG 13, there is shown the schematic representation 1300, which includes the X-Y-Z coordinate system represents the fundamental spatial orientation of the 3D printable construction material.
There is shown the schematic representation 1300 includes a top portion 1308 represents a 1200 mm long printed strip with a 60x60 mm cross-section, indicating the 3D printing direction and cutting plane 1310. The schematic representation 1300 further includes a cube 1312 that is made from the 3D printed strip that will be tested for mechanical properties. The bottom portion 1314 represents three different loading directions, L1, L2, and L3, corresponding to the X, Y, and Z coordinate systems, respectively. Moreover, the schematic representation 1300 represents the visualization of layer stacking and nozzle movement direction 1316. The comprehensive methodology for extracting and testing the 3D-printable construction material. In the schematic representation 1300, the coordinate system provides spatial orientation parameters, where X-axis 1302 represents the printing direction length, Y-axis 1304 represents the width dimension corresponding to nozzle movement, and Z-axis 1306 represents the build-up height through layer stacking. The cutting plane 1310 illustrates the wet cutting method used for precise composition extraction, which is essential for maintaining structural integrity and ensuring accurate test results.
In an implementation, the cube 1312 is systematically tested under three distinct loading directions, as shown in the bottom portion 1314 of the schematic representation loading direction including L1 corresponds to the X-axis, testing the properties of the 3-D printable cementitious mixture along with the different printing direction, where L2 aligns with the Y-axis, evaluating properties perpendicular to the printing direction and parallel to nozzle movement and L3 corresponds to the Z-axis, assessing properties across the layer interfaces. The visualization of layer stacking and nozzle movement direction 1316 provides context for understanding the composition and anisotropic properties resulting from the 3D printing process. The comprehensive testing and thorough characterization of mechanical properties across all critical orientations are essential for understanding how the 3D printing process affects the composition’s performance and structural integrity in different loading scenarios.
FIGs. 14A, 14B, 14C and 14D depict the graphical representations that illustrate the mechanical properties of various compositions under three loading directions in accordance with an embodiment of the present disclosure. FIGs. 14A, 14B, 14Cand 14D are described in conjunction with FIGs. 1 to 13. With reference to FIGs. 14A and 14C, there are shown the graphical representations 1400A and 1400C represent the 28-day wet compressive strength (MPa) for the six different compositions (i.e., CS0, CG30, CC25, CC50, CC25G30, and CC50G30), including the GGBS and the fly ash tested in three loading directions. Further, the graphical representations 1400B and 1400D represent the 28-day wet and dry strength ratio for the similar compositions and loading directions, with a reference dashed line at a wet and dry strength ratio of 1.0.
In an exemplary scenario, the graphical representation 1400A includes an X-axis 1402A that represents six compositions (i.e., CS0, CG30, CC25, CC50, CC25G30, and CC50G30) and a Y-axis 1404A represents the compressive strength in MPa ranging from 0 to 50. The graphical representation 1400A represents 28-day wet compressive strength measurements across the six different compositions. Each composition is tested in three loading directions represented by different patterns of bars. The composition CS0 exhibits the highest strength of about 30-32 MPa with directional variation, while excavated soil containing compositions (i.e., CC25 and CC50) represents more uniform but lower strengths. The hybrid compositions (i.e., CC25G30, and CC50G30) represents moderate strength with directional dependence, particularly in the L1 direction. Each measurement includes bars indicating experimental uncertainty, providing insight into the reliability and variability of the test results. The comprehensive strength analysis confirms how different compositions and loading directions influence the mechanical properties of 3D printable construction material, with clear trends representing the impact of the excavated soil content and the GGBS addition on strength characteristics.
In another exemplary scenario, the graphical representation 1400B includes an X-axis 1402B represents six compositions (i.e., CS0, CG30, CC25, CC50, CC25G30, CC50G30), each tested in three loading directions and a Y-axis represents 1404B represents 28-day wet and dry strength ratio from 0 to 1.40, with a reference line at 1.0 indicating equal wet and dry strength performance. Furthermore, the graphical representation 1400B represents the three loading directions by different bars with a critical reference threshold shown by a dashed line 1406B at 1.0. The composition CS0 represents near-uniform ratios close to 1.0 across all directions, while the composition CG30 represents enhanced performance with ratios exceeding 1.0 in L2 and L3 directions. The excavated soil content containing compositions, including CC25 and CC50 exhibits varied performance with generally lower ratios in the L1 direction but improved performance in the L2 direction. Moreover, the hybrid compositions, including CC25G30 and CC50G30 represent strength retention patterns, with the composition CC25G30 representing particularly strong performance in the L2 direction, exceeding the 1.0 threshold. The ratio analysis provides an analysis of the composition’s durability and strength retention under wet conditions, with values above 1.0 indicating superior wet condition performance compared to dry conditions.
Thus, the graphical representations 1400A and 1400B collectively represent the comparative analysis of concrete strength properties under different conditions and composition. The graphical representation 1400A represents the absolute 28-day wet compressive strength values in MPa, with the composition CS0 exhibiting the highest strength values around 30-32 MPa. In contrast, subsequent modifications generally represent decreased strength values. The variations in strength along different loading directions, L1, L2, and L3, indicate anisotropic properties in compositions. The graphical representation 1400B represents the wet-to-dry strength ratios for the same composition, confirming how moisture affects the composition performance. The reference line 1406B at 1.0 serves as a benchmark where wet and dry strengths are equal, while the composition CS0 represents consistent ratios near 1.0, modified composition like CG30 represents more variable properties with ratios ranging from 0.7 to 1.3.
In yet another exemplary scenario, the graphical representation 1400C includes an X-axis 1402C that represents the six compositions (i.e., CS0, CF30, CC25, CC50, CC25F30, CC50F30) tested in the three loading directions, and the Y-axis that represents the 28-day wet compressive strength in MPa, ranging from 0 to 50 MPa. Furthermore, the graphical representation 1400C represents the three loading directions L1, L2, and L3, using three distinct bar patterns for each composition. In an implementation, the composition CS0 exhibits the highest 28-day wet compressive strength, ranging between 30 and 35 MPa, across all three loading directions. The composition CF30 represents slightly reduced strength values compared to the composition CS0 across all three directions, with the L1 direction showing the highest strength. The compositions containing excavated soil (i.e., CC25 and CC50) represent slightly lower compressive strengths compared to the compositions CS0 and CF30 but maintain relatively uniform performance across all the loading directions. Moreover, the hybrid compositions, such as CC25F30 and CC50F30 represent a further reduction in compressive strength but exhibit enhanced anisotropy, with L1 directions consistently higher than L2 and L3 directions. Thus, the comprehensive strength analysis shows how different compositions and loading directions influence the mechanical properties of 3D printable construction material, with clear trends representing the impact of excavated soil content and fly ash addition on strength characteristics.
In yet another exemplary scenario, the graphical representation 1400D includes an X-axis 1402D representing six compositions (i.e., CS0, CF30, CC25, CC50, CC25F30, CC50F30), each tested in three loading directions, and the Y-axis 1404D representing the 28-day wet and dry strength ratio ranging from 0 to 1.2, with a reference line at 1.0 indicating equal wet and dry strength performance. Furthermore, the graphical representation 1400D represents the three loading directions L1, L2, and L3 by distinct bar patterns, with a critical reference threshold shown by the dashed line 1406D at 1.0. The composition CS0 represents near-uniform ratios close to 1.0 across all directions. In contrast, the composition CF30 shows a reduced performance in all directions, with a value of the wet and dry strength ratio below 1.0 reference. The excavated soil-containing compositions, including CC25 and CC50, exhibit varied performance, with lower wet and dry strength ratios in the L1 direction but moderate to strong retention in the L2 and L3 directions. Furthermore, the hybrid compositions, such as CC25F30 and CC50F30, which include fly ash represent enhanced performance, with wet and dry strength ratios exceeding 1.0 in L2 and consistent performance in L3. Thus, the analysis wet and dry strength ratio provides the composition’s durability and strength retention under wet conditions.
FIGs. 15A and 15B depict the graphical representations illustrating the total shrinkage properties of the compositions over time, in accordance with an embodiment of the present disclosure. FIGs. 15A and 15B are described in conjunction with FIGs. 1 to 14B. With reference to FIGs. 15A and 15B, there is shown a graphical representation 1500A that represents the total shrinkage properties of six different compositions (i.e., CS0, CF30, CC25, CC25F30, CC50, CC50F30) over 56 days and another graphical representation 1500B that represents the total shrinkage properties of six different compositions CS0, CG30, CC25, CC50, CC25G30, CC50G30 over 56 days.
In an exemplary scenario, the graphical representation 1500A includes an X-axis 1502A that represents the age of the composition in days and a Y-axis 1504A that represents the total shrinkage in microstrains (με), ranging from +100 to -1500, where negative values indicate contraction or shrinkage of the compositions. The control sample or the composition CS0 is the baseline for comparison, representing moderate shrinkage characteristics that stabilize around -700 με after 28 days. Similarly, the fly ash containing composition CF30 that contains 30% fly ash as cement replacement, exhibits comparable shrinkage, thereby improving the workability and sustainability aspects of the composition CF30. In an implementation, the compositions, such as CC25 and CC50, containing excavated soil represent significantly higher shrinkage values, reaching between -1200 to -1400 με, demonstrating that an increase in excavated soil content leads to greater shrinkage, which could be attributed to higher moisture content and dimensional instability of some unstabilized clay in the soil-based compositions. Additionally, thecomposition CC50 with 50% increased excavated soil content, the highest shrinkage among all compositions is recorded. Moreover, the hybbrid compositions, such as CC25F30 and CC50F30, incorporating both excavated soil and fly ash, the shrinkage is similar to the composition CS0, confirming that fly ash effectively mitigates the shrinkage tendency of soil-based mixes. However, the composition CC50F30 still exhibits high shrinkage, confirming that fly ash's shrinkage-reducing effect has limitations when excavated soil content is substantially increased. Additionally, the other compositions represent rapid shrinkage within the first 14 days, followed by a gradual stabilization period. The initial rapid shrinkage can be attributed to early-age chemical reactions and moisture loss. After 28 days, most compositions represent minimal additional shrinkage, confirming better volumetric stability than at the early stage.
In another exemplary scenario, the graphical representation 1500B includes an X-axis 1502B that represents the age of the compositions in 56 days, spanning from 0 to 56 days. The Y-axis that represents 1504B represents total shrinkage in macrostrains (με). The control sample or the composition CS0 represents the baseline performance, showing moderate shrinkage that stabilizes around -700 με after 28 days. The GGBS-cement compositions containing 30% ground granulated blast furnace slag (i.e., CG30) as cement replacement show similar shrinkage behaviour as that of the control sample (i.e., CS0), indicating that GGBS effectively maintains shrinkage control while potentially providing improved durability and environmental benefits. The composition, CC50, with 50% excavated soil content exhibits the highest shrinkage among all compositions. The correlation between an increase in clay content due to higher soil dosage and increased shrinkage potential is evident. The increased shrinkage potential is likely caused by an increase in water demand and the volumetric instability of clay. Moreover, the hybrid compositions, such as CC25G30 and CC50G30, which incorporate both the excavated soil content and the GGBS, represent distinct shrinkage patterns. The hybrid compositions, such as CC25G30 and CC50G30, still exhibit relatively high shrinkage values, which indicates that GGBS's shrinkage-reducing capabilities may be limited when dealing with significantly increased excavated soil content.
From the experimental data, the observation includes the influence of fly ash and ground granulated blast furnace slag (GGBS) on the shrinkage behaviour of the respective compositions over 56 days. However, when the compositions, such as CC25 and CC50 exhibits significantly higher shrinkage values ranging from -1100 to -1400 με, with the composition CC50 consistently showing high shrinkage. Moreover, the compositions comprising blended binders such as cement and fly ash or cement and GGBS (i.e., CC25F30, CC50F30, CC25G30 and CC50G30) register lower shrinkage than the composition CC50, indicating the effectiveness of GGBS and FA in mitigating the rate of shrinkage. Thus, the compositions across both the graphical representation 1500A and 1500B show rapid initial shrinkage within the first 14 days, followed by gradual stabilization, though the final stabilized shrinkage values and rates of stabilization vary based on the specific combination of excavated soil content and type of additive used.
FIGs. 16A and 16B depict the graphical representations that illustrate the inter-layer bond strength of the different compositions tested in two loading directions, L1 and L2, in accordance with an embodiment of the present disclosure. FIGs. 16A and 16B are described in conjunction with FIGs. 1 to 15B. With reference to FIGs. 16A and 16B, there is shown a graphical representation 1600A that represents the inter-layer bond strength in MPa of six different compositions (i.e., CC0, CF30, CC25, CC25F30, CC50, and CC50F30) tested in two loading directions L1 and L2. There is shown another graphical representation, 1600B, that represents the inter-layer bond strength in MPa of three compositions (i.e., CC0, CC50, and CC50G30) tested in two loading directions, L1 and L2.
In an exemplary scenario, the graphical representation 1600A includes an X-axis 1602A that represents different compositions, including two distinct bar patterns for L1 and L2 representing loading directions, and a Y-axis 1604A that represents the bond strength measured in MPa ranging from 0 to 6 MPa. The control sample or the composition CC0 represents the baseline performance, showing a higher strength of 3.80 MPa in the L1 direction compared to 2.30 MPa in L2. The ompositions containing fly ash as a 30% replacement of OPC represent a similar strength of about 2.80 MPa in both loading directions, L1 and L2. The compositions, CC25 and CC50, containing 25% and 50% excavated soil, respectively represent distinct behaviours. The composition, CC25, exhibits improved strength compared to the control cementitious mix, reaching 4.1 MPa in the L1 direction. However, the composition CC50 represents reduced strength in both directions, including L1 and L2, confirming that excessive excavated soil content may not necessarily improve bond strength. Moreover, the comprising cement and fly ash together with excavated soil, represented by CC25F30 and CC50F30, show contrasting behaviours. The composition, CC25F30, represents the highest overall bond strength, approximately 5 MPa in L1 and 4 MPa in L2, which ensures synergy between excavated soil and fly ash addition. However, the compositions, CC50F30, registers the lowest bond strength among all the cementitious mixes, indicating that an increase in the content of excavated soil can adversely affect bond strength even when a supplementary binder, fly ash in this case, is added.
In another exemplary scenario, the graphical representation 1600B includes an X-axis 1602B representing different compositions and a Y-axis 1604B representing the bond strength measured in MPa ranging from 0 to 6 MPa. In the graphical representation, 1600B represents the inter-layer bond strength comparison of three compositions. Further, the graphical representation includes diagonal-lined bars for the L1 direction and gradient-filled bars for the L2 direction. The control csample or the composition CC0, represents the baseline reference, illustrating the highest bond strength among all cementitious mixes in the L1 direction, approximately 3.8 MPa. However, the composition, CC0, shows significantly lower strength in the L2 direction, around 2.3 MPa, indicating a strong directional dependency in bond strength for the control sample without soil or supplementary binders (GGBS or FA). Moreover, the increased excavated soil content in the composition CC50, results in similar bond strength in L1 and L2 directions, approximately 2.5 MPa, suggesting that a higher dosage of excavated soil may reduce the directional dependency of bond strength. Furthermore, the GGBS-incorporated composition, CC50G30, combining 50% excavated soil content with 30% GGBS, represents a slightly higher strength of 3.3 MPa than the composition CC50 in the L1 direction (2.50 MPa) while maintaining similar strength in L2 direction at approximately 2.7 MPa ensures that the GGBS addition in the composition partially mitigates the strength reduction caused by the addition of relatively high amount of excavated soil.
FIG. 17 depicts an exemplary diagram that illustrates a sequence of execution for a process of developing and printing 3D-printable construction material in accordance with an embodiment of the present disclosure. With reference to FIG. 17, there is shown a diagram 1700 depicting the sequence of execution for a process of developing and printing 3D-printable construction material. The diagram 1700 depicts the operations from 1702 to 1706.
At operation 1702, the preparation of 3D printable construction material begins with the composition selection and characterization phase. During the initial stage, four primary compositions are processed, including but not limited to the soil, the GGBS, the fly ash, and the OPC. Furthermore, the operation 1702 includes various sub-operations including sub-operation 1702A, 170B, and 1702C. At sub-operation 1702A, the raw or the excavated soil undergoes initial preparation, where the excavated soil is air-dried at room temperature to remove excess moisture. At sub-operation 1702B, the process includes drying and sieving procedures. Further, the sub-operation 1702C concludes with a thorough determination of clay type and soil content used in the preparation of the composition.
During the material selection for compositions and their characterization, four raw materials are processed, including but not limited to the soil, the GGBS, the fly ash, and the cement. In an example, the basic composition (i.e., CS0 or CC0) includes the OPC (typically 100 grams) and the M-sand (typically 200 grams) prepared at a water-binder ratio of 0.40. Moreover, the basic composition (i.e., CS0 or CC0) includes two chemical admixtures - SP (0.71% by weight of the binder) and VMA (0.20% by weight of the binder). The flowability of the basic 3D-printable mixture composition (i.e., CS0 or CC0) is 188 ± 1.00mm.
In another example, the fly ash modified composition (i.e., CF30) includes the OPC (typically 70 grams), fly ash (typically 30 grams) as 30% replacement of OPC by mass, and the M-sand (typically 200 grams) with the water-binder ratio of 0.40. Moreover, the fly ash-modified composition (i.e., CF30) includes two chemical admixtures the SP (0.71% by weight of the binder) and the VMA (0.20% by weight of the binder). The flowability of the the fly ash modified composition (i.e., CF30) is 188 ± 1.00 mm.
In yet another example, the GGBS modified (i.e., CG30) includes the OPC (typically 70 grams), GGBS (typically 30 grams) as 30% replacement of OPC by mass, and the M- sand (typically 200 grams) with the water-binder ratio of 0.38. Moreover, the GGBS-modified composition (i.e., CG30) includes two chemical admixtures: the SP (0.50% by weight of binder ) and the VMA (0.25% by weight of the binder ). The flowability of the GGBS modified composition (i.e., CG30) is 186 ± 1.00mm.
In still another example, the excavated soil content modified composition (i.e., CC25) includes the OPC (typically 100 grams), the M-sand (typically 150 grams), and the excavated soil content (typically 50 grams) as 25% replacement of the sand with the water-binder ratio of 0.45. Moreover, the excavated soil content modified composition (i.e., CC25) includes two chemical admixtures: the SP (1.35% by weight of the binder) and the VMA( 0.10% by weight of the binder). The flowability of the excavated soil content modified composition (i.e., CC25) is 144 ± 1.50 mm.
In a further example, the enhanced excavated soil content modified composition (i.e., CC50) includes the OPC (typically 100 grams), the M-sand (typically 100 grams), and the excavated soil content (typically 100 grams) as 50% replacement of sand with the water-binder ratio of 0.52. Moreover, the excavated soil content modified composition (i.e., CC50) includes two chemical admixtures: the SP ( 1.75% by weight of the binder ) and the VMA (y 0.10% by weight of the binder). The flowability of the enhanced excavated soil content modified composition (i.e., CC50) is 145 ± 2.00 mm.
In yet a further example, the GGBS-soil modified composition (i.e., CC25G30) includes the OPC (typically 70 grams), the GGBS (typically 30 grams) as 30% replacement of the OPC, the M-sand (typically 150 grams), and the excavated soil content (typically 50 grams) as 25% replacement of sand with the water-binder ratio of 0.43. Moreover, the GGBS-soil modified composition (i.e., CC25G30) includes two chemical admixtures: the SP ( 1.30% by weight of the binder) and the VMA (0.10% by weight of the binder. The flowability of the GGBS-soil modified composition (i.e., CC25G30) is 140 ± 2.00 mm.
In still a further example, the enhanced GGBS-soil modified composition (i.e., CC50G30) includes the OPC (typically 70 grams), the GGBS (typically 30 grams) as 30% replacement of the OPC, the M-sand (typically 100 grams), and the excavated soil content (typically 100 grams) as 50% replacement of the sand with the water-binder ratio of 0.52. Moreover, the enhanced GGBS-soil modified composition (i.e., CC50G30) includes two chemical admixtures: the SP (1.75% by weight of the binder) and the VMA (0.10% by weight of the binder). The flowability of the enhanced GGBS-soil modified composition (i.e., CC50G30) is 140 ± 2.50 mm.
In another example, the fly ash-excavated soil content modified composition (i.e., CC25F30) includes the OPC (typically 70 grams), the fly ash (typically 30 grams) as 30% replacement of OPC, M-sand (typically 150 grams), and excavated soil content (typically 50 grams) as 25% replacement of the sand with the water-binder ratio of 0.45. Moreover, the fly ash-excavated soil content modified composition (i.e., CC25F30) includes two chemical admixtures: the SP (2.00% by weight of the binder) and the VMA (0.10% by weight of the binder). The flowability of the fly ash-excavated soil content modified composition (i.e., CC25F30) is 145 ± 1.00mm.
In yet another example, the enhanced fly ash-excavated soil content modified composition (i.e., CC50F30) includes the cement (typically 70 grams), the fly ash (typically 30 grams) as 30% replacement of OPC, the M-sand (typically 100 grams), and the excavated soil content (typically 100 grams) as 50% replacement of the sand with the water-binder ratio of 0.55. Moreover, the enhanced fly ash-excavated soil content modified composition (i.e., CC50F30) includes two chemical admixtures: the SP (2.75% by weight of the binder) and the VMA (0.10% by weight of the binder). The flowability of the enhanced fly ash-excavated soil content modified composition (i.e., CC50F30) is 150 ± 1.50 mm.
At operation 1704, the process includes optimization of the excavated soil and binder contents under controlled laboratory conditions. The operation 1704 further includes two sub-operations, including 1704A and 1704B. At sub-operation 1704A, the effect of blended binders on reactivity is determined by analyzing various combinations of Ordinary Portland Cement with Ground Granulated Blast Furnace Slag (OPC-GGBS) and Ordinary Portland Cement with Fly Ash (OPC-FA). At sub-operation 1704B, the effect of blended binder on compressive strength is ascertained through systematic testing. Further, at sub-operation 1704B, the standard 50 mm cubes made with the cementitious mixtures are prepared with the composition and cured under controlled conditions.
At operation 1706, the process includes a comprehensive rheological assessment through four interconnected sub-operations essential for 3D printing applications. The operation 1706 further includes two sub-operations including 1706A, 1706B, 1706C and 1706D. The sub-operation 1706A optimizes the static yield stress using a rheometer with parallel plate geometry, measuring across shear rates. At sub-operation 1706B, the process includes providing dynamic yield stress through controlled stress protocol. Furthermore, at sub-operation 1706C, the process includes the evaluation of thixotropic behaviour using a three-interval-thixotropy test. Moreover, at sub-operation 1706D, the process includes examining structural build-up through stress growth measurements at 0, 15, 30, and 60-minute intervals, demonstrating rates of structural build-up.
At operations 1708, the process includes determining the 3D printing process parameters through systematic evaluation and calibration. Operation 1708 further includes the sub-operation 1708A. The operation 1708 begins with the rheologically optimized mixture (from Operation 1706) exhibiting static yield stress of about 1.5 - 2.0 kPa. Further, sub-operation 1708A evaluates printing speed and extrusion rate correlations using a 3D printer equipped with a screw extruder (nozzle diameter: 20 mm).
At operation 1710, the process includes determining optimal composition based on extrusion quality and shape retention characteristics. The operation 1710 further includes a sub-operation 1710A. The operation 1710 utilizes the optimized printing parameters from operation 1708. At sub-operation 1710A the extrusion quality through quantifiable metrics is assessed, including green strength development and shape retention factor measurements using digital image analysis.
At operation 1712, the process includes evaluating the buildability and extrudability characteristics of the optimized composition (from operation 1710). The operation 1712 further includes the sub-operation 1712A. At sub-operation 1712A, the process includes establishing the engineering performance of the 3D printed structures, specifically assessing buildable height capabilities and print quality parameters.
At operation 1714, the process includes comprehensive engineering performance evaluation through two distinct but interconnected sub-operations focusing on mechanical properties and durability characteristics. The operation 1714 further includes sub-operations 1714A, 1714B. At sub-operation 1714A, the process includes systematically determining mechanical strength characteristics in three orthogonal directions using standard cube specimens printed under controlled conditions and tested using a calibrated universal testing machine. At sub-operation 1714B, the process includes evaluating durability aspects through rigorous moisture sensitivity testing, revealing water absorptions, volumetric stability and absence of shrinkage.
At operation 1716, the process includes determining the embodied carbon in the 3D printing material. The operation 1716 further includes sub-operation 1716A. At sub-operation 1716A, the process includes the determination of global warming potential and carbon footprint analysis of the 3D printing material.
Advantageously, the process for developing and printing 3D-printable construction material enables systematic replacement of conventional materials with sustainable alternatives such as GGBS, fly ash, and excavated soil content. The process further maintains consistent print quality through optimized process parameters while enabling assessment and reduction of environmental impact. Moreover, the process demonstrates versatility by accommodating various 3D-printing material combinations and replacement levels, enabling customization of mix properties for specific applications while providing flexibility in 3D printing parameter adjustment.
FIGs. 18A and 18B depict the graphical representations that illustrate the relationship between the static yield stress of the various compositions and the duration from the start of 3D printing, in accordance with an embodiment of the present disclosure. FIGs. 18A and 18B are described in conjunction with FIGs. 1 to 17. With reference to FIGs. 18A and 18B, there is shown a graphical representation 1800A that represents the relationship between the static yield stress of the different compositions and the duration from the start of 3D-printing. The different compositions, such as (CS0 (i.e., the control sample), CG30 (i.e., the 30% replacement of the sand with GGBS), CC25 (i.e., the 25% replacement of the sand with the excavated soil), CC50 (i.e., the 50% replacement of the sand with the excavated soil), CC25G30 (i.e., the 30% replacement of the sand with the GGBS and 25% with the excavated soil), and CC50G30 (i.e., the 30% replacement of the sand with the GGBS and 50% with the excavated soil). Further, the graphical representation, 1800B, represents the relationship between the static yield stress of the different compositions and the duration from the start of 3D-printing. In an exemplary scenario, the graphical representation 1800A includes an X-axis 1802A that represents the duration from the start of the 3D-printing, measured in minutes, while the Y-axis 1804A represents the static yield stress of the different compositions. Each composition is represented by a separate curve on the graphical representation 1800A, providing a comparative analysis of how the static yield stress develops over time. In an implementation, the graphical representation 1800A illustrates all the curves showing an increasing trend, signifying the gradual build-up of the static yield stress as the different compositions undergo structural stiffening during the 3D-printing process. Among the different compositions, the composition CS0 starts at the lowest yield stress and exhibits the slowest rate of increase, maintaining the lowest values of the static yield stress throughout the 3D printing process. The composition CG30 initially shows a higher static yield stress than the composition CS0. In an implementation, the compositions CS25 and CS50 demonstrate significantly higher growth rates of the static yield stress, with the composition CS50 showing rapid initial stiffening before stabilizing at around 2,500 Pa. The compositions CS25G30 and CS50G30 show the highest static yield stress, with the composition CS50G30 reaching a maximum value of approximately 2,800 Pa and confirms superior structural build-up as the higher static yield stress helps maintain stability of the 3D-printed structure after extrusion. However, the compositions, including GGBS and Fly ash, exhibit significantly higher static yield stress, confirm greater stability during 3D-printing and improve internal cohesion, preventing deformation under load and ensuring the better layer quality of the 3D-printed structures.
In another exemplary scenario, the graphical representation 1800B includes an X-axis 1802B that represents the duration from the start of 3D printing, measured in minutes, while the Y-axis 1804B represents the static yield stress of the different compositions. The graphical representation, 1800B, represents the static yield stress from the start of the 3D-printing for the different compositions, including CC0, CF30, CC25, CC50, CC25F30, and CC50F30. In an implementation, the graphical representation 1800B illustrates that the cementitious mixes containing fly ash as an additive exhibit significantly higher static yield stress compared to the cementitious mixes without additives (or control samples). The composition CS0, the control sample, shows the lowest static yield stress and lowest increase of the static yield stress over time, indicating a lower rate of structural build-up of the 3D-printed structures. The composition CF30 represents a better performance than the composition CC0 but remains lower than the composition containing additives. The compositions CC25 and CC50 containing additives represents a substantial improvement, with higher yield stresses indicating better internal cohesion and structural development of the 3D-printed structures. Furthermore, the compositions CC25F30 and CC50F30 demonstrate a faster increase in static yield stress over time, with the composition CC50F30 reaching approximately 2,800 Pa, the highest observed value. Thus, the graphical representation illustrates that the incorporation of additives in the 3D printable cementitious mixes significantly enhances structural build-up, leads to better layer quality and reduced deformation and contributes to higher buildability of the 3D-printed structures.
Examples
Example 1 An example illustrating the method for preparing the 3D-printable construction material.
Materials Used: The Ordinary Portland Cement 52.5 N, Ground Granulated Blast Furnace Slag (GGBS), Fly ash (FA) sourced from a local construction site, Excavated soil content, dried and sieved to 4.75 mm, Manufactured sand, High-range polycarboxylate-based superplasticizer, Cellulose ether-based viscosity modifier, water.
Steps to prepare the 3D-printable construction material:
1. Preparation of the raw materials
1) The excavated soil content was sourced from excavation operations, then dried at 60 ºC to constant mass, and sieved through 4.75 mm.
2) The portion of the M-sand was mixed with the OPC, GGBS, and fly ash in varying proportions as per the compositions. The compositions include the OPC-sand, the OPC-FA-sand, the OPC-GGBS-sand, the OPC-soil, the OPC-GGBS-soil, and the OPC-FA-soil.
2. Mixing the composition materials
1) The OPC, GGBS, FA, M-sand, and excavated soil content were combined in a specified binder-to-aggregate ratio.
2) The superplasticizer dosage and water content were adjusted through trials to obtain the required flowability.
3) The compositions containing excavated soil content include the viscosity modifier dosage that was reduced by 75% compared to the composition CS0 to compensate for the increased viscosity due to the presence of clay content in the excavated soil.
3. Adjusting the composition for extrusion
1) The compositions were adjusted to ensure the required extrusion properties, such as flowability and buildability in the 3D-printable construction material.
4. Preparation for 3D-printing
1) The compositions were loaded into the hopper of the three-axis gantry printer fitted with the screw extruder.
2) During the 3D printing, the stand-off distance was maintained between 16-18 mm, and the extrusion speed was set at 30 mm/s for the periphery and 60 mm/s for the infill, using a 20 mm nozzle.
5. Extrusion and deposition
1) The 3D-printed structure was built layer by layer, with a designed footprint of 350 mm x 350 mm. There were two types of 3D-printed structured were printed: one consisting of the hollow cuboid structure and the other with internal cross-bracings for enhanced structural stability.
6. Final drying and curing
1) After extrusion, the 3D-printed structures were covered with moist burlap after 3-4 hours of printing to prevent rapid moisture evaporation, ensuring the 3D-printable construction material maintains optimal strength and stability.
2) The 3D-printed structure layers were allowed to cure for a minimum of 28 days to reach the required compressive strength and structural integrity.
Example 2
An example illustrating the 3D-printing of the construction element.
Materials Used: Portland Cement, fine Aggregates of manufactured sand, excavated soil content, chemical admixtures, and water.
Steps to Prepare the 3D Printable Construction Material
1. Preparation of the raw materials
1) In the mixing container, the OPC is measured as one part by weight.
2) The fine aggregates of manufactured sand, including excavated soil content containing non-expansive clay content (25-50% by weight of the total fine aggregates), are added. The fine aggregates of manufactured sand are thoroughly mixed with OPC.
3) The first chemical admixture (polycarboxylate-based superplasticizer) is added to the compositions in an amount of 0.10-0.36% by weight of the binder.
4) The second chemical admixture (cellulose ether-based viscosity modifier) is incorporated at 0.46-2.75% by weight of the binder.
5) The Water is then added to the compositions, adjusting the water-to-binder ratio to between 0.38 and 0.55 to ensure the desired flowability and workability.
2. Mixing of Material
1. The composition is blended in a concrete mixer for 5-7 minutes to ensure uniform distribution of all the components in the composition.
2. After mixing, the composition is checked for flow spread, ensuring the composition reaches the required range of 140-150 mm at first extrusion. If necessary, the water content or chemical admixtures are adjusted to achieve the desired flow consistency.
3. Extrusion of the Construction Material
1. The prepared compositions are loaded into the 3D-printing system, which is equipped with a nozzle.
2. The compositions are extruded through the nozzle at a controlled rate based on the design specifications, ensuring proper flow and layer deposition.
4. Deposition of Layers
1. The composition is deposited onto a 3D-printing bed at the predetermined pattern, with each layer having a height of 15 - 18 mm.
2. The extrusion process is monitored to ensure that each layer is uniformly deposited and adheres well to the previous layer, ensuring structural integrity during the 3D printing process.
5. Layer Building to form the 3D-Printing Construction Element
1. The 3D-printing process continues, depositing successive layers to build up the 3D- 3D-printing construction element.
2. The layers are built up to a height of at least 1 meter, ensuring the 3D-printed structure reaches the required size and shape.
3. During the 3D-printing process, layer adhesion and structural stability are continuously monitored to ensure the quality of the 3D-printed construction element.
Example 3
Global warming potential (GWP) of the 3D-printable mixes:
There is shown the Global Warming Potential (GWP) of various compositions (i.e., CS0/CC0, CG30, CF30, CS25, CS50, CS25G30, CS50G30, CC25F30, and CC50F30), particularly in 3D-printing applications. Further, Table 1 represents the mix constituents (i.e., OPC, GGPS, FA, sand, soil, SP, and VMA) with different GWP. Furthermore, through the experimental data, the GWP for various 3D-printable mix codes was evaluated. The CS0/CC0 mix had a GWP of 710.05 kg CO2-eq/m3, while the CC50F30 mix (with 50% cement replacement by GGBS and 30% by fly ash) had a GWP of only 435.20 kg CO2-eq/m3, a reduction of over 35%. The 3D-printing process itself contributed a relatively small amount to the overall GWP, around 8.61 kg CO2-eq/m3. Thus, by strategically replacing cement with supplementary cementitious materials and leveraging the efficiency of 3D printing, the 3D printing can be done in an environmentally friendly way, potentially lowering the environmental impact by 35-40% compared to conventional construction methods.
Mix constituents GWP (kg CO2-eq/kg of material)
OPC 0.91
GGBS 0.0416
FA 0.004
Sand 0.0499
Soil 0.00499
SP 1.88
VMA (categorized as hardening accelerators) 2.28
Table 1 GWP of the mix constituents
Moreover, Table 2 represents the Global Warming Potential (GWP) of various compositions (i.e., CS0/CC0, CG30, CF30, CS25, CS50, CS25G30, CS50G30, CC25F30, and CC50F30), particularly in 3D-printing applications. The compositions that replace cement show significantly lower GWP. The CS25G30 cementitious mixture, having 25% cement and 30% GGBS, shows a GWP of 498.34 kg CO2-eq/m3. Similarly, the composition CS50G30 (50% cement, 30% GGBS) has an even lower GWP of 453.44 kg CO2-eq/m3. The composition CC25F30 (25% cement, 30% fly ash) is 484.86 kg CO2-eq/m3. The composition CC50F30 (50% cement, 30% fly ash) has the lowest GWP at 435.20 kg CO2-eq/m3 demonstrating that replacing cement with supplementary cementitious materials can reduce the GWP of 3D-printable mixes by over 35 - 40%. Thus, by replacing Ordinary Portland Cement (OPC) with supplementary cementitious materials (SCMs) such as ground granulated blast-furnace slag (GGBS) and fly ash (FA), the GWP of the 3D-printable mixes can be lowered by over 35 - 40% compared to traditional cement-based mixtures.
Mix codes GWP for material (kg CO2-eq/m3) GWP for printing process (kg CO2-eq/m3) Total GWP (kg CO2-eq/m3)
CS0/CC0 701.44

8.61 710.05
CG30 526.55 535.16
CF30 519.03 527.64
CS25 654.63 663.24
CS50 604.39 613.00
CS25G30 489.73 498.34
CS50G30 444.83 453.44
CC25F30 477.91 486.52
CC50F30 435.20
Table 2 GWP of the mix constituents and the process in kg CO2-eq/cubic meters of printable mixes.

Modifications to embodiments of the present disclosure described in the foregoing are possible without departing from the scope of the present disclosure as defined by the accompanying claims. Expressions such as “including”, “comprising”, “incorporating”, “have”, “is” used to describe, and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural. The word “exemplary” is used herein to mean “serving as an example, instance, or illustration”. Any embodiment described as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or to exclude the incorporation of features from other embodiments. The word “optionally” is used herein to mean “is provided in some embodiments and not provided in other embodiments”. It is appreciated that certain features of the present disclosure, which are, for clarity, described in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features of the invention, which are, for brevity, described in the context of a single embodiment, may also be provided separately or in any suitable combination or as suitable in any other described embodiment of the disclosure.
, Claims:CLAIMS
We claim:
1. A 3D printable construction material comprising:
one part of a binder comprising Portland cement;
two parts of fine aggregates comprising 25-50% by weight excavated soil content containing non-expansive clay;
a first chemical admixture in an amount of 0.10-0.36% by weight of the binder; and
a second chemical admixture in an amount of 0.46-2.75% by weight of the binder,
wherein the 3D printable construction material has a flow spread of 140-150 mm at first extrusion and is capable of being built up to a height of at least 1 meter when 3D printed.
2. The 3D printable construction material as claimed in claim 1, further comprising water in a water-to-binder ratio of 0.38-0.55.
3. The 3D printable construction material as claimed in claim 1, wherein the binder further comprises 30% by weight of a supplementary cementitious material selected from the group consisting of calcium-alumino-silicate-based industrial by-products.
4. The 3D printable construction material as claimed in claim 1, wherein the excavated soil content has a clay content of 42-47% and a plasticity index of 16%.
5. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material has a shape retention factor of 70-92% when 3D printed.
6. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material has a global warming potential of 435-710 kg CO2-eq/m3.
7. The 3D printable construction material as claimed in claim 1, wherein the first chemical admixture is a viscosity modifying admixture and the second chemical admixture is a superplasticizer.
8. The 3D-printable construction material as claimed in claim 1, wherein the dosage of viscosity modifying admixture is reduced by 72% due to the use of non-expansive clayey soil.
9. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material achieves a buildable height that is at least 2.5 times higher than a conventional cement-sand mix.
10. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material comprises a wet compressive strength of 10 - 28 MPa when 3D printed and cured for 28 days.
11. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material exhibits a reduction in total shrinkage of at least 30% at 56 days when compared to a conventional cement-sand mix.
12. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material exhibits an inter-layer shear bond strength of at least 4 MPa when 3D printed and cured for 28 days.
13. The 3D printable construction material as claimed in claim 1, wherein the 3D printable construction material comprises a ratio of wet strength to dry strength of at least 0.80 when 3D printed and cured.
14. A method 100 of preparing a 3D printable construction material, comprising:
collecting excavated soil content containing non-expansive clay from construction or demolition activities;
drying the excavated soil content to constant mass;
sieving the dried soil;
combining: one part by weight of a binder comprising Portland cement, two parts by weight of fine aggregates, wherein 25-50% by weight of the fine aggregates is the sieved excavated soil content, a first chemical admixture in an amount of 0.10-0.36% by weight of the binder, a second chemical admixture in an amount of 0.46-2.75% by weight of the binder, and water in a water-to-binder ratio of 0.38-0.55;
mixing the combined ingredients to form a 3D printable construction material having a flow spread of 140-150 mm at first extrusion, wherein the 3D printable construction material is capable of being built up to a height of at least 1 meter when 3D printed.
15. A method (200) of 3D printing a construction element, comprising:
preparing a 3D printable construction material by combining: one part by weight of a binder comprising Portland cement, two parts by weight of fine aggregates, wherein 25-50% by weight of the fine aggregates is excavated soil content containing non-expansive clay, a first chemical admixture in an amount of 0.10-0.36% by weight of the binder, a second chemical admixture in an amount of 0.46-2.75% by weight of the binder, and water in a water-to-binder ratio of 0.38-0.55;
mixing the combined ingredients to form a 3D printable construction material having a flow spread of 140-150 mm at first extrusion;
extruding the 3D printable construction material through a nozzle at a predefined rate;
depositing layers according to a predetermined pattern at a layer height of 15-18 mm; and
building up the layers to form the construction element to a height of at least 1 meter.
16. The method (200) as claimed in claim 15, wherein the predetermined printing geometry includes internal bracing structures.
17. The method (200) as claimed in claim 15, further comprising optimizing printing parameters including stand-off distance, printing speed, and layer height to achieve the shape retention factor of 70-92%.