Description:TECHNICAL FIELD
[0001] The present invention relates to the field of construction materials. In particular, it relates to a method for preparing a fabric-reinforced engineered geopolymer mortar (FREGM) composite, thereby providing an environmentally sustainable, mechanically enhanced material suitable for structural strengthening and retrofitting applications in concrete infrastructure.

BACKGROUND
[0002] Background description includes information that may be useful in understanding the present disclosure. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed disclosure, or that any publication specifically or implicitly referenced is prior art.
[0003] The durability and structural integrity of aging concrete infrastructure, including bridges, buildings, tunnels, and industrial facilities, have become significant concerns in the construction industry. Environmental exposure, chemical attack, thermal degradation, and increasing service loads often lead to deterioration, necessitating effective strengthening and retrofitting solutions.
[0004] Conventional strengthening techniques have commonly employed fibre-reinforced polymers (FRPs) and textile or fabric-reinforced cementitious matrix systems. While FRP systems offer high strength-to-weight ratios, FRPs are limited with poor fire resistance, susceptibility to moisture, high cost of epoxy resins, and incompatibility with wet or low-temperature substrates. Textile or fabric-reinforced cementitious matrix systems have emerged as alternatives that improve ductility and reduce spalling; however, the fabric reinforced matrix systems are still cement-based and contribute to significant CO₂ emissions associated with cement production. Additionally, the performance in aggressive thermal and chemical environments remains limited.
[0005] Geopolymer technology, based on the alkali activation of aluminosilicate-rich industrial and agricultural by-products, has attracted attention as a sustainable alternative to Portland cement. Geopolymer exhibit excellent chemical resistance, thermal stability, and lower carbon footprints. However, traditional geopolymer mortars exhibit brittle behavior and limited tensile capacity, which restrict their structural applications.
[0006] There is, therefore a need to provide a sustainable, robust and environment friendly mortar composition and a method for preparing the geopolymer composite with higher strengths and performance.

OBJECTS OF THE INVENTION
[0007] Some of the objects of the present disclosure, which at least one embodiment herein satisfies are as listed herein below.
[0008] A general object of the present disclosure is to provide a method for preparing a geopolymer composite integrated with fibers, thereby enhancing the tensile strength, flexural performance, and crack resistance of the material.
[0009] Another object of the present disclosure is to provide the method for preparing the geopolymer composite using industrial and agricultural waste materials, thereby promoting sustainable construction practices.
[0010] Another object of the present disclosure is to provide the geopolymer composite that can be applied using a hand layup technique for cast-in-place or prefabricated strengthening, thereby simplifying installation and reducing construction time and labor costs.
[0011] Yet another object of the present disclosure is to provide the geopolymer composite with high thermal stability and chemical resistance, thereby ensuring long-term durability in aggressive environmental conditions.

SUMMARY
[0012] Aspects of the present disclosure relates to the field of construction materials. In particular, it relates to a method for preparing a fabric-reinforced engineered geopolymer mortar composite, thereby providing an environmentally sustainable, mechanically enhanced material suitable for structural strengthening and retrofitting applications in concrete infrastructure.
[0013] An aspect of the present disclosure relate to a method for preparing a geopolymer composite. The method may include mixing a predetermined amount of one or more precursors with an alkaline activating solution to prepare a geopolymer mortar, incorporating a predetermined volume fraction of plurality of fibres into the geopolymer mortar to form an engineered geopolymer mortar and embedding at least one fabric layer within the engineered geopolymer mortar to prepare the geopolymer composite.
[0014] In an embodiment, the one or more precursors may be selected from any or a combination of: fly ash, Ground Granulated Blast Furnace Slag (GGBFS), and Sugarcane Bagasse Ash (SCBA).
[0015] In an embodiment, the alkaline activating solution may include a predetermined ratio of sodium hydroxide solution and sodium silicate solution.
[0016] In an embodiment, the method may include mixing a predetermined amount of one or more raw materials along with the plurality of fibres to prepare the engineered geopolymer mortar.
[0017] In an embodiment, the method may include mixing a predetermined amount of alkaline activating solution to prepare the engineered geopolymer mortar.
[0018] In an embodiment, the method may include mixing a predetermined amount of saturated surface dry condition sand having size less than 200 micrometers to prepare the engineered geopolymer mortar.
[0019] In an embodiment, the at least one fabric layer may be composed of an alkali-resistant glass fibre arranged in a grid configuration.
[0020] In an embodiment, each of the at least one fabric layer may be embedded at predefined intervals within the engineered geopolymer mortar.
[0021] In an embodiment, the method may include applying the geopolymer composite to a concrete surface using a hand layup technique.
[0022] In an embodiment, the method may include curing the geopolymer composite after applying the geopolymer composite to the concrete surface.
[0023] Another embodiment of the present disclosure pertains to a geopolymer composition. The geopolymer composition may include a predetermined amount of one or more precursors, an alkaline activating solution, including a predetermined ratio of sodium hydroxide solution and sodium silicate solution, a predetermined volume fraction of plurality of fibres, a predetermined amount of one or more raw materials, and at least one fabric layer. The at least one fabric layer may be embedded in a mixture of the one or more precursors, the alkaline activating solution, the one or more raw materials and the plurality of fibres to form the geopolymer composite.
[0024] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.

BRIEF DESCRIPTION OF DRAWINGS
[0025] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the present disclosure and, together with the description, serve to explain the principles of the present disclosure.
[0026] FIG. 1 illustrates an exemplary flow diagram representing a method for preparing a geopolymer composite, in accordance with an embodiment of the present disclosure.
[0027] FIG. 2 illustrates an example flow diagram of the method of a geopolymer mortar, in accordance with an embodiment of the present disclosure.
[0028] FIGs. 3A and 3B illustrate exemplary view of the geopolymer composite applied on the concrete surface, in accordance with an embodiment of the present disclosure.
[0029] FIGs. 4A to 4C illustrate graphical representation of strength properties of an engineered geopolymer mortar, in accordance with an embodiment of the present disclosure.
[0030] FIG. 5 illustrates a graphical representation of flexural strength of the fabric reinforced geopolymer mortar composite, in accordance with an embodiment of the present disclosure.
[0031] FIG. 6 illustrates an example graphical representation of compressive strength of cylinder specimens strengthen using the geopolymer composite, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION
[0032] The following is a detailed description of embodiments of the disclosure depicted in the accompanying drawings. The embodiments are in such detail as to clearly communicate the disclosure. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure as defined by the appended claims.
[0033] Embodiments of the present disclosure relates to the field of construction materials. In particular, it relates to a method for preparing a fabric-reinforced engineered geopolymer mortar composite, thereby providing an environmentally sustainable, mechanically enhanced material suitable for structural strengthening and retrofitting applications in concrete infrastructure.
[0034] An embodiment of the present disclosure relate to a method for preparing a geopolymer composite. The method may include mixing a predetermined amount of one or more precursors with an alkaline activating solution to prepare a geopolymer mortar, incorporating a predetermined volume fraction of plurality of fibres into the geopolymer mortar to form a engineered geopolymer mortar and embedding at least one fabric layer within the engineered geopolymer mortar to prepare the fabric reinforced engineered geopolymer mortar composite.
[0035] FIG. 1 illustrates an exemplary flow diagram representing a method 100 for preparing a geopolymer composite, in accordance with an embodiment of the present disclosure.
[0036] Referring to FIG. 1, at block 102, the method 100 may include mixing a predetermined amount of precursors with an alkaline activating solution to prepare a geopolymer mortar. The precursors may be selected from any or a combination of: fly ash, Ground Granulated Blast Furnace Slag (GGBFS), and Sugarcane Bagasse Ash (SCBA). The predetermined amount of precursors may be such as 60% of fly ash, 10% of SCBA and 30% of GGBFS. The alkaline activating solution may include a predetermined ratio of sodium hydroxide (NaOH) solution and sodium silicate (Na2SiO3) solution. The predetermined ratio of Na2SiO3 to NaOH may be 2. The ratio of alkaline solution to precursor may be 0.6. For preparing the geopolymer mortar, a 12 molar NaOH solution may be prepared 24 hours before mixing the precursors and the alkaline activating solution. The mixture may be blended thoroughly to initiate the geopolymerization reaction, resulting in a uniform and workable geopolymer mortar.
[0037] In an embodiment, the method 100 may include mixing a predetermined amount of raw materials to the prepared geopolymer mortar. The raw materials may be such as natural sand of saturated surface dry condition having size less than 200 micrometres. The dry materials were mixed in a mechanical mixer for 1 minute. Further, the method 100 may include mixing the predetermined amount of alkaline activating solution to the prepared geopolymer mortar. The alkaline activating solution along with the dry materials were mixed in the mechanical mixer for 3 minutes for uniform distribution of all the materials.
[0038] At block 104, the method 100 may include incorporating a predetermined volume fraction of fibres into the geopolymer mortar to form an engineered geopolymer mortar. The fibres may be polypropylene (PP) fibres, selected for their ability to improve ductility, toughness, and crack resistance of the engineered geopolymer mortar. The fibres may be added at a volume fraction of approximately 1.5%. The fibres may be gradually introduced into the mix and blended at a slow speed to ensure uniform dispersion and to prevent clumping or balling. The resulting engineered geopolymer mortar may exhibit improved strain-hardening behaviour and resistance to microcrack propagation.
[0039] In an embodiment, the polypropylene fibres may be added after initial mixing of the mortar to avoid fibre entanglement and improve distribution. The fibres may be 6 mm in length and approximately 25 micrometer in diameter, contributing to a three-dimensional network within the mortar. The uniform distribution of fibres within the mortar helps to bridge cracks and enhances the post-crack performance under tensile and flexural loads.
[0040] At block 106, the method 100 may include embedding fabric layers within the engineered geopolymer mortar to prepare the geopolymer composite. The fabric layers may be composed of an alkali-resistant glass fibre arranged in a grid configuration. The fabric layers may have a grid size of 5 millimetres x 5 millimetres. Each of the fabric layers may be embedded at predefined intervals within the engineered geopolymer mortar. The number of fabric layers may range from 1 to 5, depending on the desired structural performance. The layers may be placed manually during casting by alternating the geopolymer mortar and fabric sheets to ensure complete impregnation and bonding between the mortar and reinforcement.
[0041] The properties of the alkali-resistant glass fibre fabric is shown in Table 1.

Table 1
[0042] In an embodiment, the method 100 may include applying the geopolymer composite to a concrete surface using a hand layup technique. The hand lay-up method may involve successive placement of mortar and fabric layers onto the prepared concrete surface or a mold. The mortar may be applied manually using hands or with the help of rollers to ensure proper impregnation and bonding. The surface of the concrete may first be cleaned and roughened to improve mechanical interlock and bond strength. The geopolymer composite may be applied in successive layers of engineered geopolymer mortar and fabric, compacted gently to eliminate air voids and ensure good adhesion. Further, the method 100 may include curing the geopolymer composite after applying it to the concrete surface under ambient temperature conditions for at least 24 hours. The curing may eliminate a need for thermal curing, reduces energy consumption, and enhances on-site applicability. The cured composite may provide enhanced structural performance, environmental resistance, and long-term durability.
[0043] FIG. 2 illustrates an example flow diagram 200 of the method of a geopolymer mortar, in accordance with an embodiment of the present disclosure.
[0044] Referring to FIG. 2, at step 202, the precursors and the raw materials may be selected, including fly ash, GGBFS, SCBA, and fine sand as the aggregate. The dry materials may be blended to form the base of the geopolymer mortar. At step 204, the dry materials may be subjected to initial mixing to ensure uniform distribution and may be done manually or in a mixer. At step 206, the alkaline activating solution may be prepared separately using sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) in the predetermined ratio, initiating the geopolymerization process. At step 208, the dry mixture and the activating solution may be added together and mixed thoroughly using the mechanical mixer to form a homogenous geopolymer mortar. The polypropylene (PP) fibres may be added to mixer to produce engineered geopolymer mortar for improved ductility and crack resistance.
[0045] In an embodiment, at step 210, the fresh mortar may be poured into prepared moulds of various geometries, depending on the type of mechanical tests to be conducted (e.g., cubes, cylinders, prisms). At step 212, the filled mould may undergo compaction using a mechanical vibrator to remove entrapped air and ensure a dense, uniform mortar. At step 214, the mortar in the mould may be allowed to undergo curing in ambient temperatures. At step 216, after 24 hours of ambient curing, the specimens may be demoulded and left to continue curing under ambient temperature to achieve the desired mechanical strength. At step 218, the fully cured specimens may be used for testing. The specimens may be subjected to mechanical testing using a universal testing machine (UTM) or other relevant apparatus to evaluate properties such as compressive strength, flexural strength, tensile capacity, strain-hardening behavior and the like.
[0046] FIGs. 3A and 3B illustrate exemplary views 300A and 300B of the geopolymer composite applied on the concrete surface, in accordance with an embodiment of the present disclosure.
[0047] Referring to FIGs. 3A and 3B, the fabric layer 302 embedded in the engineered geopolymer mortar 304 may externally bonded and applied to a concrete surface 306 (such as a concrete beam or a concrete cylinder) to enhance the strength and performance of the concrete beam under bending loads. The partially cut-out section reveals the embedded alkali-resistant (AR) glass fabric layer 302 in a grid configuration within the engineered geopolymer mortar 304, forming a composite laminate.
[0048] FIGs. 4A to 4C illustrate graphical representations of strength properties of the engineered geopolymer mortar 304, in accordance with an embodiment of the present disclosure. The developed engineered geopolymer mortar (EGM) 304 with 1%, 1.5%, and 2% PP fiber may be named as EGM1, EGM1.5 and EGM2 respectively.
[0049] Referring to FIGs. 4A to 4C, based on experimentation, maximum compressive strength obtained as 58.76 MPa for PP fiber of 1.5% volume fraction. Minimum compressive strength pf 40.3 MPa obtained for 2% PP fiber on 28th day. All EGM specimens may attain more strength than the normal geopolymer mortar except for EGM2. The 1.5% of PP fiber possesses 15.66% higher strength compared to normal geopolymer mortar, and 1% PP fiber increased 6.8% compressive strength. On the other hand, compressive strength of EGM2 was about 20.66% lower than the geopolymer mortar. Addition of PP fiber increasing beyond a limit may reduce the compressive strength. About 31.42% reduction in strength may occur in EGM2 specimen while comparing with EGM1.5. The excessive fiber may lead to the introduction of more interfaces. In addition, high fiber quantity may lead to air entrainment and affect the bonding between fiber and geopolymer mortar. Also, the addition of excessive fiber may result in uneven mortar formation. According to the experiments conducted, the suitable percentage of addition of PP fiber is 1.5%.
[0050] Further, the inclusion of PP fiber has significant effect on flexural strength. The minimum flexural strength was obtained about 10.2 MPa for the EGM2 geopolymer sample over 28 days. The maximum flexural strength was reported for the EGM1.5 and is about 46.6% higher strength than the normal geopolymer. More than 50% of flexural strength was achieved in the first 7 days of the curing period due to the strong formation of the geopolymer mortar. Further addition of PP fiber decreased the flexural strength. Increasing the fiber content may cause low workability and may turn poor dispersion of fiber in the mortar which will effects the microstructure. The addition of different percentages of PP fiber revealed that 1.5% PP fiber addition may be the optimum fiber content and provides good interaction with the geopolymer gel results in efficient mechanical performance.
[0051] Further, split tensile strength values significant improvements is clearly visible up to EGM1.5. Maximum split tensile strength was attained by EGM1.5 specimen. Lowest split tensile strength value reported was 2.43 MPa for the specimen EGM2 at 28th day. The 2% PP fiber included samples split tensile strength may be lesser than the split tensile strength of specimens with 1% PP fiber. About 6% strength increment was observed for the EGM1.5 specimen when compared to geopolymer mortar. More than 50% of split tensile strength was obtained over the first 7 days of the ambient curing period. The increase in split tensile value resulting from the addition of 1.5% fiber may be attributed to the denser microstructure, formed by the incorporation of SCBA in the geopolymer mix, facilitating effective stress transfer to the fibers.
[0052] FIG. 5 illustrates a graphical representation of flexural strength of the fabric reinforced engineered geopolymer mortar composite, in accordance with an embodiment of the present disclosure.
[0053] Referring to FIG. 5, based on experimentation on fabric reinforced engineered geopolymer mortar composite beams with different fabric layers, maximum strength was obtained for FREGM4 (beam with 4 layers of fabric layers) specimen. FREGM4 exhibited about 33.33% higher flexural strength than the FREGM1 (beam with one layer of fabric) specimen. Even though there may be a gradual increase in the flexural strength of specimens with increasing fabric layers, specimens with 5 layers of fabric exhibit lower flexural strength than those with 4 layers. Decreasing the spacing between the layers beyond a limit may adversely affect the flexural strength. The maximum flexural strength of 4 layers specimen achieved more strength than the specimen with 5 layers.
[0054] FIG. 6 illustrates an example graphical representation of compressive strength of cylinder specimens strengthen using the geopolymer composite, in accordance with an embodiment of the present disclosure.
[0055] Referring to FIG. 6, maximum axial stress may be obtained for the specimen strengthened with two layers of fabrics. Up to 30% of axial stress increased by the 2-layer confinement samples (FP02L). Specimens cast using the cast-in-place method (monolithic casting) may exhibit higher axial stress compared to precast cylinder specimens with confinement. The higher axial stress may be attributed to an effective bonding between the confinement layer and the cylinder specimens used in the monolithic casting. FP0L (no layers) and FP1L (single layer confinement) specimens may have a precast cylinder and no AR glass layer and one AR glass layer, respectively. FC1L specimens may have one layer AR Glass layer, a core cylinder and strengthening layers casted at the same time.
[0056] Thus, the present disclosure introduces a method for preparing a geopolymer composite using fabric layers embedded within the engineered geopolymer mortar 304. The method may enhance mechanical properties such as tensile and flexural strength, improve durability and crack resistance, and enable sustainable construction practices. The fabric-reinforced engineered geopolymer mortar composite may be applied to various structural elements using a hand layup technique, making it suitable for strengthening and retrofitting applications in beams, columns, and other load-bearing components.
[0057] While the foregoing describes various embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof. The scope of the disclosure is determined by the claims that follow. The disclosure is not limited to the described embodiments, versions or examples, which are included to enable a person having ordinary skill in the art to make and use the disclosure when combined with information and knowledge available to the person having ordinary skill in the art.

ADVANTAGES OF THE INVENTION
[0058] The present disclosure provides a geopolymer composite that utilizes industrial and agricultural waste materials, thereby significantly reducing carbon emissions and promoting eco-friendly construction.
[0059] The present disclosure provides a fiber and fabric-reinforced geopolymer mortar that exhibits superior tensile and flexural strength, thereby enhancing the load-bearing capacity and mechanical performance of strengthened structural elements.
[0060] The present disclosure provides the geopolymer composite with improved thermal and chemical resistance, thereby making it suitable for applications in high-temperature environments, marine structures, and chemically aggressive settings.
[0061] The present disclosure provides a method of preparing the geopolymer composite using a simple hand layup technique, thereby facilitating easy on-site application for both cast-in-place and precast retrofitting.
[0062] The present disclosure provides a durable and crack-resistant composite material with strain-hardening characteristics, thereby extending the service life of existing infrastructure and improving structural resilience under mechanical stress.
, Claims:1. A method (100) of preparing a geopolymer composite, the method (100) comprising:
mixing (102) a predetermined amount of one or more precursors with an alkaline activating solution to prepare a geopolymer mortar;
incorporating (104) a predetermined volume fraction of plurality of fibres into the geopolymer mortar to form an engineered geopolymer mortar (304); and
embedding (106) at least one fabric layer (302) within the engineered geopolymer mortar (304) to prepare the geopolymer composite.
2. The method (100) as claimed in claim 1, wherein the one or more precursors are selected from any or a combination of: fly ash, Ground Granulated Blast Furnace Slag (GGBFS), and Sugarcane Bagasse Ash (SCBA).
3. The method (100) as claimed in claim 1, wherein the alkaline activating solution comprises a predetermined ratio of sodium hydroxide solution and sodium silicate solution.
4. The method (100) as claimed in claim 1, comprising mixing a predetermined amount of one or more raw materials to prepare the engineered geopolymer mortar (304).
5. The method (100) as claimed in claim 1, comprising mixing a predetermined amount of alkaline activating solution, to prepare the engineered geopolymer mortar (304).
6. The method (100) as claimed in claim 1, comprising mixing a predetermined amount of saturated surface dry condition sand having size less than 200 micrometers to prepare the engineered geopolymer mortar (304).
7. The method (100) as claimed in claim 1, wherein the at least one fabric layer (302) is composed of an alkali-resistant glass fibre arranged in a grid configuration.
8. The method (100) as claimed in claim 1, wherein each of the at least one fabric layer (302) is embedded at predefined intervals within the engineered geopolymer mortar (304).
9. The method (100) as claimed in claim 1, comprising applying the geopolymer composite to a concrete surface (306) using a hand layup technique.
10. The method (100) as claimed in claim 9, comprising curing the geopolymer composite after applying the geopolymer composite to the concrete surface (306).
11. A geopolymer composite, comprising:
a predetermined amount of one or more precursors;
an alkaline activating solution, comprising a predetermined ratio of sodium hydroxide solution and sodium silicate solution;
a predetermined volume fraction of plurality of fibres;
a predetermined amount of one or more raw materials; and
at least one fabric layer (302),
wherein the at least one fabric layer is embedded in a mixture of the one or more precursors, the alkaline activating solution, the one or more raw materials and the plurality of fibres to form the geopolymer composite.