Description:DESCRIPTION:
Field of the invention:
[0001] The present disclosure generally relates to the technical field of civil engineering materials and concrete technology, in specific, relates to a self-compacting concrete composition that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications.
Background of the invention:
[0002] Self-compacting concrete (SCC) is a specialized type of concrete that flows under its own weight, filling formwork and achieving full compaction without the need for external vibration. SCC is developed to address labor shortages and improve the durability of concrete structures by minimizing voids, particularly in areas with congested reinforcement. Its unique properties, including high flowability, passing ability, and resistance to segregation, have made it a preferred material in modern construction, especially for complex structural designs. However, achieving these properties requires careful mix design, balancing the proportions of cement, aggregates, water, and chemical admixtures to ensure both workability and mechanical strength.

[0003] The development of SCC has relied heavily on the use of supplementary cementitious materials (SCMs) to enhance its performance and sustainability. SCMs, such as fly ash, silica fume, and ground granulated blast furnace slag (GGBFS), are often incorporated to reduce the environmental impact of cement production, which is a significant source of carbon dioxide emissions. These materials, typically industrial by-products, contribute to the pozzolanic reactions that improve the long-term strength and durability of concrete. GGBFS, a residue from steel production, is particularly valued for its ability to enhance workability and reduce the heat of hydration, though its incorporation can affect the early strength and setting time of concrete mixes.

[0004] The fresh properties of SCC, such as slump flow, viscosity, and passing ability, are critical to its performance in construction applications. Achieving optimal flowability while preventing segregation requires precise control over the mix constituents, including the water-to-binder ratio and the use of superplasticizers. Superplasticizers, often polycarboxylate ether (PCE)-based, are essential for dispersing cement particles and improving the fluidity of the mix. However, the interaction between superplasticizers and SCMs can sometimes lead to challenges, such as delayed setting times or reduced early strength, necessitating further research into optimizing these interactions for consistent performance.

[0005] Recent advancements in concrete technology have explored the use of nanomaterials to further enhance the properties of SCC. Nano-silica, due to its high specific surface area and reactivity, has emerged as a promising additive for improving the microstructure of concrete. By promoting pozzolanic reactions and filling micro-voids, nano-silica can enhance compressive strength, reduce permeability, and improve the interfacial transition zone (ITZ) between aggregates and cement paste. However, the incorporation of nano-silica often requires adjustments to the mix design, as its high surface area can increase water demand and affect workability, posing challenges for maintaining the desired flow characteristics of SCC.

[0006] The mechanical properties of SCC, including compressive, tensile, and flexural strengths, are influenced by the type and proportion of SCMs and additives used. While GGBFS can improve long-term strength, its effect on early strength is often limited, and excessive replacement of cement with GGBFS may lead to reduced flowability or alkali-silica reactions. Similarly, the addition of nano-silica, while beneficial for strength, can reduce slump flow due to its water-absorbing properties, requiring careful calibration of admixtures. These trade-offs highlight the need for innovative mix designs that balance workability and strength while incorporating sustainable materials.

[0007] Environmental considerations have driven the increased use of industrial by-products like GGBFS in concrete production. By reducing the reliance on ordinary Portland cement (OPC), these materials help mitigate the environmental footprint of construction activities. However, the variability in the chemical composition and fineness of GGBFS can affect the consistency of concrete performance, necessitating standardized guidelines for its use in SCC. The development of such guidelines has facilitated the adoption of SCC in diverse construction applications, but challenges remain in optimizing mixes for specific performance requirements.

[0008] The integration of nanomaterials like nano-silica into SCC has opened new avenues for research, particularly in understanding their impact on hydration kinetics and microstructure development. The pozzolanic reactivity of nano-silica leads to the formation of additional calcium silicate hydrate (C-S-H) gel, which strengthens the cement matrix. However, the high reactivity of nano-silica can also lead to rapid consumption of calcium hydroxide, affecting the early hydration process and setting behavior. Achieving a balance between early and long-term strength gains remains a key challenge in the development of nano-silica-enhanced SCC.

[0009] Despite the advancements in SCC mix design, there is a continuous need for methods that improve both the fresh and hardened properties of concrete while maintaining cost-effectiveness and sustainability. Existing approaches often face limitations, such as the need for high dosages of superplasticizers or the trade-off between workability and strength when using SCMs and nanomaterials. These challenges underscore the importance of developing innovative mix designs that address these limitations, offering enhanced performance for modern construction demands.

[0010] By addressing all the above-mentioned problems, there is a need for a self-compacting concrete composition that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications. There is a need for a self-compacting concrete composition that integrates ordinary Portland cement, ground-granulated blast-furnace slag, and colloidal nano-silica solids added with their liquid fraction to form a balanced grade-30 binder system. There is also a need for a self-compacting concrete composition that exhibits enhanced split-tensile and flexural strengths, thereby improving crack resistance and overall structural performance. There is also a need for a self-compacting concrete composition that consistently satisfies flowability, viscosity, and passing-ability criteria, streamlining production for precast, ready-mix, and in-situ applications. Further, there is also a need for a self-compacting concrete composition that offers a cost-effective, high-performance, and industrially scalable solution, thereby fostering faster construction cycles and longer service life of civil structures.
Objectives of the invention:
[0011] The primary objective of the present invention is to provide a self-compacting concrete composition that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications.

[0012] Another objective of the present invention is to provide a self-compacting concrete composition that integrates ordinary Portland cement, ground-granulated blast-furnace slag, and colloidal nano-silica solids added with their liquid fraction to form a balanced grade-30 binder system.

[0013] Another objective of the present invention is to provide a self-compacting concrete composition that achieves a slump-flow diameter of at least 650 mm, thereby enabling placement without mechanical vibration even in heavily reinforced sections.

[0014] Another objective of the present invention is to provide a self-compacting concrete composition that delivers a minimum 8 % increase in 28-day compressive strength over a reference SCC mix containing no nano-silica.

[0015] Another objective of the present invention is to provide a self-compacting concrete composition that exhibits enhanced split-tensile and flexural strengths, thereby improving crack resistance and overall structural performance.

[0016] Another objective of the present invention is to provide a self-compacting concrete composition that reduces ordinary Portland cement usage by 20 % through GGBFS substitution, thereby lowering embodied CO₂ and supporting sustainable construction practices.

[0017] Another objective of the present invention is to provide a self-compacting concrete composition whose nano-silica densifies the micro-structure, decreases permeability, and extends durability against aggressive environments.

[0018] Yet another objective of the present invention is to provide a self-compacting concrete composition that consistently satisfies flowability, viscosity, and passing-ability criteria, streamlining production for precast, ready-mix, and in-situ applications.

[0019] Further objective of the present invention is to provide a self-compacting concrete composition that offers a cost-effective, high-performance, and industrially scalable solution fostering faster construction cycles and longer service life of civil structures.
Summary of the invention:
[0020] The present disclosure proposes a self-compacting concrete composition with improved mechanical strength properties and method of preparation. The following presents a simplified summary in order to provide a basic understanding of some aspects of the claimed subject matter. This summary is not an extensive overview. It is not intended to identify key/critical elements or to delineate the scope of the claimed subject matter. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0021] In order to overcome the above deficiencies of the prior art, the present disclosure is to solve the technical problem to provide a self-compacting concrete composition that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications.

[0022] According to one aspect, the invention provides a self-compacting concrete composition. The self-compacting concrete composition comprises 15 to 20 weight percentage of ordinary Portland cement (OPC), 4 to 6 weight percentage of ground granulated blast furnace slag (GGBFS), 0.1 to 0.2 weight percentage of colloidal nano-silica solid, 0.2 to 0.3 weight percentage of colloidal nano-silica liquid, 7.5 to 9.5 weight percentage of water, 32 to 36 weight percentage of fine aggregate, 34 to 38 weight percentage of coarse aggregate, 0.1 to 0.2 weight percentage of polycarboxylate ether (PCE)-based superplasticizer, whereby the self-compacting concrete composition, when mixed and cured, exhibits superior compressive, split tensile, and flexural strength performance, and demonstrates enhanced slump flow, viscosity, and passing ability for self-compacting applications.

[0023] The self-compacting concrete composition comprises 17.59 weight percentage of the ordinary Portland cement (OPC), 4.42 weight percentage of the ground granulated blast furnace slag (GGBFS), 0.11 weight percentage of the colloidal nano-silica solids, 0.23 weight percentage of the colloidal nano-silica liquid, 8.40 weight percentage of the water, 33.51 weight percentage of the fine aggregate, 35.63 weight percentage of the coarse aggregate, and 0.15 weight percentage of the polycarboxylate ether (PCE)-based superplasticizer.

[0024] In one embodiment herein, the self-compacting concrete composition comprises 32% nano-silica solids and 68% nano-silica liquids and is configured to be added such that its solid fraction is incorporated into the binder phase and its liquid fraction is added to the mixing water, thereby enabling consistent binder-to-water proportioning and balanced pozzolanic reactivity. In one embodiment herein, the colloidal nano-silica solids are present at an optimum dosage of at least 1.5 weight percentage of total binder content, corresponding to a total colloidal nano-silica input of 7.93 kg/m³.

[0025] In one embodiment herein, the OPC, the GGBFS, and the colloidal nano-silica solids collectively form a binder phase of the self-compacting concrete composition. In one embodiment herein, the water is incorporated in a quantity such that the water-to-binder ratio is maintained at 0.38, thereby optimizing hydration, rheology, and mechanical strength properties.

[0026] In one embodiment herein, the fine aggregate comprises natural river sand conforming to Zone II gradation, and the coarse aggregate comprises crushed stone with a nominal maximum size of 10 mm. In one embodiment herein, the PCE-based superplasticizer includes a viscosity-modifying admixture, thereby improving steric repulsion, enhancing dispersion of nano-silica particles, and maintaining workability over time.

[0027] In one embodiment herein, the self-compacting concrete composition is formulated to meet the requirements of grade 30 self-compacting concrete and achieves a target compressive strength of at least 38.25 N/mm² at 28 days. In one embodiment herein, the self-compacting concrete composition demonstrates at least a 10% increase in compressive strength at 7 days and at least a 15% increase at 91 days, relative to a reference SCC mix without nano-silica. In one embodiment herein, the self-compacting concrete composition exhibits at least 20% improvement in split tensile strength and at least 10% improvement in flexural strength at 28 days, thereby enhancing ductility and crack resistance in structural members. In one embodiment herein, the self-compacting concrete composition exhibits a slump flow of at least 730 mm, a V-funnel flow time below 10 seconds, and a passing ability (L-box ratio) of 1.00.

[0028] According to another aspect, the invention provides a method for preparing the self-compacting concrete composition. At one step, the ordinary Portland cement (OPC) 102, the ground granulated blast furnace slag (GGBFS), and the colloidal nano-silica solids having 32% active nano solids are weighed and mixed to form a binder mixture. At another step, the fine aggregate, which includes natural river sand conforming to Zone II grading, and the coarse aggregate, which includes crushed stone with the nominal maximum size of at least 10 mm, are weighed and prepared, then the prepared fine aggregate and the coarse aggregate are added to the binder mixture.

[0029] At another step, 68% of colloidal nano-silica liquids are measured and mixed with the water to obtain a water mixture, and the total water content is adjusted to maintain a water-to-binder ratio of at least 0.38. At another step, the polycarboxylate ether (PCE)-based superplasticizer with viscosity-modifying properties is measured and mixed into the water mixture to form a homogenized liquid solution. At one step, the binder mixture, the fine aggregate, and the coarse aggregate are mixed in a mechanical concrete mixer for a predetermined time period to ensure uniform distribution, thereby obtaining a dry mixture.

[0030] At another step, the homogenized liquid solution is added into the dry mixture under continuous mixing in the mechanical concrete mixer for a predetermined time period to form the self-compacting concrete composition. At another step, the prepared self-compacting concrete composition is discharged into formwork without vibration, thereby allowing it to self-level and fill the mold through gravitational flow and internal cohesion. Further, at other step, the self-compacting concrete composition is cured under standard moist curing conditions at a predetermined temperature and relative humidity for at least 7 to 91 days, thereby achieving the slump flow of at least 730 mm, the passing ability ratio of 1.00, the viscosity of 8 seconds, and enhanced compressive strength, split tensile strength, and flexural strength compared to a reference self-compacting concrete lacking colloidal nano-silica.

[0031] Further, objects and advantages of the present invention will be apparent from a study of the following portion of the specification, the claims, and the attached drawings.
Detailed description of drawings:
[0032] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, explain the principles of the invention.

[0033] FIG. 1 illustrates a block diagram depicting a self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.

[0034] FIG. 2 illustrates a screenshot depicting a flow table equipment evaluating slump flow behavior of the self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.

[0035] FIG. 3 illustrates a screenshot depicting a sump flow measurement of the self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.

[0036] FIG. 4 illustrates a screenshot depicting a passing ability test of the self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.

[0037] FIG. 5 illustrates a screenshot depicting a viscosity test of the self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.

[0038] FIG. 6 illustrates a graph depicting a variation of compressive strength of the self-compacting concrete composition at 7, 28, and 91 days, in accordance to an exemplary embodiment of the invention.

[0039] FIG. 7 illustrates a graph depicting a variation of split tensile strength of the self-compacting concrete composition at 7, 28, and 91 days, in accordance to an exemplary embodiment of the invention.

[0040] FIG. 8 illustrates a graph depicting a variation of flexural strength of the self-compacting concrete composition at 7, 28, and 91 days, in accordance to an exemplary embodiment of the invention.

[0041] FIG. 9 illustrates a flowchart of a method for preparing the self-compacting concrete composition, in accordance to an exemplary embodiment of the invention.
Detailed invention disclosure:
[0042] Various embodiments of the present invention will be described in reference to the accompanying drawings. Wherever possible, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps.

[0043] The present disclosure has been made with a view towards solving the problem with the prior art described above, and it is an object of the present invention to provide a self-compacting concrete composition that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications.

[0044] According to an exemplary embodiment of the invention, FIG. 1 refers to a block diagram depicting a self-compacting concrete composition 100. The self-compacting concrete composition 100 consistently satisfies flowability, viscosity, and passing-ability criteria, streamlining production for precast, ready-mix, and in-situ applications. The self-compacting concrete composition 100 offers a cost-effective, high-performance, and industrially scalable solution, fostering faster construction cycles and longer service life of civil structures.

[0045] The self-compacting concrete composition 100 comprises 15 to 20 weight percentage of ordinary Portland cement (OPC) 102, 4 to 6 weight percentage of ground granulated blast furnace slag (GGBFS) 104, 0.1 to 0.2 weight percentage of colloidal nano-silica solids 106, 0.2 to 0.3 weight percentage of colloidal nano-silica liquid 108, 7.5 to 9.5 weight percentage of water 110, 32 to 36 weight percentage of fine aggregate 112, 34 to 38 weight percentage of coarse aggregate 114, 0.1 to 0.2 weight percentage of polycarboxylate ether (PCE)-based superplasticizer 116, whereby the self-compacting concrete composition 100, when mixed and cured, exhibits superior compressive, split tensile, and flexural strength performance, and demonstrates enhanced slump flow, viscosity, and passing ability for self-compacting applications.

[0046] The self-compacting concrete composition 100 comprises 17.59 weight percentage of the ordinary Portland cement (OPC) 102, 4.42 weight percentage of the ground granulated blast furnace slag (GGBFS) 104, 0.11 weight percentage of the colloidal nano-silica solids 106, 0.23 weight percentage of the colloidal nano-silica liquid 108, 8.40 weight percentage of the water 110, 33.51 weight percentage of the fine aggregate 112, 35.63 weight percentage of the coarse aggregate 114, and 0.15 weight percentage of the polycarboxylate ether (PCE)-based superplasticizer 116.

[0047] In one embodiment herein, the self-compacting concrete composition 100 comprises 32% of nano-silica solids 106 and 68% of nano-silica liquids 108 and is configured to be added such that its solid fraction is incorporated into the binder phase, and its liquid fraction is added to the mixing water, thereby enabling consistent binder-to-water proportioning and balanced pozzolanic reactivity. In one embodiment herein, the colloidal nano-silica solids 106 are present at an optimum dosage of at least 1.5 weight percentage of total binder content, corresponding to a total colloidal nano-silica input of 7.93 kg/m³.

[0048] In one embodiment herein, the OPC 102, the GGBFS 104, and the colloidal nano-silica solids 106 collectively form a binder phase of the self-compacting concrete composition 100. In one embodiment herein, the water 110 is incorporated in a quantity such that the water-to-binder ratio is maintained at 0.38, thereby optimizing hydration, rheology, and mechanical strength properties. In one embodiment herein, the fine aggregate 112 comprises natural river sand conforming to Zone II gradation, and the coarse aggregate 114 comprises crushed stone with a nominal maximum size of 10 mm. In one embodiment herein, the PCE-based superplasticizer 116 includes a viscosity-modifying admixture, thereby improving steric repulsion, enhancing dispersion of nano-silica particles, and maintaining workability over time.

[0049] The binder phase of the self-compacting concrete composition 100 comprises the ordinary Portland cement (OPC) 102 53 grade, having a specific gravity of 3.13, a standard consistency of 29.50%, and compressive strength values of 49 MPa at 7 days and 60 MPa at 28 days, respectively, thereby providing the primary source of calcium silicate for strength development. In one embodiment herein, a supplementary cementitious material, the ground granulated blast furnace slag (GGBFS) 104, is incorporated as a partial cement replacement with a specific gravity of 2.90, standard consistency of 29%, and compressive strength of 29 MPa at 7 days and 49 MPa at 28 days. The GGBFS is employed at a fixed replacement level of 20% by weight of the total binder to enhance the long-term durability and reactivity profile of the concrete composition 100. The colloidal nano-silica solids 106 and the colloidal nano-silica liquids 108, designated as CemSyn XTX, are used as an advanced pozzolanic additive. The colloidal nano-silica has a specific gravity of 1.22 and is comprised of 32% amorphous nano-silica solids 106 and 68% colloidal nano-silica liquids 108. The nano-silica is added in varying proportions of 0%, 0.5%, 1%, 1.5%, and 2% by weight of the total binder. The colloidal nano-silica solids 106 are measured as part of the binder content, while the colloidal nano-silica liquids 108 are included in the water 110, thereby ensuring accurate maintenance of the water-to-binder ratio.

[0050] In one embodiment herein, the coarse aggregate 114 is crushed granite of nominal maximum size 10 mm with a specific gravity of 2.88. The fine aggregate 112 is selected as natural river sand conforming to Zone II grading with a fineness modulus of 2.66 and a specific gravity of 2.61. This coarse aggregate 114 and the fine aggregate 112 collectively satisfied the gradation and packing density requirements for self-compacting concrete (SCC), with fine aggregate proportion maintained between 48% and 60% of total aggregate mass, thereby ensuring proper particle interaction and fluidity.

[0051] In one embodiment herein, the polycarboxylate ether (PCE)-based superplasticizer 116 with viscosity-modifying admixture (VMA) characteristics is used as the high-range water-reducing admixture. The PCE admixture has a specific gravity of 1.08 and is dosed at 0.5% by weight of binder content for the 0% nano-silica mix (Mi0NS20G) and at 0.7% for all mixes containing colloidal nano-silica to counteract increased surface area and maintain flowability. The VMA functionality supported steric repulsion and homogeneous dispersion of nanoparticles.

[0052] In one embodiment herein, the water 110 is used with precise adjustments made to account for the liquid content of the colloidal nano-silica, maintaining a constant water-to-binder ratio (W/B) of 0.38 across all mixes. The water content is optimized at 201 kg/m³, while the binder content totaled 528.95 kg/m³, thereby yielding a total powder content of 553 kg/m³.

[0053] In one embodiment herein, the self-compacting concrete composition 100 is configured to achieve Grade 30 compressive strength with a mean target strength of 38.25 N/mm², taking into account a standard deviation (S.D.) as per statistical quality control. Entrapped air content is fixed at 1.5% of total concrete volume, given the maximum aggregate size of 10 mm. The total fines content is evaluated to be 24.05 kg/m³, while the percentage of particles passing through a 0.125 mm IS sieve is determined as 3%, thereby confirming acceptable fines distribution for SCC behavior. The total aggregate quantity is determined such that fine aggregate 112 formed an appropriate proportion within the 48–60% range, thereby ensuring cohesive paste-aggregate interaction.

[0054] In one embodiment herein, five trial mixes are prepared and designated as Mi0NS20G (0% nano-silica, 20% GGBFS), Mi0.5NS20G (0.5% nano-silica solids), Mi1NS20G (1% nano-silica solids), Mi1.5NS20G (1.5% nano-silica solids), and Mi2NS20G (2% nano-silica solids). The corresponding nano-silica solids and liquids are measured separately and incorporated into the binder and water phases, respectively. The constituents of each mix are thoroughly blended in a mechanical concrete mixer. First, the binder phase (OPC 102 + GGBFS 104 + nano-silica solids 106) is dry mixed with the fine aggregate 112 and the coarse aggregate 114. Next, a homogenized liquid solution containing the nano-silica liquids 108, the water 110, and the PCE-based superplasticizer 116 is added to the dry mix. Mixing continued for 3 to 5 minutes to obtain a homogeneous and flowable self-compacting concrete composition 100 without segregation. In one embodiment herein, five trial self-compacting concrete (SCC) compositions 100 are prepared to determine the influence of increasing colloidal nano-silica (NS) content at a fixed ground granulated blast furnace slag (GGBFS) replacement level of 20% by binder weight. The mixes are designated as Mi0NS20G, Mi0.5NS20G, Mi1NS20G, Mi1.5NS20G, and Mi2NS20G, representing incremental nano-silica solid dosages of 0%, 0.5%, 1.0%, 1.5%, and 2.0% respectively. In each mix, the nano-silica additive comprises 32% nano-silica solids 106 and 68% nano-silica liquid 108, where the solid fraction is incorporated into the binder phase, and the liquid fraction is considered part of the mixing water to ensure accurate binder-to-water proportioning.

[0055] In the Mi0NS20G mix, the binder phase consists of 423.16 kg/m³ of ordinary Portland cement (OPC) 102 and 105.79 kg/m³ of GGBFS 104, with no nano-silica solids 106 present. In the Mi0.5NS20G mix, the binder comprises 422.31 kg/m³ of OPC 102, 105.79 kg/m³ of GGBFS 104, and 0.85 kg/m³ of nano-silica solids 106. In the Mi1NS20G mix, the binder includes 421.47 kg/m³ of OPC 102, 105.79 kg/m³ of GGBFS 104, and 1.69 kg/m³ of nano-silica solids 106. The Mi1.5NS20G mix consists of 420.62 kg/m³ of OPC 102, 105.79 kg/m³ of GGBFS 104, and 2.54 kg/m³ of nano-silica solids 106. Finally, the Mi2NS20G mix contains 419.77 kg/m³ of OPC 102, 105.79 kg/m³ of GGBFS 104, and 3.39 kg/m³ of nano-silica solids 106. Across all mixes, the GGBFS 104 is incorporated as 20% replacement by weight of total binder to enhance long-term durability and pozzolanic reactivity.

[0056] The colloidal nano-silica liquids 108 are proportionally adjusted in each mix to maintain the 32:68 solid-to-liquid distribution. Accordingly, the nano-silica liquid content is 0 kg/m³ in Mi0NS20G, 1.79 kg/m³ in Mi0.5NS20G, 3.60 kg/m³ in Mi1NS20G, 5.39 kg/m³ in Mi1.5NS20G, and 7.19 kg/m³ in Mi2NS20G. The nano-silica liquids 108 are combined with the mixing water 110, while carefully adjusting the total water to maintain the constant water-binder ratio.

[0057] In all five mixes, the water content 110 is maintained consistently at 201 kg/m³, ensuring a constant water-to-binder ratio (W/B) of 0.38. This precise adjustment enables balanced hydration, effective dispersion of colloidal nano-silica particles, and consistent rheological behavior critical for self-compacting performance. The fine aggregate 112, composed of natural river sand conforming to Zone II grading, is fixed at 801.75 kg/m³ across all mixes to maintain uniform packing density and flowability. The coarse aggregate 114, comprising crushed granite of nominal maximum size 10 mm, is gradually reduced with increasing nano-silica content to accommodate the incremental addition of binder-phase solids and liquids while preserving total mix volume. The coarse aggregate 114 quantities are 871.75 kg/m³ for Mi0NS20G, 863.47 kg/m³ for Mi0.5NS20G, 858.00 kg/m³ for Mi1NS20G, 852.54 kg/m³ for Mi1.5NS20G, and 847.07 kg/m³ for Mi2NS20G.

[0058] The polycarboxylate ether (PCE)-based superplasticizer 116 is incorporated as a high-range water reducer and viscosity-modifying admixture. The dosage is maintained at 2.64 kg/m³ (approximately 0.5% of binder) for Mi0NS20G and increased to 3.70 kg/m³ (approximately 0.7% of binder) for the nano-silica containing mixes Mi0.5NS20G, Mi1NS20G, Mi1.5NS20G, and Mi2NS20G, in order to counterbalance increased surface area from nano-silica addition and maintain target workability. In all embodiments, the calculated total binder content (cement + GGBFS + NS solids) ranges approximately between 528.95 kg/m³ (Mi0NS20G) and 528.95 kg/m³ (Mi2NS20G), indicating controlled binder phase consistency while adjusting individual constituents. The total powder content, considering binder plus fines content of aggregates, remains optimized for the self-compacting application

[0059] The trial mixes are prepared by first dry-mixing the binder constituents (OPC 102, GGBFS 104, and NS solids 106) together with fine aggregate 112 and coarse aggregate 114 for homogenization. Subsequently, a premixed liquid solution containing nano-silica liquids 108, water 110, and PCE-based superplasticizer 116 is gradually added to the dry mixture. Mixing is carried out in a high-shear concrete mixer for 3–5 minutes to ensure uniform dispersion of nano-silica particles, prevent agglomeration, and achieve a homogenous, flowable self-compacting concrete 100. No segregation or bleeding is observed, and all trial batches satisfied required slump flow, T500, viscosity, and passing ability characteristics suitable for SCC placement.

[0060] The self-compacting concrete composition 100 is subjected to the following standard workability tests, which include a slump flow test on the flow table equipment, as shown in FIG. 3, where the spread diameter (in mm) is measured to assess flowability. V-funnel test, as shown in FIG. 5, to determine viscosity by recording the time taken (in seconds) for concrete to flow through a narrow funnel, L-box test, as shown in FIG. 4, to assess passing ability by computing the height ratio (h2/h1) after the concrete flows horizontally through rebar-simulating obstructions.

[0061] In one embodiment herein, the self-compacting concrete composition 100 is formulated to meet the requirements of grade 30 self-compacting concrete and achieves a target compressive strength of at least 38.25 N/mm² at 28 days. In one embodiment herein, the self-compacting concrete composition 100 demonstrates at least a 10% increase in compressive strength at 7 days and at least a 15% increase at 91 days, relative to a reference SCC mix without nano-silica. In one embodiment herein, the self-compacting concrete composition 100 exhibits at least 20% improvement in split tensile strength and at least 10% improvement in flexural strength at 28 days, thereby enhancing ductility and crack resistance in structural members. In one embodiment herein, the self-compacting concrete composition 100 exhibits a slump flow of at least 730 mm, a V-funnel flow time below 10 seconds, and a passing ability (L-box ratio) of 1.00. In one embodiment herein, the workability test values of the self-compacting concrete composition 100 are shown in Table 2.

[0062] Table 2:
Mix
Notation Slump
(mm) h1
(mm) h2
(mm) Passing Ability (h1/
h2) Viscosity
(S)
Mi ONS 20G 650 5 8 0.63 11
Mi 0.5 NS20G 720 6.5 8.3 0.78 8
Mi 1NS 20G 720 7 6 0.88 8
Mi 1.5NS20G 730 7.2 7.2 1.00 8
Mi 2NS 20G 690 7 8 0.88 8

[0063] According to an exemplary embodiment of the invention, FIG. 2 refers to a screenshot 200 depicting a flow table equipment evaluating slump flow behavior of the self-compacting concrete composition 100. The test setup comprises a standard slump cone placed centrally on a rigid, metallic flow table platform. The cone is filled with freshly prepared concrete composed of the OPC 102, the GGBFS 104, the colloidal nano-silica solids 106, the colloidal nano-silica liquids 108, the fine aggregate 112, the coarse aggregate 114, the PCE-based superplasticizer 116, and the water 110 mixed according to the design proportions. After the cone is removed vertically, the table is dropped vertically in controlled jolts to simulate a vibration-free compaction scenario. The slump flow is measured as the average diameter (in mm) of the concrete spread in two perpendicular directions. The optimal mix, Mi1.5NS20G, incorporating 1.5% colloidal nano-silica solids 106 and colloidal nano-silica liquids 108, demonstrated a maximum slump flow of 730 mm, indicating superior deformability, flowability, and resistance to segregation. The result confirms that nano-silica, through pozzolanic interaction and particle packing, significantly improves the self-levelling properties of SCC.

[0064] According to an exemplary embodiment of the invention, FIG. 3 refers to a screenshot 300 depicting a slump flow measurement of the self-compacting concrete composition 100. The screenshot 300 captures the horizontal spread of the concrete after the slump cone was lifted and the table jolted. The test visually confirms the flow profile and circularity of the concrete, validating its ability to flow under its own weight without vibration. As per the experimental data, the slump flow values ranged from 650 mm to 730 mm, with the maximum achieved at 1.5% nano-silica solids 106. A decrease in flowability is observed at 2% nano-silica, where the slump reduced to 690 mm, indicating a threshold beyond which excess nano-silica may agglomerate and reduce free water availability. The self-compacting concrete composition 100 ensured the water-to-binder ratio (W/B) of 0.38 and the PCE-based superplasticizer 116 dosage of 0.7% for nano-silica mixes to maintain fluidity. The screenshot 300 and corresponding results confirm that the self-compacting concrete composition 100 achieves optimal flowability through precise tuning of binder phase, nano-silica dosage, and admixture compatibility.

[0065] According to an exemplary embodiment of the invention, FIG. 4 refers to a screenshot 400 depicting a passing ability test of the self-compacting concrete composition 100. The L-box setup consists of a vertical leg filled with freshly mixed SCC and a horizontal leg simulating reinforcement congestion through steel bars. Once the gate is lifted, concrete flows from the vertical to the horizontal section, and the passing ability ratio is determined as h2/h1, where h2 is the height of concrete in the horizontal portion and h1 in the vertical portion. The optimized mix Mi1.5NS20G achieved a perfect passing ratio of 1.00, as required by EFNARC standards for high-performance SCC. This demonstrates the mix’s ability to flow through narrow spaces without blocking or aggregate segregation. In contrast, lower ratios are observed in other mixes, 0.63 for Mi0NS20G, 0.78 for Mi0.5NS20G, and 0.88 for Mi1NS20G, indicating restricted flow due to less cohesive paste structure. The role of colloidal nano-silica solids and the colloidal nano-silica liquids (106, 108) in improving the particle dispersion and reducing inter-particle friction is validated through this result.

[0066] According to an exemplary embodiment of the invention, FIG. 5 refers to a screenshot 500 depicting a viscosity test of the self-compacting concrete composition 100. The V-funnel comprises a narrow, V-shaped container through which the SCC flows under gravity when the bottom gate is opened. The flow time in seconds is recorded to quantify viscosity and assess the concrete’s resistance to flow due to internal cohesion and matrix friction. For the optimal mix Mi1.5NS20G, the recorded flow time is 8 seconds, indicating ideal viscosity suitable for SCC applications. Other recorded values are 11 seconds (Mi0NS20G), 8 seconds (Mi0.5NS20G), and 8 seconds (Mi1NS20G). The results demonstrate that the addition of the colloidal nano-silica solids 106 and the colloidal nano-silica liquids 108 improves the mix's cohesiveness without causing blockage or excessive flow resistance, due to its high surface reactivity and interaction with liberated calcium hydroxide. The flow time remained below the EFNARC-specified limit of 10 seconds, thereby affirming that the self-compacting concrete composition 100 provides an ideal balance between viscosity and flowability.

[0067] According to an exemplary embodiment of the invention, FIG. 6 refers to a graph 600 depicting a variation of compressive strength of the self-compacting concrete composition 100 at 7, 28, and 91 days. The graph 600 compares five concrete mixes, including the reference mix Mi0NS20G (containing 0% colloidal nano-silica solids) and four modified mixes incorporating colloidal nano-silica solids 106 in varying proportions, with corresponding liquid fractions of the colloidal nano-silica liquids 108 adjusted in the water 110 to maintain the constant water-to-binder ratio of 0.38.

[0068] At 7 days, the compressive strength of the mix Mi0.5NS20G increased by 2.71%, Mi1NS20G by 4.96%, and the optimized mix Mi1.5NS20G by 11.71% compared to the reference mix Mi0NS20G. However, the strength of Mi2NS20G, which contains 2% colloidal nano-silica solids 106, showed a reduction of 8.12%, indicating overdosage beyond optimal pozzolanic saturation. At 28 days, the compressive strength trend remained consistent. The mixes Mi0.5NS20G, Mi1NS20G, Mi1.5NS20G, and Mi2NS20G exhibited strength enhancements of 1.43%, 4.01%, 8.58%, and 5.99%, respectively, over the reference. The results confirm the role of the colloidal nano-silica solids 106 and the colloidal nano-silica liquids 108 in promoting early and continued hydration, densifying the cementitious matrix through the formation of additional calcium silicate hydrate (C-S-H) gel.

[0069] At 91 days, the long-term strength development further highlighted the effectiveness of the 1.5% nano-silica dosage. While Mi0.5NS20G and Mi2NS20G experienced minor reductions in strength of 0.82% and 1.10%, respectively, relative to the reference, the mixes Mi1NS20G and Mi1.5NS20G demonstrated significant gains of 3.05% and 17.45%, respectively. This reflects the sustained pozzolanic reactivity of nano-silica, which continuously consumes calcium hydroxide liberated during hydration and produces additional C-S-H gel, leading to microstructural densification.

[0070] The marked increase in compressive strength, especially for the optimized Mi1.5NS20G mix, is attributed to the fine particle size and high surface area of colloidal nano-silica, which accelerates the hydration kinetics and fills micro voids within the cement matrix. The nano-silica acts as a nucleation site, facilitating the conversion of portlandite to secondary C-S-H, thus improving both early-age and long-term strength characteristics of the self-compacting concrete composition 100.

[0071] According to an exemplary embodiment of the invention, FIG. 7 refers to a graph 700 depicting a variation of split tensile strength of the self-compacting concrete composition 100 at 7, 28, and 91 days. The test results compare a reference mix (Mi0NS20G) with four SCC mixes containing varying dosages of the colloidal nano-silica solids 106 and the colloidal nano-silica liquids 108. At 7 days, the addition of colloidal nano-silica led to substantial increases in split tensile strength. Specifically, the mix Mi0.5NS20G showed an enhancement of 22.17%, Mi1NS20G increased by 32.55%, the optimized mix Mi1.5NS20G recorded a maximum gain of 43.40%, and Mi2NS20G showed a rise of 20.28% compared to the reference mix Mi0NS20G. These early-age improvements can be attributed to the rapid pozzolanic reaction of nano-silica with calcium hydroxide (CH) produced during primary cement hydration. The nano-silica particles accelerate the formation of calcium silicate hydrate (C-S-H) gel, which densifies the microstructure and enhances tensile resistance.

[0072] At 28 days, the gains in split tensile strength remained consistently high. Mi0.5NS20G, Mi1NS20G, Mi1.5NS20G, and Mi2NS20G exhibited strength improvements of 12.50%, 21.59%, 23.11%, and 10.61%, respectively, over the reference. This indicates that the long-term hydration and filler effects of nano-silica continued to refine the interfacial transition zone (ITZ) between the aggregate and paste, thereby reducing microcracks and increasing tensile load-bearing capacity.

[0073] At 91 days, long-term durability effects are observed. Mixes Mi0.5NS20G, Mi1NS20G, and Mi1.5NS20G demonstrated sustained improvements of 3.17%, 4.61%, and 9.51%, respectively, over the reference. However, the mix Mi2NS20G, which contained 2% nano-silica solids, showed a reduction of 1.44% compared to the reference. This decrease is likely due to an overdosage of nanoparticles beyond the optimal threshold, which may cause dilution of the cementitious matrix and interfere with the efficient development of C-S-H gel. The observed trend confirms that 1.5% colloidal nano-silica solids 106 represents the optimal dosage for achieving the maximum enhancement in split tensile strength. The improvement is attributed to several factors, such as the ultra-fine nano-silica particles acting as nucleation sites for C-S-H formation, the ultra-fine nano-silica particles filling micro voids, leading to a denser matrix, and the ultra-fine nano-silica particles improving the bond between aggregate and paste. However, at higher dosages, such as 2%, excess nanoparticles may agglomerate or act inertly, resulting in localized defects or weak zones due to incomplete dispersion and inadequate water availability for continued hydration. Thus, the self-compacting concrete composition 100 with the OPC 102, the GGBFS 104, the colloidal nano-silica solids 106, and the PCE-based superplasticizer 116 achieves significantly enhanced split tensile strength at early and later curing ages, particularly with an optimized nano-silica dosage of 1.5%.

[0074] According to an exemplary embodiment of the invention, FIG. 8 refers to a graph 800 depicting a variation of flexural strength of the self-compacting concrete composition 100 at 7, 28, and 91 days. The test results represent the flexural behavior of five concrete mix variants, including a reference mix (Mi0NS20G) without nano-silica and four modified mixes incorporating varying dosages of colloidal nano-silica solids 106 and the corresponding colloidal nano-silica liquids 108, adjusted in the water 110. At 7 days, significant improvement in flexural strength is observed with increasing nano-silica content up to an optimal dosage. The mix Mi0.5NS20G recorded a 12.41% increase in strength, Mi1NS20G showed an increase of 18.73%, and the optimized mix Mi1.5NS20G exhibited the highest gain of 26.28% compared to the reference mix Mi0NS20G. However, Mi2NS20G, which incorporated 2% colloidal nano-silica solids 106, exhibited a reduction of 4.14% in flexural strength at 7 days. These findings suggest that nano-silica enhances early-age flexural performance by refining the cement matrix and improving crack-bridging capabilities through densification of the interfacial transition zone (ITZ). At 28 days, the trend continued with all nano-silica mixes outperforming the reference. The mix Mi0.5NS20G increased by 3.88%, Mi1NS20G by 8.99%, Mi1.5NS20G by 15.17%, and Mi2NS20G by 12.52% relative to the reference. The continued strength development is attributed to the sustained pozzolanic activity of nano-silica, which reacts with liberated calcium hydroxide to generate additional calcium silicate hydrate (C-S-H) gel, thereby leading to a more cohesive and durable matrix.

[0075] At 91 days, all nano-silica-containing mixes maintained or exceeded the performance of the reference mix. Mi0.5NS20G, Mi1NS20G, Mi1.5NS20G, and Mi2NS20G recorded flexural strength improvements of 5.64%, 5.97%, 6.29%, and 5.00%, respectively, over the reference. The long-term results confirm that even at lower dosages, colloidal nano-silica effectively contributes to microstructural refinement and durability, while the 1.5% dosage remained optimal for maximizing flexural resistance. The enhancement in flexural strength across curing ages is primarily due to the high pozzolanic reactivity and nano-filler effects of colloidal nano-silica, which accelerates the consumption of calcium hydroxide during early hydration, producing dense C-S-H gel that bridges microcracks and reinforces the tensile zone under flexural loads. Additionally, the steric dispersion effect imparted by the PCE-based superplasticizer 116 prevents particle agglomeration, thereby ensuring even nano-silica distribution throughout the matrix. These results confirm that the inclusion of 1.5% colloidal nano-silica solids 106 in the self-compacting concrete composition 100 provides the most effective balance between strength enhancement and mix workability. The resulting improvement in flexural capacity enhances the ductility and crack resistance of structural elements.

[0076] According to an exemplary embodiment of the invention, FIG. 9 refers to a flowchart 900 of a method for preparing the self-compacting concrete composition 100. At step 902, the ordinary Portland cement (OPC) 102, the ground granulated blast furnace slag (GGBFS) 104, and the colloidal nano-silica solids 106 having 32% active nano solids are weighed and mixed to form a binder mixture. At step 904, the fine aggregate 112, which includes natural river sand conforming to Zone II grading, and the coarse aggregate 114, which includes crushed stone with the nominal maximum size of at least 10 mm, are weighed and prepared, and then the prepared fine aggregate 112 and the coarse aggregate 114 are added to the binder mixture.

[0077] At step 906, 68% of colloidal nano-silica liquids 108 are measured and mixed with the water 110 to obtain a water mixture, and the total water content is adjusted to maintain a water-to-binder ratio of at least 0.38. At step 908, the polycarboxylate ether (PCE)-based superplasticizer 116 with viscosity-modifying properties is measured and mixed into the water mixture to form a homogenized liquid solution. At step 910, the binder mixture, the fine aggregate 112, and the coarse aggregate 114 are mixed in a mechanical concrete mixer for a predetermined time period to ensure uniform distribution, thereby obtaining a dry mixture.

[0078] At step 912, the homogenized liquid solution is added into the dry mixture under continuous mixing in the mechanical concrete mixer for a predetermined time period to form the self-compacting concrete composition 100. At step 914, the prepared self-compacting concrete composition 100 is discharged into formwork without vibration, thereby allowing it to self-level and fill the mold through gravitational flow and internal cohesion. Further, at step 916, the self-compacting concrete composition 100 is cured under standard moist curing conditions at a predetermined temperature and relative humidity for at least 7 to 91 days, thereby achieving the slump flow of at least 730 mm, the passing ability ratio of 1.00, the viscosity of 8 seconds, and enhanced compressive strength, split tensile strength, and flexural strength compared to a reference self-compacting concrete lacking colloidal nano-silica.

[0079] Numerous advantages of the present disclosure may be apparent from the discussion above. In accordance with the present disclosure, a self-compacting concrete composition 100 that exhibits enhanced slump flow, compressive strength, split tensile strength, and flexural strength, facilitating high flowability and durability in construction applications, is disclosed. The proposed self-compacting concrete composition 100 integrates the ordinary Portland cement 102, the ground-granulated blast-furnace slag 104, and colloidal nano-silica solids 106, added with the colloidal nano-silica liquids 108 to form a balanced grade-30 binder system. The self-compacting concrete composition 100 achieves the slump-flow diameter of at least 650 mm, thereby enabling placement without mechanical vibration even in heavily reinforced sections. The self-compacting concrete composition 100 delivers a minimum 8 % increase in 28-day compressive strength over a reference SCC mix containing no nano-silica. The self-compacting concrete composition 100 exhibits enhanced split-tensile and flexural strengths, thereby improving crack resistance and overall structural performance.

[0080] The self-compacting concrete composition 100 reduces the ordinary Portland cement 102 usage by 20 % through the GGBFS 104 substitution, thereby lowering embodied CO₂ and supporting sustainable construction practices. The self-compacting concrete composition 100 densifies the micro-structure, decreases permeability, and extends durability against aggressive environments. The self-compacting concrete composition 100 consistently satisfies flowability, viscosity, and passing-ability criteria, streamlining production for precast, ready-mix, and in-situ applications. The self-compacting concrete composition 100 offers a cost-effective, high-performance, and industrially scalable solution, fostering faster construction cycles and longer service life of civil structures.

[0081] In one embodiment herein, the workability performance of the self-compacting concrete composition 100 is found to be optimum at the colloidal nano-silica (NS) solids 106 dosage of 1.5% by weight of total binder content. At this dosage, the self-compacting concrete composition 100 achieved the slump flow of 730 mm, confirming excellent flowability and self-compacting characteristics. However, beyond 1.5% NS solids, a noticeable decrease in the slump flow is observed, attributable to the excessive water demand caused by the increased surface area and absorptive capacity of nano-silica particles. As a result, an additional dosage of the PCE-based superplasticizer 116, exceeding 0.7% by binder weight, became necessary to maintain adequate flow and prevent loss of workability.

[0082] In one embodiment herein, the compressive strength of the optimized SCC mix (Mi1.5NS20G) demonstrated substantial improvement over the reference mix (Mi0NS20G) at all curing ages. Specifically, compressive strength increased by 11.71% at 7 days, 8.58% at 28 days, and 17.45% at 91 days. This enhancement is primarily attributed to the accelerated pozzolanic reaction of colloidal nano-silica with the calcium hydroxide (CH) released during cement hydration, resulting in the formation of additional calcium silicate hydrate (C-S-H) gel. This secondary C-S-H gel densifies the cement matrix and improves mechanical interlock between binder and aggregates.

[0083] In one embodiment herein, the split tensile strength of the self-compacting concrete composition 100 also increased significantly with nano-silica addition, reaching its maximum performance at the 1.5% NS dosage. The observed increase in tensile strength is 43.40% at 7 days, 23.11% at 28 days, and 9.51% at 91 days over the reference mix. The performance enhancement is a result of rapid CH consumption in early hydration stages and microstructural densification due to nano-silica’s high surface reactivity. However, exceeding the optimal nano-silica dosage (i.e., 2%) led to marginal reductions in strength due to unreacted silica accumulation, formation of weak zones, and possible particle agglomeration from poor dispersion, thereby reducing bonding efficiency in the matrix.

[0084] In one embodiment herein, the flexural strength of the SCC composition 100 followed a similar trend, with optimal improvement observed at 1.5% NS solids dosage. The flexural strength gains are 26.28% at 7 days, 15.17% at 28 days, and 6.29% at 91 days. The strength enhancement stems from the early formation of a dense, cohesive cement matrix through accelerated CH consumption and nucleation of C-S-H gel around nano-silica particles, which helps resist tensile cracking and improves ductility under bending loads. In one embodiment herein, the inclusion of colloidal nano-silica solids and the colloidal nano-silica liquids (106, 108) in the SCC mix provided additional advantages due to its extremely fine particle size and high specific surface area. This allowed nano-silica to act as a chemical binder bridge between cement particles and aggregate interfaces, thereby enhancing matrix continuity. As a result, the initial and final setting times are reduced, and early-age strength development is accelerated, thereby enabling faster formwork removal and earlier load-bearing capability.

[0085] It will readily be apparent that numerous modifications and alterations can be made to the processes described in the foregoing examples without departing from the principles underlying the invention, and all such modifications and alterations are intended to be embraced by this application. , Claims:CLAIMS:
I/We Claim:
1. A self-compacting concrete composition (100) with improved mechanical strength properties, comprising:
15 to 20 weight percentage of ordinary Portland cement (OPC) (102);
4 to 6 weight percentage of ground granulated blast furnace slag (GGBFS) (104);
0.1 to 0.2 weight percentage of colloidal nano-silica solids (106);
0.2 to 0.3 weight percentage of colloidal nano-silica liquid (108);
7.5 to 9.5 weight percentage of water (110);
32 to 36 weight percentage of fine aggregate (112);
34 to 38 weight percentage of coarse aggregate (114); and
0.1 to 0.2 weight percentage of polycarboxylate ether (PCE)-based superplasticizer (116),
whereby the self-compacting concrete composition (100), when mixed and cured, exhibits superior compressive, split tensile, and flexural strength performance and demonstrates enhanced slump flow, viscosity, and passing ability for self-compacting applications.
2. The self-compacting concrete composition (100) as claimed in claim 1, wherein the OPC (102), the GGBFS (104), and the colloidal nano-silica solids (106) collectively form a binder phase of the self-compacting concrete composition (100).
3. The self-compacting concrete composition (100) as claimed in claim 1, wherein the self-compacting concrete composition (100) is formulated to meet the requirements of grade 30 self-compacting concrete and achieves a target compressive strength of at least 38.25 N/mm² at 28 days.
4. The self-compacting concrete composition (100) as claimed in claim 1, wherein the water (110) is incorporated in a quantity such that the water-to-binder ratio is maintained at 0.38, thereby optimizing hydration, rheology, and mechanical strength properties.
5. The self-compacting concrete composition (100) as claimed in claim 1, wherein the self-compacting concrete composition (100) comprises 32% of nano-silica solids (106) and 68% of nano-silica liquids (108) and is configured to be added such that its solid fraction is incorporated into the binder phase and its liquid fraction is added to the mixing water, thereby enabling consistent binder-to-water proportioning and balanced pozzolanic reactivity.
6. The self-compacting concrete composition (100) as claimed in claim 1, wherein the colloidal nano-silica solids (106) are present at an optimum dosage of at least 1.5 weight percentage of total binder content, corresponding to a total colloidal nano-silica input of 7.93 kg/m³.
7. The self-compacting concrete composition (100) as claimed in claim 1,
wherein the fine aggregate (112) comprises natural river sand conforming to Zone II gradation, and the coarse aggregate (114) comprises crushed stone with a nominal maximum size of 10 mm,
wherein the PCE-based superplasticizer (116) includes a viscosity-modifying admixture, thereby improving steric repulsion, enhancing dispersion of nano-silica particles, and maintaining workability over time.
8. The self-compacting concrete composition (100) as claimed in claim 1,
wherein the self-compacting concrete composition (100) demonstrates at least 10% increase in compressive strength at 7 days and at least 15% increase at 91 days, relative to to a reference self-compacting concrete mix without nano-silica,
wherein the self-compacting concrete composition (100) exhibits at least 20% improvement in split tensile strength and at least 10% improvement in flexural strength at 28 days, thereby enhancing ductility and crack resistance in structural members,
wherein the self-compacting concrete composition (100) exhibits a slump flow of at least 730 mm, a V-funnel flow time below 10 seconds, and a passing ability (L-box ratio) of 1.00.
9. A method for preparing a self-compacting concrete composition (100), comprising:
weighing and mixing ordinary Portland cement (OPC) (102), ground granulated blast furnace slag (GGBFS) (104), and colloidal nano-silica solids (106) having 32% active nano solids to form a binder mixture;
weighing and preparing fine aggregate (112), which includes natural river sand conforming to Zone II grading, and coarse aggregate (114), which includes crushed stone with a nominal maximum size of at least 10 mm, and adding the fine aggregate (112) and the coarse aggregate (114) to the binder mixture;
measuring and mixing 68% of colloidal nano-silica liquids (108) with water (110) to obtain a water mixture and adjusting the total water content to maintain a water-to-binder ratio of at least 0.38;
measuring a polycarboxylate ether (PCE)-based superplasticizer (116) with viscosity-modifying properties, and mixing it into the water mixture to form a homogenized liquid solution;
mixing the binder mixture, the fine aggregate (112), and the coarse aggregate (114) in a mechanical concrete mixer for a predetermined time period to ensure uniform distribution, thereby obtaining a dry mixture;
adding the homogenized liquid solution into the dry mixture under continuous mixing in the mechanical concrete mixer for a predetermined time period to form the self-compacting concrete composition (100);
discharging the prepared self-compacting concrete composition (100) into formwork without vibration, thereby allowing it to self-level and fill the mold through gravitational flow and internal cohesion; and
curing the self-compacting concrete composition (100) under standard moist curing conditions at a predetermined temperature and relative humidity for at least 7 to 91 days, thereby achieving a slump flow of at least 730 mm, a passing ability ratio of 1.00, a viscosity of 8 seconds, and enhanced compressive strength, split tensile strength, and flexural strength compared to a reference self-compacting concrete lacking colloidal nano-silica.