Performance evaluation of self-compacting concrete incorporating sunflower husk ash as a sustainable cement substitute.

This study examines the potential of high-volume Supplementary Cementitious Materials (SCMs) in advancing sustainable, low-cost, low-carbon Self-Compacting Concrete (SCC) through a quaternary binder design. Ground Granulated Blast Furnace Slag (GGBFS), Class F Fly Ash (FA), and Silica Fume (SF) were incorporated as partial replacements for Ordinary Portland Cement (OPC) to formulate Quaternary Blended Self-Compacting Concrete (QBSCC). Twenty-eight mixes were developed, including one control and twenty-seven quaternary blends, at a constant water-to-binder ratio of 0.4. The SCMs substitution ranged from 42.5% to 77.5%, with GGBFS serving as the dominant component. Rheological compatibility of the quaternary binder composition and superplasticizer dosage was assessed using mini-slump and Marsh cone tests. Fresh-state properties of QBSCC were evaluated through slump flow, L-box, V-funnel, and J-ring tests. Mechanical performance was characterized by compressive, split tensile, and flexural strength tests, and durability was assessed using Rapid Chloride Permeability and electrical resistivity methods. Economic and environmental impacts were quantified via cost analysis and carbon footprint assessment. The results demonstrate that all QBSCC mixtures exhibited superior flowability compared to the reference mix. Compressive strength improved modestly (1– 4%) at 28 days for mixes with 42.5–50% SCMs replacement and more substantially (up to 7%) at 56 days for 42.5–57.5% replacements. Enhancements in tensile and flexural strength followed similar trends. Durability was significantly improved, evidenced by reduced chloride permeability and elevated resistivity. Additionally, QBSCC achieved cost savings of 18– 43% and carbon emission reductions of 38–70%. These outcomes highlight the efficacy of quaternary SCMs systems in producing high-performance, low-carbon SCC with demonstrable technical, economic, and environmental advantages.

Assessment of fresh and hardened properties of concrete using supplementary cementitious materials

SCC (Self compacting concrete) can fill formwork and encloses reinforcing bars under gravity and maintains homogeneity without vibration. SCC shortens the period of construction, guarantees compaction in confined zones, moreover terminates noise due to vibration. The wide spread application of SCC is restricted because of the high cost for the production of SCC with high cement content and chemical admixtures. In order to make the production of SCC economical, and to reduce the high cement content the Ordinary Portland Cement in SCC can be blended with pozzolanic materials like rice husk ash and supplementary cementitious materials like fly ash. In this paper the fresh state properties and mechanical properties such as compressive strength, split tensile strength and flexural strength of SCC with ternary blends of rice husk ash (RHA) and fly ash (FA) were studied. For this purpose, different mixes were prepared by replacing Ordinary Portland Cement (OPC) with 5%, 10%, 15% and 20% of rice husk ash (RHA) and the percentage of addition of fly ash (FA) is fixed as 15% for all these mixes. It was observed that the specimen incorporating 10% of rice husk ash (RHA) and 15% of fly ash (FA) as ternary blend exhibits better mechanical properties such as: Compressive, split tensile and flexural strengths at 28 days of age as compared to traditional mix of SCC without RHA (Rice Husk Ash) and FA (Fly Ash). This research demonstrates that the ideal percentage for a mixture of rice husk ash (RHA) and fly ash as ternary blend is 10% and 15% respectively.

Performance studies on quaternary blended Geopolymer concrete

Evaluation of rheological and durability characteristics of sugarcane bagasse ash and rice husk ash based binary and ternary cementitious system

Self-Compacting Concrete (SCC) is an advanced concrete technology capable of flowing and consolidating under its own weight without mechanical vibration, making it suitable for heavily reinforced and complex structural elements. This study presents an experimental investigation on the fresh, hardened, and non-destructive properties of High-Strength Self-Compacting Concrete (HSSCC) of grade M60 incorporating fly ash and silica fume as supplementary cementitious materials. Ordinary Portland Cement (OPC) 43 grade was partially replaced with fly ash at 0%, 10%, 15%, 20%, and 25%, while silica fume content was kept constant at 8%. A polycarboxylic ether-based superplasticizer was used to achieve the required workability, and mix design was carried out as per IS 10262:2019 and IS 456:2000. Fresh properties were evaluated using slump flow, V-funnel, and L-box tests, while hardened properties were assessed through compressive, split tensile, and flexural strength tests at 7 and 28 days. Ultrasonic Pulse Velocity (UPV) testing was conducted to evaluate internal quality. Results indicated that increasing fly ash content enhanced the workability and flowability of SCC without compromising stability. The mix with 25% fly ash achieved the highest performance, with 28-day compressive strength exceeding 70 MPa and improved tensile and flexural strengths. UPV results confirmed better density and homogeneity. The study concludes that the combined use of fly ash and silica fume is effective in producing sustainable and high-strength SCC suitable for structural applications.

Sustainable concrete for rigid pavement construction using de-hydroxylated Kaolinitic clay: Mechanical and microstructural properties

The environmental impact of concrete production, mainly due to cement manufacturing, has prompted the search for sustainable alternatives, such as agricultural byproducts. Rice husk ash (RHA) and coffee husk ash (CHA) show promise as supplementary cementitious materials that can enhance concrete’s strength and durability. However, RHA’s fine particles reduce workability, and CHA’s lower silica content limits its pozzolanic reactivity. While both have individual benefits, their combined effects on concrete properties remain underexplored. This study investigates the influence of RHA and CHA as partial cement replacements on the fresh and hardened properties of concrete. A C‐25 mix was designed using the ACI 211.1 method, with RHA and CHA proportions ranging from 0% to 25% and 0% to 15%, respectively, in 5% increments. Workability was assessed using slump tests, and mechanical properties—including compressive, split tensile, and flexural strengths—as well as durability (measured through water absorption, strength, and weight loss under 5% sulfuric acid exposure) were evaluated. The results show that both RHA and CHA significantly affect workability, strength, and durability. RHA reduced workability more than CHA due to its finer particles and higher water absorption. The optimal mix of 10% RHA and 5% CHA improved compressive strength by 5.04% and 7.87% at 28 and 56 days, respectively, and enhanced flextural and split tensile strengths by 11.45% and 7.41%, respectively. Durability tests showed that the combination of 15% RHA and 5% CHA (R15C5) significantly reduced water absorption and improved sulfuric acid resistance, indicating a denser microstructure and greater environmental resilience. SEM analysis shows that adding RHA and CHA enhances concrete’s microstructure. The R10C5 mix (10% RHA and 5% CHA) strikes a good balance of strength and refinement. While R15C5 (15% RHA and 5% CHA) improves durability, it shows similar strength and durability to R10C5 due to dilution and higher water demand, as confirmed by statistical analysis. These findings demonstrate that the synergistic use of RHA and CHA can optimize concrete performance, providing a sustainable alternative for enhancing both strength and durability. However, excessive use of RHA or CHA beyond the optimal proportions can compromise performance due to interference with hydration and workability.

Self-compacting concrete represents a unique type of concrete that achieves self-compression through its mass, eliminating the need for external vibrations. The mechanical characteristics of self-compacting concrete can be enhanced by incorporating agricultural waste materials as partial substitutes for cement. In this experimental study, a graded M30 concrete mix was employed to produce self-compacting concrete by replacing cement with 6, 8, 10, 12, and 14% of sugarcane bagasse ash and rice husk ash. To assess the concrete's properties, both in its fresh and hardened states, several tests were conducted. Fresh properties were evaluated using l-box, slump flow, and U-box tests. The results indicated that sugarcane bagasse ash outperformed rice husk ash in enhancing the fresh properties of concrete up to a certain level of replacement. Hardened properties, including split tensile strength, compressive strength, and flexural strength, were tested at both 7-day and 28-day intervals. These tests revealed that rice husk ash exhibited superior performance in enhancing the hardened properties compared to sugarcane bagasse ash. In conclusion, this study underscores the suitability of both sugarcane bagasse ash and rice husk ash as viable options for partial cement replacement in self-compacting concrete, with each material exhibiting strengths in improving certain aspects of fresh and hardened concrete properties.

The durability of concrete requires a dense microstructure which can be achieved by using self-compacting concrete (SCC). Both calcined clay (CC) and rice husk ash (RHA) are promising supplementary cementitious materials (SCMs) that can partially replace cement, but their use in SCC is critical due to their higher water demand (WD) and specific surface area (SSA) compared to cement. The effect of partial substitution of cement at 20 vol-% with binary and ternary blends of CC and RHA on flowability retention and durability of SCC was investigated. The empirical method of SCC design was adopted considering the physical properties of both CC and RHA. The deformability of the SCC was evaluated using the slump flow and J-ring tests. The T500 time and the V-funnel test were used to assess the viscosity of the SCC. The flowability retention was monitored by the plunger method, and flow resistance was determined based on the rheological measurements of SCC. The evolution of the hydrate phases of the binder in SCC was determined by thermogravimetric analysis, while the durability was evaluated by a rapid chloride migration test. Cement partial replacement with 20 vol-% CC has no significant effect on fresh SCC, flowability retention, compressive strength and durability properties. On the other hand, 20 vol-% RHA requires a higher dosage of SP to achieve self-compactability and increase the viscosity of SCC. Its flowability retention is only up to 30 min after mixing and exhibited higher flow resistance. It consumes more calcium hydroxide (CH) and improves the compressive strength and chloride resistance of SCC. The ternary blending with CC and RHA yielded better fresh SCC properties compared to the binary blend with RHA, while an improved chloride penetration resistance could be achieved compared to the binary CC blend.

Strength, permeability and microstructure of self-compacting concrete containing rice husk ash

Supplementary cementitious materials (SCM) have turned out to be a vital portion of extraordinary strength and performance concrete. Metakaolin (MK) is one of SCM material is acquired by calcinations of kaolinite. Universally utilised as pozzolanic material in concrete to enhance mechanical and durability properties. This study investigates the fresh and hardened properties of conventional concrete (CC) and self compacting concrete (SCC) by partially replacing cement with MK in diverse percentages. In CC and SCC, partial replacement of cement with MK varies from 5-20%. Fresh concrete properties of CC are conducted by slump test and compaction factor tests and for SCC, slump flow, T500, J-Ring, L-Box, V-Funnel and U-Box tests. Hardened concrete characteristics are investigated by compressive, split tensile and flexural strengths at age of 7, 28 and 90 days of curing under water. Carbonation depth, water absorption and density of MK based CC and SCC was also computed. Fresh concrete test results indicated that increase in MK replacement increases workability of concrete in a constant w/b ratio. Also outcomes reveal that concrete integrating MK had greater compressive, flexural and split tensile strengths. Optimum replacement level of MK for cement was 10%, which increased mechanical properties and robustness properties of concrete.

Rapid urbanization emanates from increased cement production, resulting in a significant increase in greenhouse gas emissions and pressure on natural resources. Considering these repercussions, it is critical to explore alternative methods to mitigate cement production by carefully examining sustainable solutions derived from nature. This study provides an in-depth investigation into the performance attributes related to compressive strength when cement mortar is formulated using Rice Husk Ash (RHA) and Sugarcane Bagasse Ash (SCBA) as supplementary cementitious materials. The experimental approach of this study comprises a comparative measurement of the workability and compressive strength of mortar produced by incorporating RHA and SCBA under standard and elevated temperature conditions, specifically at 400 °C, 600 °C, and 800 °C. The use of RHA and SCBA had a significant impact on mortar workability, showing a trend in which an increasing amount of cement substitution led to a decrease in workability. Furthermore, the mechanical performance decreased when up to 10% of the cement was replaced with a blend of RHA and SCBA equally divided by 5%. However, a further increase in the RHA-SCBA percentage corresponded to a decrease in the compressive strength. Upon subjecting both the control and RHA-SCBA cement mortar samples to higher temperatures, an anticipated reduction in the strength was observed. However, the samples containing RHA-SCBA demonstrated strength behavior similar to that of the control specimens when exposed to elevated temperature conditions. Based on the findings of this study, both RHA and SCBA are proposed to have the potential to serve as viable replacement materials for the production of cement mortar.

It is critical to improve the strength parameters of recycled coarse aggregate concrete to be equal to virgin aggregate concrete. Thus, the research focusses on using different percentages of replacements of ordinary Portland cement with a supplementary cementitious materials (SCMs) to determine the best combination for structural purposes by adding a hybrid of glass and steel fibres. In the experimentation, the recycled coarse aggregate was used at a constant percentage of 75% as a partial substitute of natural coarse aggregate, and SCMs used as a partial substitute of ordinary Portland cement were rice husk ash at 10, 15, and 20% and also silica fume at 8, 12, and 16% by weight of cement. The hybrid of a glass of steel fibres was also added by volume fraction of concrete in ratios of 50:50, 25:75, and 75:25 in all of the percentage replacements of rice husk ash and silica fume. Mechanical parameters like compressive, flexural, and split tensile strength were assessed. Result revealed that the target strength of M25 was achieved with the combinations of RCA75-RHA15-GF0.5-XSF0.5 (i.e.75% recycled coarse aggregate, 15% cement replacement with rice husk ash, 0.5% glass fibre, and 0.5% steel fibre) and RCA75-SF8-GF0.25-XSF0.75 (i.e.75% recycled coarse aggregate, 8% cement replacement with silica fume, 0.5% glass fibre, and 0.5% steel fibre). Similar trends were observed in split tensile and flexural strength. The study concludes that these combinations can be used for structural purposes.KeywordsHybrid fibresRecycled aggregate concreteStrength

Self-compacting concrete (SCC) is a flowing concrete mixture that is able to consolidate under its own weight. The highly workable nature of SCC makes it suitable for placing in complex structural elements and in sections with congested reinforcement. Utilization of industrial waste products in the construction industry draws serious attention of many researchers and investigators. In this study an experimental investigation has been carried out to study the significance of blast furnace slag as partial replacement for coarse aggregate in fly ash blended self-compacting concrete. The coarse aggregate was replaced by blast furnace slag at 10% to 100% and various tests were conducted to determine the optimum level of replacement of blast furnace slag in self-compacting concrete. The specimens were subjected to compressive strength, split tensile strength and flexural strength tests in addition to fresh concrete properties. Slump flow, J-ring test, L-box, U-box and V-funnel tests were carried out for evaluating fluidity, filling ability and segregation properties of the fresh concrete. Based on the overall observations it could be concluded that an increase in slag proportion increases the strength properties and among the various percentages of replacement 30% is found to be optimum for maximum strength properties.