Conventional Concrete Mix Research Articles

Investigating inherent cement setting mechanisms to improve the constructability performance of extrusion-based 3D concrete printing

AbstractThis research aims to utilize the inherent setting mechanisms of cement to 3D print a more conventional concrete mix without the addition of commercial accelerator admixtures, towards improved surface finish, pumpability or buildability. Three potential rapid setting mechanisms are investigated in this research, namely: flash setting, false setting and belitic calcium sulfoaluminate (BCSA) replacement of cement. The three rapid setting mechanisms are characterised by determining hardened state compressive strength, setting time and green-state compressive strength. Potential mixtures are then 3D printed and their performance quantified through buildability tests and observation of surface finish quality. Additionally, the economic feasibility is investigated. It is shown that false setting does not significantly influence the mechanical properties, while the early age strength gain is not as rapid as for flash setting or BCSA cement. Flash setting improves the early age strength but reduces the long-term compressive strength. Partially replacing OPC with BCSA cement improves the early age strength and does not impact the mechanical properties significantly. Higher cement replacements increased the intensity of the rapid setting mechanisms, shortening setting and increasing early age strength. Flash setting showed the largest positive impact on the buildability of 3D printed concrete. The buildability could be increased by 321% with flash setting, while BCSA cement resulted in a buildability increase of 214% and for false setting only a 35% increase. Flash setting and BCSA replacement are shown to be the more economical rapid setting mechanisms.

Mesoscale modelling of recycled aggregate concrete: A parametric analysis of properties of mesoscopic phases of RAC

This paper analyses the relative effects of ten parameters of recycled aggregate concrete (RAC) mix design on its mechanical properties. Research on the effect of the source concrete and of the quality of the interfacial transition zones (ITZ) on the properties of RAC is scarce and additional knowledge would guide RAC mix design towards efficiency and understanding of the effect of recycled aggregates (RA) on concrete. Therefore, this paper presents the outcomes of parametric numerical analyses on this topic. Within the range of parameters commonly found in conventional concrete mix design, it is found that: (1) the quality of both the old and new mortar substantially influences the mechanical behaviour of RAC. High-quality RAC can be produced with RA sourced from, at least, medium quality concrete (C40); (2) a poor-quality ITZ results in a significant decrease in concrete properties, particularly decreasing the tensile strength up to 58%, since micro-cracks that initiate in weak ITZ can readily develop into mortar; (3) the most relevant factors that determine the strength of RAC are the quality of mesoscopic phases, with the relative effects that range from 8% to 53% for compressive strength and from 22% to 59% for tensile strength; (4) the concrete mix design was less relevant, with a maximum influence of 23%; (5) the previous two observations imply that the most efficient way to improve the properties of RAC is to use RA of better quality; (6) a high proportion of coarse aggregates and a lower replacement ratio of natural aggregate with RA can effectively improve the stiffness of RAC by 16% and 15%. This paper contributes to understanding the influence of mix design and raw materials on the properties of RAC and determines the limiting factors that prevent a concrete mix from reaching its intended performance.

Investigating the effect of polypropylene fibres and curing parameters on the workability and mechanical properties of concrete

Polypropylene fibers possess certain characteristics that make them an ideal counterpart to attain explicit advantages when used for building works, more specifically, when added to concrete. In this investigation, polypropylene fibers were added by weight of cement (0.25%, 0.5%, and 0.75%) in M20 grade of concrete and their impact on workability, compressive strength, and flexural strength were assessed and analyzed. The slump test revealed that as the polypropylene fiber loading in the concrete mix was increased, the workability of the mixture continued to decrease; the workability decreased by 11.11%, 19.44%, and 45.83% upon the addition of 0.25 %, 0.5%, and 0.75% fibers respectively in the concrete. The compressive strength, as well as the flexural strength of the concrete, increased monotonously with an increase in the curing time and fiber loading. For instance, in the case of acidic water curing, the compressive strength enhanced from 19.08 MPa to 22.85 MPa upon increasing the fiber content from 0.25% to 0.75%. Adding 0.25% polypropylene fiber resulted in an increase in the flexural strength of conventional concrete mix by 15.78% and 10.29% when cured in normal water for 28 days and 56 days, respectively. Both the compressive and flexural strength of the samples cured in normal water was found to be higher than the samples cured in acidic water and it was observed that the fibre-reinforced concretes were more resistant to acids than the normal unreinforced concrete.

Assessing the Durability, Mechanical, and Microstructural Properties of Nanosilica-enhanced Coconut Shell Concrete: A Sustainable Approach

This study explores the properties of concrete as a sustainable substitute for cement through the use of nanosilica in an eco-friendly aggregate system. Daily life generates a larger amount of coconut shell waste from the tropical zone. In India, the yearly deposition of coconut shell is about 80,000 tonnes, which is 6.7% of total agricultural waste. Crushing gravel production emits CO2, which is an environmental concern. Simultaneously, to diminish waste disposal of coconut shell can be effectively utilised as coarse aggregate in lightweight concrete. The conventional concrete (CC) was fully replaced by coconut shell coarse aggregate and crushed gravel sand (Msand) as fine aggregate in plain Portland cement. Nanosilica replaces cement in the conventional blend at 0%, 1%, 2%, 3%, and 4%. This study describes the concrete's hardened properties, such as compressive strength, splitting tensile strength, and flexural strength. Among all the mechanical performances, the N2 blend is significant. The N2 mix exhibits a trend that aligns with the correlation between compressive strength and splitting tensile strength. The transport durability performance related to capillary wick action of the optimum blend (N2 mix) has 0.018 mm/min0.5. The pore filler mechanism and pozzolanicity of 2% NS is more synergic than other combinations. The N2 mix in H2SO4 environment has less mass and strength loss. The N2 blend's morphology is robust relative to the CC mix because of the secondary C-S-H gel and homogeneous, smooth hydrated grain. As a result, the report concludes that using coconut shell as an aggregate in concrete can reduce waste disposal in landfills, while using nanosilica in place of cement can reduce CO2 emissions.

Sustainable and strength-enhanced concrete using microbial consortia

The mechanical properties of concrete were examined by using steel fibres and two types of bacteria (Pseudomonas otitidis and Bacillus cereus). These steel fibres and bacteria were incorporated into the concrete mix in proportion to the weight of the cement. To ensure the resilience of microbial consortia incorporated into bio-concrete against the mechanical and chemical stresses encountered during concrete production, these microorganisms should exhibit critical characteristics, including robust alkali resistance and the ability to produce endospores. By employing 16S rRNA gene sequencing, we verified the identity of a group of organisms isolated from fermented lime mortar and curing construction water. Microbiologically induced calcite precipitation (MICP) was confirmed through microstructural analyses using techniques such as scanning electron microscope (SEM) and x-ray diffraction (XRD). The concrete was prepared with optimal concentrations of cultured bacteria (ranging from 103, 105 and 107 cells/ml), and steel fibres were added to the concrete at varying percentages (0%, 1%, 1.5%, and 2%). The optimal steel fibre content was 1.5%, and its strength properties were compared to conventional concrete. Notably, when Pseudomonas otitidis and Bacillus cereus bacteria were added to the traditional and optimal concrete mix, the compressive strength was significantly enhanced compared to the conventional concrete mix.

An Experimental Study on Properties of Microbial Blended Concrete

Several efforts are being made by researchers to turn concrete into a more sustainable material. Various research are being carried out to substitute cement in concrete, either whole or in part. The current work uses mineral admixtures like metakaolin and GGBS (blended concrete) to partially substitute cement in concrete. Concrete prone to cracking due to structural and Non-structural conditions. All kinds of fissures have the potential to harm concrete by letting water and other substances pass through them, which weakens and distorts the material while also compromising the reinforcing. To repair the concrete cracks, a certain type of treatment and routine upkeep are required, and they will be very costly. So, the current research is to study the impact of Bacteria (microbes) on crack healing as well as on properties of blended concrete. Different mixes of M25-grade concrete were done by using M-sand as fine aggregate to obtain the optimum percentage of GGBS used as supplementary cementitious material (0, 5%, 10%, 15%, 20%, 25%, and 30%), and the same percentage was used in blended concrete, which included metakaolin at different percentages (0, 5%, 10%, 15%, 20%, and 25%).Among different mixes, the proportions of blended concrete with enhanced mechanical properties were considered, and bacteria were induced at a constant percentage in that mix. The results indicated that the microbial blended concrete mix has significantly improved mechanical and durability properties, when compared to conventional and blended concrete mixes.

Experimental Analysis of Light Weight Concrete by Using of Light Weight Aggregat

This project investigates light weight concrete by replacing coarse aggregate with Light weight Aggregate (LWA). The methodology involves meticulous data collection, analysis, material selection, and the design of M30 grade concrete. It aims to evaluate how different proportions of LWA replacement affect concrete properties. Beginning with data gathering on conventional concrete mixes and LWA properties, material selection balances structural integrity with light weight characteristics. Varying percentages of LWA replacement (0%, 20%, 40%, and 50%) are then incorporated into the design phase, followed by precise mixing to maintain consistency. Concrete specimens undergo tests including slump, compaction factor, cube casting, and rebound hammer testing to evaluate workability, compact ability, and compressive strength. The project highlights the importance of the compressive test in determining concrete strength. Through meticulous analysis, it discusses LWA's effects on properties like workability, density, and durability, contributing insights into sustainable construction practices and emphasizing empirical analysis for engineering material selection. Key words LWA-Light Weight aggregate, LWC- Light Weight concrete, LECA- Light Weight expended clay aggregate, conplast SP430(G), Fosroc, SSD – Saturated Surface Dry, DRY WEIGHT – Dry Weight of Material.

ANALISIS PERBANDINGAN KUAT TEKAN BETON NORMAL DENGAN BETON CAMPURAN BAN BEKAS

This study evaluates the comparison of compressive strength between conventional concrete and concrete mix with used tire aggregate, focusing on its influence on compressive strength and concrete weight. The testing used cylindrical specimens with variations of used tire addition at 3%, 6%, 9%, and 12% of the coarse aggregate volume. The targeted concrete design strength is fc' 20 MPa at 28 days. Experimental methods were employed to compare their mechanical properties, measuring compressive strength and concrete weight across different mix compositions. The results for normal concrete yielded an average of 30.96 MPa, while for 3% tire mix yielded an average of 30.12 MPa, 6% tire mix yielded an average of 25.51 MPa, 9% tire mix yielded an average of 22.51 MPa, and 12% tire mix yielded an average of 21.54 MPa. The reduction in concrete weight for 3% tire mix was 0.035 kg from normal concrete, for 6% tire mix was 0.04 kg from normal concrete, for 9% tire mix was 0.23 kg from normal concrete, and for 12% tire mix was 0.35 kg from normal concrete. The study findings indicate that concrete mix with used tire aggregate exhibits competitive compressive strength with conventional concrete, while showing a tendency towards lower weight. The implication is that concrete mix with used tire aggregate has the potential to be a lighter and mechanically strong alternative. This study provides important insights for the construction industry in seeking more sustainable and cost-efficient solutions, while reducing the environmental impact of used tire waste.

On the computational evaluation of carbon dioxide emissions of concrete mixes incorporating waste materials: A strength-based approach

In the last decades, the high emissions of carbon dioxide during concrete production have pushed the scientific community to develop innovative ways towards reductions of such carbon dioxide emissions. An effective way is to use waste materials to replace conventional concrete materials, but this may come at the cost of reduced concrete performance. Hence, there is a need to link the carbon dioxide emission of concrete with concrete strength (strength-carbon dioxide emission relationship). This study bridges this gap by investigating the possibility of reducing carbon dioxide emissions in concrete by incorporating waste brick powder (WBP) and waste tire rubber (WTR) using a strength-based approach. This resulted in the formulation of three concrete grades of 20 MPa, 25 MPa and 30 MPa. It is shown that the impacts of including WBP and WTR on carbon dioxide emissions of concrete mixes are significant. Moreover, the compressive strength values corresponding to contents of 5 % WBP and 20 % WTR reduce dramatically by more than 32.57 % in comparison with conventional concrete mixes. However, 5P0T and 5P10T concrete mixes reveal both the reductions in carbon dioxide emissions and reasonable concrete strength. The present research therefore shows that certain concrete mixes incorporating WBP and WTR can provide the driving force for reducing carbon dioxide emissions and preventing substantial compressive strength reductions.

Performance evaluation of hybrid fiber reinforced concrete on engineering properties and life cycle assessment: A sustainable approach

Conventional concrete in its existing form possesses characteristics like better compressive strength, density, resistance against moisture and enhanced performance under various exposure conditions like elevated temperature and long-term durability etc. However, some of the shortcomings such as reduced ductility, brittleness can be improved by using additives like fibers to improve its properties. The present study highlights the performance evaluation of engineering properties and life cycle assessment (LCA) of hybrid fiber reinforced concrete (HFRC) incorporating with glass and polypropylene fibers in equal proportions (0%, 0.5%, 1.0%, 1.5%, and 2.0%). In addition to these, impact resistance at first crack phase and post cracking phase i.e., at failure have also been investigated to ascertain the effect of HFRC vs conventional concrete mixes. Sorptivity studies also performed to find its effect on HFRC, and control concrete mixes prepared with and without glass and polypropylene fibers. Reduction in workability of concrete was observed with increase in hybrid fiber content. Superior performance in terms of strength and durability properties was observed at 1% hybrid fiber content. Similarly, this study also focuses on studying the impact of HFRC and conventional concrete on environment using LCA approach. For LCA, SimaPro software and EcoInvent database is used to compare environmental impact assessment of HFRC and conventional concrete mixes. Impact on environment and cost comparison on HFRC mixes exhibits satisfactory results when compared to conventional mix. Finally, this research will address the need for HFRC mixes to achieve their adaptability in construction sector to make concrete economic and environmentally friendly.

DEMOLISHED WASTE INTO AN INNOVATIVE RESOURCE FOR SAND REPLACEMENT IN CONCRETE (THE DWARF TECHNIQUE)

The construction sector generates substantial waste, including demolished concrete, presenting environmental challenges and disposal expenses. This study introduces the DWARF (Demolished Waste as Resource for Sand in Concrete) technique, an innovative method that repurposes demolished waste as a valuable resource for replacing sand in concrete production. The DWARF process involves treating the demolished waste to meet specifications for sustainable use as an alternative to natural sand in concrete mixes. This research investigated the feasibility and effectiveness of the DWARF technique concerning its impact on concrete's mechanical properties and sustainability. Experimental tests evaluated the compressive strength, durability, and environmental performance of concrete mixes with varying percentages of demolished waste as a sand replacement. The results were compared with conventional concrete mixes to assess the DWARF technique's performance. The findings indicated the successful incorporation of demolished waste into concrete mixes using the DWARF technique, resulting in comparable or improved mechanical properties compared to conventional concrete and additionally, using demolished waste as a sand replacement reduces the environmental impact associated with sand mining and waste disposal. The DWARF technique supports sustainability by curbing natural resource consumption and endorsing the circular economy concept in construction. Moreover, the technique's economic viability was evaluated, considering potential cost savings in sand procurement and waste disposal. In conclusion, the DWARF technique offers a promising and innovative solution for converting demolished waste into a valuable resource for sand replacement in concrete production, contributing to sustainable construction, resource conservation, and waste reduction. Further research is needed to optimize and encourage its widespread adoption in construction projects.

Influence of Aggressive Environment in Macro and Microstructural Properties of Bottom Ash Geopolymer Concrete

India generates 759.02 million metric tons of coal ash annually. Part of that quantity is successfully utilized, and the remaining portion of the ash is discarded into a landfill. There also is a need to address pollution. Cement industries are responsible for 7% of global warming. Cement has been replaced entirely by thermal power plant waste, and bottom ash is used as a binder to overcome those issues. A few researchers have carried out strength characterization, but an extensive study needs to be carried out under different environmental exposures. Therefore, the present study investigated macro and micro properties of bottom ash geopolymer concrete (BAGPC) subjected to aggressive ecological exposure conditions such as acid, salt, and sulfate attack. Sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) of eight molarities were used as activators for the bottom ash geopolymer concrete (BAGPC) binder. Further bonding between steel and conventional concrete BAGPC mixes was investigated. The durability of conventional concrete (CC) was taken as the control mix to compare the durability of the optimized mix (B4) of bottom ash geopolymer. The test samples were cured for 28 days under ambient temperature and tested for the effect of MgSO4, NaCl, and HCl. The strength loss and weight loss of the BAGPC B4 mix after 7, 28, 56, 90, and 180 days under aggressive conditions showed better performance than CC. It has been observed that geopolymer concrete has good bonding in nature, and the bond strength results indicate excellent bonding between steel and concrete. Microstructure studies revealed that the BAGPC B4 mix had a strong microstructure and not as much of a porous structure. It is concluded that BAGPC has potential value in the construction industry based on all aspects of the experiment.

Rubber fibre reinforced geopolymer concrete with silica fumes as a replacement for fine aggregate

This experimental study deals with the upgrading of rubber fibre reinforced geopolymer concrete with silica fumes as replacement of fine aggregate. Researches are experimenting with replacing ordinary portland cement with GGBS as binder. GGBS has several positive environmental impacts. It reduces the carbon footprints of concrete producing by completely or partially replacing a portion of cement, which is a significant source of CO2 emission. In this experiment fine aggregate also partially replaced with silica fume by 10%,20%,30%,40% and 50%. Silica fumes is extremely fine particles, with high surface area and reactivity, make it an excellent material for enhancing the properties of concrete. When adding to concrete mixture silica fumes filled the voids between cement particles leading to denser and stronger concrete. Cube and cylinder are the specimens cured at 7 and 28 days for determining the mechanical properties like compressive strength and split tensile strength. Sodium silicate and sodium hydroxide were the alkali solution used as an admixture for the concrete grade-M30. The rubber fibres are added at 0.5%, 1%, 1.5% and 2% to the obtained optimum value. From 10%-50%, 30% of silica fumes in geopolymer shows the optimum mix when compared to conventional Portland cement concrete mix. Our project point to emphasize an advanced concrete mix that is sustainable, durable and ecofriendly for the construction field.

Full-scale static behaviour of prestressed geopolymer concrete sleepers reinforced with steel fibres

Profusive cracking leading to the deterioration of prestressed concrete sleepers has retained the sleepers from being exploited to their full extent. In addition, excess utilization of cement in producing the same has paved the way for developing its counterpart, geopolymer concrete (GPC), involving primary industrial residues as their precursors. This study presents a comprehensive investigation into the development and performance of high-strength geopolymer concrete sleepers for railway applications. The research focuses on the complete replacement of ordinary Portland cement with Fly ash and Ground Granulated Blast Furnace Slag in the geopolymer concrete mix, for mainline prestressed railway sleepers following Indian Railway Standards (IRS). Notably, the study includes experimental validations of long steel fibers as secondary reinforcement to the primary prestressing strands, aiming to enhance the ductility of the member. Experimental validations were performed on full-scale (1:1) sleeper members under static loading conditions. The main aim of this article was to assess the load carrying capacity at cracking and ultimate limits, rail seat bending moment, ductility indices, failure mechanism, electrical impedance, bond strength, and the eco-efficiency for the proposed prestressed geopolymer concrete sleeper members (with and without steel fibres) with reference to the conventional prestressed cement concrete sleepers. The considered GPC mix was found to achieve higher load and moment carrying capacity by about 8.3% and 8.54% respectively compared to the conventional concrete mix. The addition of steel fibres in the GPC increased the load and moment capacity of sleepers by 23% and 24.21% respectively. Additionally, the steel fibre reinforced GPC showed improved displacement ductility demand over the plain geopolymer concrete averaging 25%, 28.5%, and 3% corresponding to ultimate, failure, and residual ductility index respectively. Though inclusion of steel fibers improves the performance of sleepers in terms of load and ductility, they were found incompatible with regard to the electrical impedance property when used in conjunction with the pre-stressing strands.

Building earthquake resilience with clay shale: pioneering sustainable concrete solutions with eco-friendly materials

This study examines the potential of using locally sourced clay shale as an eco-friendly addition to concrete formulations, aimed at boosting both structural strength and seismic resilience in earthquake-prone regions. Optimized using the Dreux-Gorisse method, the clay shale-based concrete achieved a compressive strength of 12 MPa after seven days and 16 MPa after 28 days, meeting B25 concrete standards. Seismic testing with cyclic loading at a frequency of 1 Hz demonstrated notable ductility and deformation resistance, with a 9% increase in compressive strength compared to conventional concrete mixes. The use of clay shale also helped reduce the concrete's carbon footprint by approximately 12%, thanks to a reduced need for transported materials, making it a sustainable and cost-effective choice. These findings suggest that clay shale concrete offers a robust, resilient option for construction in seismic regions, balancing sustainability with structural reliability. Future studies should explore the material’s long-term durability and in-field performance to confirm its potential further. This study highlights the value of integrating geotechnical and seismic resilience into sustainable infrastructure, aligning with global goals to lower environmental impact and improve community safety.

Review- Using Ground Bakelite as Alternative Solution for the Replacement of Fine Aggregate

Abstract: India is very fast developing nation, and construction plays vital role in developing the nation. In construction, concrete is the majorly useful material. Fine aggregate used in concrete like traditional UHPC causes several environmental issues like floods due changes the direction of river flow, effect on biological diversity, falling water table also . In current time millions of tons of waste materials disposed in open environment which causes several health as well as waste disposal problems. We can use waste material like Bakelite as the partial replacement of fine aggregate. The purpose of this study is to find whether the use of Bakelite in concrete improve its compressive strength as a partial replacement in conventional M25 grade concrete Mix. From 2010 to 2020, river sand usage in Indian construction sector increased from 630 to 1400 Tons. This type of usage is very harmful for our next generation also that’s why many states in India like Bihar, Tamil Nadu, Madhya Pradesh, Rajasthan, Uttar Pradesh and Maharashtra have banned the river sand mining for use in concrete

Assessment of Strength of Concrete containing ESP and IESP as Partial Cement Replacement

In the present era of technically feasible and environmentally compatible low-cost material substitution with the basic ingredients of conventional concrete mix, the infusion of eggshell powder in its raw as well as incinerated forms was tried with the cement mantle. Experimentations carried out to endorse the compressive strength, split tensile strength, flexural strength, workability and durability aspects revealed that it had the edge over the properties standardized for the conventional concrete mix at a specific mix strength of 20 MPa. The experimental results for variations in the treatments of eggshell powder and incinerated eggshell powder corresponding to the responses on the evaluation parameters were compared with the conventional concrete mix by means of regression analysis and modelling. The regression model at more than 95% correlation level of the experimental data fortified the relative supremacy of eggshell powder and incinerated eggshell powder-infused concrete mixes over the conventional concrete mix in terms of workability, strength, and durability. Based on the statistical regression point of inflexion and the point of tolerance, it was clearly established that 20% optimal proportional addition of eggshell powder or 30% addition of incinerated eggshell powder could result in a superlative performance compared to the conventional concrete mix. This final outcome of the optimal combinations of eggshell powder and incinerated eggshell powder incorporated concrete (EPIC) was also test verified by SEM and EDAX analyses.

The Effect of Superplasticizer (SP) on the Workability and Skid Resistance of Geopolymer Concrete (GPC) Containing High Calcium Precursor (HCP)

A superplasticizer (SP) is one of the admixtures that may be used to improve the workability of concrete. However, its effects on geopolymer concrete (GPC) have yet to be well known or published, especially regarding its skid resistance and workability performance. This research aims to study the impact of the superplasticizer on the skid resistance and workability of geopolymer concrete containing high calcium precursor (HCP) in different proportions of SP, which are 0, 0.5, 1.0, 1.5 and 2.0 % by the weight of the HCP. Seven mix designs were produced: 1 conventional concrete mix, 5 geopolymers concrete mix, and 1 bituminous cold-mix asphalt mix. Slump flow and skid resistance tests were performed in this study. A skid resistance test is achieved using a British Pendulum Tester (BPT) on a 220 mm x 220 mm x 50 mm rectangle. This study found that the effect of SP on skid resistance is insignificant. However, the skid resistance of all GPC mix designs is higher than CC and asphalt mix. The workable flow of geopolymer concrete containing HCP and 0 - 2 % SP was 118-123 mm. However, less than 2 % of SP is given an insignificant difference. The optimum mix design of GPC is mix design GPC with an added 2 % SP (M6) that gives a high workability compared to other GPC mix designs and good skid resistance of 95 BPN. This study also found that workability correlates with skid resistance. The higher the spreading width value, the smaller the skid resistance value. In other words, the higher the flowability value, the less rough the sample surface. Hypothetically, the higher the percentage of SP, the higher the workability and the lower the skid resistance.

Behaviour of carbon or glass FRP-confined rubberised concrete under monotonic compression

This paper presents a comparative assessment of the compressive behaviour of rubberised concrete (RuC) confined with FRP jackets. In total, three RuC mixes were investigated with rubber content of 6%, 12% and 18% of the total aggregate volume, as well as a conventional concrete mix as a reference. A total of 100 cylindrical concrete specimens (Ø100 × 200 mm) subjected to monotonic axial compression were tested. Confinement scheme comprised 1 or 2 FRP layers of either carbon or glass uniaxial fabric. The mechanical properties, stress–strain behaviour, and confinement effectiveness ratios were assessed. The discussion includes a comparative assessment of the influence of rubber content, confinement and the type of fibre of the fabrics used on the aforementioned properties. The efficiency of analytical models in predicting the experimental results was also investigated. The results revealed a significant reduction of the compressive strength when crumb rubber was used as mineral aggregate replacement in concrete. FRP confinement of RuC was able to mitigate the reduction in compressive strength. Confinement of RuC with glass or carbon FRP jackets having similar axial rigidity resulted in similar stress–strain behaviour, which was mostly affected by the rubber content. Existing analytical models were able to predict the experimental results with moderate accuracy.

“The Exploration of a Double and Ternary Composite of Self-Compacting Concrete with Metakaolin and GGBS’’

Self-Compacting Concrete (SCC) is a modern form of concrete that does not involve vibration it during laying or compaction operations. The use of fine materials such as Metakaolin (MK) and GGBS can ensure the required concrete property. One possibility for minimising the cost of self-compacting concrete is to employ mineral admixtures such as Metakaolin and GGBS. It also lowers the heat of hydration. This study adopted (OPC 53) and M30 grade of concrete. In the first trail, MK was kept constant at 5% while GGBS was varied starting at 30% with increments of 5% (30%, 35%, and 40%). In the second trail, MK was kept constant at 10% while GGBS was varied starting at 30% with increments of 5% (30%, 35%, and 40%) replacement by the weight of Portland cement, and performance is assessed and compared to conventional concrete mix. The effect of mineral admixtures on self-compacting concrete workability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity, With a water cement ratio of 0.47 and manufacturing sand as fine aggregates and 12.5 mm coarse aggregates, a powder content of 520 kg/m3 (as per IS code10262-2019) is chosen as the binder material (Fine aggregate and cement) To improve the flow of the concrete, the superplasticizer poly carboxylate ether was used. As a result, self-compacting concrete's flow and filling capacities have significantly improved. MK5 (double blended mix) and MK5 + GGBS35 (triple blended mix) have higher 28-day strength than other mixes, while MK5 + GGBS35 has a higher modulus of elasticity than other mixes.