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The incorporation of waste materials generated in many industries has been actively advocated for in the construction industry, since they have the capacity to lessen the pollution on dumpsites, mitigate environmental resource consumption, and establish a sustainable environment. This research has been conducted to determine the influence of different rice husk ash (RHA) concentrations on the fresh and mechanical properties of high-strength concrete. RHA was employed to partially replace the cement at 5%, 10%, 15%, and 20% by weight. Fresh properties, such as slump, compacting factor, density, and surface absorption, were determined. In contrast, its mechanical properties, such as compressive strength, splitting tensile strength and flexural strength, were assessed after 7, 28, and 60 days. In addition, the microstructural evaluation, initial surface absorption test, = environmental impact, and cost–benefit analysis were evaluated. The results show that the incorporation of RHA reduces the workability of fresh mixes, while enhancing their compressive, splitting, and flexural strength up to 7.16%, 7.03%, and 3.82%, respectively. Moreover, incorporating 10% of RHA provides the highest compressive strength, splitting tensile, and flexural strength, with an improved initial surface absorption and microstructural evaluation and greater eco-strength efficiencies. Finally, a relatively lower CO2-eq (equivalent to kg CO2) per MPa for RHA concrete indicates the significant positive impact due to the reduced Global Warming Potential (GWP). Thus, the current findings demonstrated that RHA can be used in the concrete industry as a possible revenue source for developing sustainable concretes with high performance.

This work focuses on examining the mechanical characteristics and flexural response of reinforced concrete (RC) beams by incorporating oil palm shell (OPS) lightweight aggregate from oil palm shell waste. The OPS aggregates are replaced in various percentages, such as 0 to 50% of natural coarse aggregate (NCA). Mechanical properties of OPS concrete were conducted, and these properties were used to quantify the flexural performance of RC beams. Five RC beams with several gradations of OPS aggregates were cast and tested for this investigation. The first cracking, ultimate strength, load-deflection behavior, ductility index, and failure patterns of OPS aggregate beams were investigated as the corresponding behaviors to the NCA concrete beam. The fresh properties analysis demonstrated lessening the slump test by varied concentrations of OPS concrete. Furthermore, compressive strength was reduced by 44.73%, 50.83%, 53.33%, and 57.22% compared to 10%, 15%, 20%, and 50% OPC substitution at 28 days. Increasing OPS content in concrete mixes decreased splitting tensile strength, comparable to the compressive strength test. Modulus of rupture and modulus of elasticity experiments exhibited a similar trend toward reduction over the whole range of OPS concentrations (0–50%) in concrete. It was revealed that the flexural capacity of beams tends to decrease the strength with the increased proportion of OPS aggregate. Moreover, crack patterns and failure modes of beams are also emphasized in this paper for the variation of OPS replacement in the NCA. The OPS aggregate RC beam’s test results have great potential to be implemented in low-cost civil infrastructures.

This research work is devoted to the experimental investigation of both rheological and mechanical properties of self-compacting concrete (SCC) produced with waste galvanized copper wire fiber and rice husk ash (RHA). In the study, three different volume fractions of 0.5 p to 0.75 percent, 1 percent of scrap copper wire fiber as reinforcing material, and 2 percent RHA as cement replacement were used. To evaluate the fresh characteristics of SCC, the slump flow, J-ring, and V-funnel experiments were conducted for this investigation. Compressive strength, splitting tensile strength, and flexural strength of the concrete were conducted to assess the hardened properties. The test was carried out to compare each characteristic of plain SCC with this modified SCC mixture, containing RHA as pozzolanic materials and copper fiber as reinforcing material. Incorporating copper fiber in the SCC leads to a drop in fresh properties compared to plain SCC but remains within an acceptable range. On the other hand, the inclusion of 2% RHA makes the SCC more viscous. Although adding 2% RHA and 1% copper wire in SCC provide the highest strength, this mix has an unacceptable passing ability. The SCC mix prepared with 2% RHA and 0.75% copper fiber is suggested to be optimum in terms of the overall performance. According to this study, adding metallic fiber reinforcement like copper wire and mineral admixture like RHA can improve the mechanical properties of SCC up to a certain level.

PurposeThis study aims to present the variations of optimal seismic control of reinforced cement concrete (RCC) structure using different structural systems. Different third-dimensional mathematical models are used to examine the responses of multistory flexibly connected frames subjected to earthquake excitations.Design/methodology/approachThis paper examined a G + 50 multi-storied high-rise structure, which is analyzed using different combinations of moment resistant frames, shear walls, seismic outrigger systems and seismic dampers to observe the effectiveness during ground motion against soft soil conditions. The damping coefficients of added dampers, providing both upper and lower levels are taken into consideration. A finite element modeling and analysis is generated. Then the nature of the structure exposed to ground motion is captured with response spectrum analysis, using BNBC-2020 for four different seismic zones in Bangladesh.FindingsThe response of the structure is investigated according to the amplitude of the displacements, drifts, base shear, stiffness and torsion. The numerical results indicate that adding dampers at the base level can be the most effective against seismic control. However, placing an outrigger bracing system at the middle and top end with shear wall can be the most effective for controlling displacements and drifts.Originality/valueThe response of high-rise structures to seismic forces in Bangladesh’s soft soil conditions is examined at various levels in this study. This study is an original research which contributes to the knowledge to build earthquake resisting high-rises in Bangladesh.

The synergistic impact of waste slag and recycled steel fiber on high‐strength concrete (HSC) has been needed to produce eco‐friendly concrete in recent times. Consequently, this study aims to investigate the combined effects of waste slag and recycled steel fiber on the fresh, mechanical, and durability properties of HSC. Waste steel fibers (60 mm × 0.9 mm) were incorporated at 0.25%, 0.50%, and 0.75% by volume, levels selected based on practical ranges reported in literature and allowing evaluation of performance across incremental fiber additions, while slag replaced 15% and 30% of the cement by weight in the concrete mixes. Experiments assessed the workability, Kelly ball penetration, density, and compacting factor of fresh concrete, while mechanical characteristics (compressive, splitting tensile, and flexural strengths) were evaluated at 7, 28, and 90 days, and durability performance was tested through rapid chloride penetration, water absorption, sorptivity, and electric resistivity. Therefore, artificial neural network (ANN) and random forest (RF) were used as machine learning (ML) methodologies to predict the strengths of concrete. This research also explored the compressive strength to compare the nondestructive test with the destructive test results at 28‐ and 90‐day periods. The experimental outcome revealed that incorporating slag improved fresh workability (higher slump and compacting factor), while steel fibers slightly reduced it due to the interlocking effect. Additionally, the introduction of 30% slag and 0.75% steel fiber into HSC led to substantial improvements in compressive, tensile, and flexural strengths compared to the reference mix after 90 days. At 90 days, slag and steel fiber mixes showed up to 23% lower water penetration and slag‐only mixes achieved up to 82% higher electrical resistivity than the control, confirming improved durability. The SEM analysis of slag‐based concrete mixes revealed a denser and more homogeneous microstructure with reduced porosity, which correlates with the observed improvements in compressive strength, tensile strength, and durability performance. Building on these experimental insights, predictive modeling was performed, where the RF model showed better results than the ANN model for all three strength properties, with higher R 2 values (0.994, 0.992, and 0.996) compared to ANN (0.971, 0.932, and 0.948) and lower errors in terms of mean square error (MSE), root MSE (RMSE), and mean absolute error (MAE) than ANN.

Millions of used automobile tires are produced every year and it is an ever-growing challenge for solid waste management authorities. This study aimed to explore the fresh, mechanical, and durability properties of concrete integrating waste tires in the form of ground tire rubber (GTR) as a replacement for cement. Twelve concrete mixtures were prepared using 4%, 7%, and 10% GTR with a combination of Class F, Class C, and reclaimed fly ash. Experimental results showed that adding GTR to concrete reduced workability and improved air void quality compared to the control mixture. The incorporation of GTR in concrete reduced compressive, tensile, and flexural strength and elastic modulus. Furthermore, increasing GTR content in concrete increased drying shrinkage and sulfate attack expansion. However, the addition of GTR in concrete substantially reduced ASR expansion. Considering the overall performance, 4% GTR can be incorporated into producing concrete without jeopardizing its strength and durability.