The impact of multi walled carbon nanotubes on the mechanical properties of polypropylene fibre reinforced concrete

• First study on flexural and fracture behavior of DβS-based geopolymer concrete. • 25–50% DβS improves modulus of rupture, fracture toughness, and ductility. • Peak CMOD and post-cracking behavior enhanced, reducing brittleness. • Life cycle assessment shows 72% lower global warming potential vs cement concrete. • DβS valorizes lithium waste, enabling sustainable low-carbon construction. Geopolymer concretes offer substantial environmental benefits, along with notable durability and mechanical advantages, relative to traditional cement concrete. However, geopolymer concretes exhibit relatively brittle fracture behavior and limited flexural performance when cured at ambient temperature. For the first time, this research evaluates flexural properties of ambient-cured geopolymer concrete prepared with delithiated β -spodumene (D β S), a lithium refinery residue. Four unique mixes were formulated by partial or full substitution of fly ash (FA) with D β S at 0% (control), 25%, 50%, and 75% of the total binder. Mechanical properties, including compressive and splitting tensile strengths, and fracture-related parameters of load-bearing capacity, crack mouth opening displacement (CMOD), modulus of rupture, fracture energy, fracture toughness and ductility index, were systematically evaluated. Results indicate that a partial replacement of FA with D β S (25–50%) significantly enhances the mechanical performances. Although the best results are obtained at 25% replacement, at 50% D β S replacement, the 28-day compressive and splitting tensile strengths increase by 10% and 8%, respectively, relative to the control concrete. Load-bearing capacity and peak CMOD improve by about 4%, while modulus of rupture, fracture toughness, and fracture energy increase by 4%, 33%, and 2%, respectively. The ductility index increases substantially at full FA replacement, reaching up to 2.2 times that of the control concrete. A life cycle assessment further confirms that increasing D β S content in geopolymer concrete substantially reduces environmental impacts, with the greatest benefits observed at 50% substitution. Overall, the findings demonstrate that D β S not only improves the mechanical characteristics of geopolymer concrete but also significantly enhances its flexural behavior and fracture resistance. This improvement is critical for the construction sector, as flexural performance governs crack resistance and ensures structural integrity of elements under bending stresses.

The development of sustainable high-performance concrete has increasingly emphasized the incorporation of natural fibers to improve mechanical and impact resistance. This study presents a comprehensive and novel investigation of multiple natural fibers, coconut (0.5–1.5%), flax (0.1–0.5%), jute (0.15–0.55%), and bamboo, hemp, and kenaf (0.25–1.25%), evaluated in two concrete grades (M25 and M80). In addition to experimental assessment, probabilistic reliability modeling was integrated to characterize the stochastic nature of impact behavior in natural fiber-reinforced concrete (NFRC). Repeated impact testing in accordance with ACI 544-2R demonstrated that coconut fiber at 1–1.25% provided the highest impact resistance, increasing failure counts by 65% in M25 and 83% in M80 relative to the control concrete. Kenaf (0.75–1%) and bamboo (0.5–1%) exhibited moderate improvements of up to 20%, whereas jute, flax, and hemp produced comparatively modest gains of 5–10%. Despite substantial improvements in impact resistance, compressive strength remained comparable to that of the control concrete. Ductility indices and post-cracking ratios revealed distinct post-peak deformation mechanisms governed by fiber type, including pull-out, rupture, and interfacial slip. To further quantify performance differences, a grade–fiber synergy analysis was proposed to evaluate the interaction between concrete strength and fiber efficiency across grades. The probabilistic characterization of impact resistance was performed using Weibull statistics, supplemented by bootstrap resampling and Bayesian uncertainty analysis, enabling assessment of reliability and parameter stability. The results establish a reliability-based framework for optimizing NFRC formulations to improve structural resilience under dynamic loading.

ABSTRACT During metal casting processes, large quantities of Spent Foundry Sand (SFS) are generated as waste, making its proper disposal a current research focus in industrial solid waste management. This study investigates the suitability of SFS by replacing natural river sand at equal mass ratios of 5%, 10%, 15%, and 20% to produce green concrete, with subsequent testing of compressive strength (CS), splitting tensile strength (STS), and chloride ion permeability. The results demonstrate that in terms of mechanical properties, at 28 days of curing, a 15% SFS substitution achieved maximum increases of 26% in CS and 12.87% in STS compared to control concrete. Regarding durability, the 28‐day SFS green concrete showed a 7.2% to 17.7% reduction in electrical flux relative to the control group. A recognized limitation is the use of SFS from a single source; future work should validate these findings with SFS from varied origins and include statistical robustness analysis. Furthermore, SEM/EDS analysis revealed that SFS primarily functions as a pore‐filling material without generating new hydration products. These findings indicate that using untreated SFS as a river sand substitute in concrete production reduces manufacturing costs and environmental pollution and enhances mechanical performance and durability. This “zero‐treatment” strategy provides a direct, scalable, and genuinely circular pathway for industrial waste valorization, demonstrating significant potential for large‐scale, sustainable concrete production.

CO 2 emissions from cement production have significantly increased, leading to the search for alternative materials that optimize the process and reduce environmental impact. In this context, the present study investigates the use of microsilica (MS) and fan shell powder (PCA) as cement replacements. Material characterization tests were conducted, and six mix designs were made, including 5% PCA and 10% MS replacements individually, as well as combinations of 10% MS with 5%, 7.5%, and 10% PCA. Additionally, compression strength properties were analyzed at 3, 7, and 28 days, and flexural strength at 7 and 28 days. The findings regarding mechanical strength were favorable, except for the mix with 10% MS and 10% PCA, which indicates the maximum substitution percentage. Furthermore, a CO 2 emission analysis was conducted according to the Greenhouse Gas Protocol, achieving a reduction of up to 11.16% compared to the control concrete. In conclusion, the study demonstrates that the combination of 10% MS and 5% PCA is the optimal replacement, improving compressive strength by 6.99% and flexural strength by 1.33%, while reducing CO 2 emissions by 10.44%.

This study investigates the strength performance of different lightweight concretes using polystyrene, palm kernel shell, and pumice as replacements for traditional coarse aggregates in a consistent 1:2:4 mix ratio. Lightweight concrete offers potential advantages in reducing structural weight while maintaining adequate strength for various applications. A control mix of regular concrete with the same 1:2:4 ratio was prepared to serve as a benchmark. The mechanical properties of both the lightweight and control concretes were evaluated through compressive, tensile, and flexural strength tests at curing periods of 7, 14, 21, and 28 days. In addition, workability was assessed using slump tests, while water absorption tests were performed to evaluate porosity. The findings demonstrated that the lightweight aggregates considerably decreased the density of the concrete to values within the lightweight concrete range (1402–1979 kg/m³), as opposed to normal concrete density of not less than 2400 kg/m³. Pumice was the most effective lightweight aggregate overall, with a compressive strength of 11.22 MPa at 28 days (about 70% of the control) and improved flexural and tensile strength in comparison to other lightweight mixes. Although polystyrene demonstrated the lowest structural performance (2.05 MPa at 28 days), it gave exceptional moisture resistance and intermediate strength (6.30 MPa at 28 days) compared to palm kernel shell. The high porosity of pumice (15%), the low absorption of polystyrene (0.3%), and the intermediate value of palm kernel shell (8%), was all highlighted by water absorption tests. According to the results, polystyrene is a good lightweight aggregate for non-structural or insulating applications, palm kernel shell is recommended for moderate-strength, sustainable applications, and pumice is recommended for applications where strength and weight reduction must be balanced. Granite is still the best material for strong structural components.

This study aims to develop and ascertain cost-effective, highly chemically stable, superhydrophobic, antimicrobial coatings to enhance the durability of concrete in aqueous and wastewater environments, which are typically challenged by microbial contamination, chemical erosion, and long-term exposure to corrosive ions. For this purpose, the performance of five organic coatings modified with stearic acid (STA) and nanoparticles (CuO, SiO2, and TiO2) was assessed in terms of self-cleaning, water absorption, chemical resistance, stability in chloride environments, resistance to sulfuric acid, antimicrobial properties, durability against UV radiation, and mechanical strength. The results revealed that the applied coatings led to a 57.42% reduction in water absorption compared to control concrete and provided effective self-cleaning behavior. The modified concrete revealed remarkable chemical stability in different pH environments, 27 wt% NaCl solution, and sulfuric acid solution, such that following immersion in sulfuric acid, the water contact angle (WCA) was still maintained above 130°. Further, two coatings, STA/TiO2 and STA/CuO indicated excellent resistance against microorganisms present in wastewater. These coatings also provided high mechanical durability and adhesion against UV radiation, abrasion cycles, and tape peeling tests. Overall, the results demonstrate that the developed coatings can be an efficient and economical option to boost the durability and performance of concrete in industrial applications and corrosive environments.

This study investigated the influence of graphene oxide (GO) on enhancing the mechanical characteristics and microstructure of concrete made of slag cement. Concrete samples were made with and without GO, added in varying dosages from 0.01% to 0.1% by weight of cement. The mechanical performance of these specimens was evaluated through compressive, tensile, and flexural strength tests. The durability was checked through acid and sulphate attack tests. To ensure uniform dispersion of GO within the matrix, polycarboxylate ether-based superplasticizer was employed at a measure of 0.25% by weight of cement. Scanning electron microscopy (SEM) was conducted to observe the microstructural development, while energy-dispersive X-ray spectroscopy (EDX) and X-ray Diffraction (XRD) were used to check the composition of the elements of the GO-modified matrix and its contribution to concrete health. The study found that GO addition is beneficial in enhancing compressive, tensile, and flexural strength up to 61, 109, and 39% at 28 days in comparison with conventional concrete. The acid and sulphate resistance of GO-modified concrete was found to be 46% and 30% better than that of control concrete. The effect of GO up to 0.05% on the properties of concrete is found in an increasing trend. SEM analysis confirmed improved dispersion of GO and enhanced interfacial bonding with cement particles. The EDX and XRD analyses validated the macro-level results. These findings highlight the potential of GO as an effective nanomaterial for improving the performance of slag cement-based composites.

The high consumption of natural aggregates in concrete production has led to increased exploitation of natural resources, causing environmental degradation. At the same time, the natural stone industry, particularly Onyx stone processing, generates a significant amount of solid waste that has not been optimally utilized. This study aims to evaluate the effect of using Onyx stone waste as a partial substitution for coarse aggregate on the compressive strength of concrete cylinders and the aesthetic quality of concrete surfaces. A quantitative approach with a pure experimental method was employed. Concrete cylinder specimens with a diameter of 150 mm and a height of 300 mm were prepared with Onyx waste substitution levels of 0%, 10%, 20%, and 30%, with five specimens for each variation. Compressive strength testing was conducted at 28 days in accordance with SNI 1974:2011, while aesthetic aspects were evaluated through visual observation of the concrete surface. The results indicate that Onyx waste substitution of up to 10% does not cause a significant reduction in compressive strength compared to control concrete, with an average value of 28.16 MPa. However, substitutions of 20% and 30% result in statistically significant strength reductions. In terms of aesthetics, higher Onyx content enhances surface color variation and texture. Therefore, the use of Onyx stone waste is recommended as an alternative coarse aggregate up to a maximum level of 10% to achieve environmentally friendly concrete with adequate mechanical performance and improved aesthetic value.

Durability remains one of the key factors determining the long-term performance and service life of concrete structures. This study investigated a novel way to use waste dolomite powder (WDP) in concrete, aiming to develop a ternary aggregate system that simultaneously improves mechanical properties and durability. Experimental results showed that incorporating WDP in the concrete increased the 90-day compressive strength by up to 21.06% and the splitting tensile strength by 10.84%. Meanwhile, durability was significantly enhanced: compared to that of the control concrete, the reductions in drying shrinkage, water absorption and chloride migration coefficient of the concrete containing WDP were up to 17.27%, 35.59%, and 43.20%, respectively. The XRD, FTIR, and TGA results verified that WDP provided a stable crystalline phase dolomite (CaMg(CO 3 ) 2 ) which contributes to maintaining long-term dimensional stability. Acting as a micro-aggregate, WDP effectively filled into pores and refined the interfacial transition zone (ITZ). Pore structure analysis confirmed that the cumulative pore volume decreased by up to 21.83%, while the content of the harmless pore content (≤ 20 nm) increased by 35.49%. The SEM-EDS and Vickers hardness measurements further showed a narrower ITZ. Notably, the microhardness of the ITZ and the matrix were improved by 38.38% and 39.62%, respectively. In addition, the life-cycle assessment results show that incorporating WDP in concrete effectively reduced CO 2 emissions, energy consumption, and economic costs. These findings demonstrate that WDP can be effectively utilized to produce more sustainable concrete with superior durability and mechanical performance.

Recycled concrete aggregate (RCA) exhibits challenges like weak bonding, high porosity, and inferior strength compared to natural aggregates. This study evaluates the effect of epoxy resin polymer treatment on RCA on enhancing compressive and split tensile strengths in concrete, replacing natural aggregates with untreated RCA (UTRAC) and treated RCA (ERTAC) at 25%, 50%, 75%, and 100% levels. The tests were conducted at 3, 7, and 28 days. UTRAC showed reductions of up to 26.32% in compressive strength and 35.38% in tensile strength at 100% replacement; ERTAC outperformed control concrete (CC) with gains of up to 26.32% in compressive strength (at 25%) and 122.73% in tensile strength (at 100%), identifying 25% as the optimum replacement ratio. SEM and XRD analyses confirmed improved particle packing, reduced porosity, and stronger interfacial transition zones (ITZ) in ERTAC.

Currently, many researchers use industrial or agricultural by‐products (waste) as raw materials for the construction sector. These wastes are economical and help preserve the environment through good waste management. For this purpose, oil palm mesocarp fibers (OPMFs) are used at various volume concentrations (0%, 0.25%, 0.5%, and 1%) for the production of OPMF‐reinforced concrete aged 7, 14, and 28 days. The aim of this research was to investigate the properties of both fresh (spreading, occluded air, and density) and hardened (density, flexure, and compression) reinforced with OPMF, using MANOVA analysis. The experimental results of fresh concrete showed that the addition of OPMF volume fractions in the concrete reduced its workability compared to the reference concrete (0% OPMF concrete), while the entrapped air content increased relative to the control mix. The density showed an expected reduction relative to the control concrete. Furthermore, MANOVA evaluation of the hardened concrete properties demonstrated that the density of OPMF‐containing concrete was markedly lower than that of the reference mixture. Almost similar variations are observed with regard to the flexural and compressive strength of OPMF concrete.

Introduction.In the conditions of Southern Kazakhstan, irrigation canals play a crucial role in supplying water for agricultural production.The operation of conventional concrete linings is complicated by their low resistance to cracking, frost heave, abrasive wear, and exposure to aggressive environments.These factors lead to increasing filtration losses, which in some cases exceed 20-25% of the water supplied volume-an especially critical issue for a region characterized by a sharp continental climate and limited water resources.To improve the durability and impermeability of hydraulic structures, a modified concrete (MC) mixture incorporating a combination of mineral and chemical additives has been developed.Materials and Methods.The composition of the MC includes Portland cement and slag-Portland cement, quartz sand, granite coarse aggregate, silica fume (7% of the cement mass), fly ash, an air-entraining agent (0.05%), and hydrophobizing components.The experimental investigations were conducted in accordance with relevant GOST standards: compressive and splitting tensile strength (GOST 10180), frost resistance (GOST 10060), water impermeability (GOST 12730.5),abrasive resistance (GOST 13087), and sulfate resistance (GOST 31384).The micro-and nanostructure of the material was analyzed using SEM, EDS, and XRD methods.Results and Discussion.Compared with the control concrete (CC), the modified concrete demonstrated significant performance improvements: an increase in compressive strength up to 55 MPa (+14.6%) and in splitting tensile strength up to 4.6 MPa (+27.8%); an increase in frost resistance from 220 to 320 cycles (+45%); an improvement in water impermeability from W6 to W9 (+50%); enhanced abrasion resistance by 26.9%; and an increase in the sulfate resistance coefficient by 11.5%.Microstructural analysis revealed densification of the cement matrix, a reduction in macroporosity, and an increase in the content of low-basic C-S-H phases, which confirms the material's enhanced durability.Conclusion.The developed modified concrete exhibits a comprehensive improvement in operational performance, ensuring a 30-40% extension of the service life of canal linings and a reduction in filtration losses by up to 20%.Its implementation in the construction and rehabilitation of irrigation canals in Southern Kazakhstan will enhance water-use efficiency and improve the resilience of hydraulic structures under aggressive environmental impacts and persistent water scarcity.

Concrete is generally reinforced with steel bars tied together with annealed fibers, a process that generates metal fiber scraps, a form of construction waste. The presence of these residues around the construction site is a subject of debate among professionals; some see them as potential reinforcement of concrete, whereas others consider them as waste. This study aimed to evaluate the influence of adding annealed fiber scraps on the physical and mechanical properties of ordinary concrete. Composites were designed with fiber contents ranging from 0 to 0.75% of the concrete volume. Tests were carried out on cylindrical specimens (Ø16 cm, H32 cm) for most characterizations: compression and splitting tests, and on prismatic specimens (7×7×28 cm³) for flexural strength. After wet curing at room temperature of the laboratory (22±2°C) for 7, 14, and 28 days, the samples underwent a series of physical and mechanical tests. The results showed that workability decreased gradually as fiber content increased. Apparent density, water-accessible porosity, and capillary water absorption slightly increased with fiber content, reaching a maximum at 0.75%. On the other hand, the mechanical properties are improved: the compressive strength, splitting tensile strength, and dynamic modulus of elasticity increase significantly, with optimal gains of 15%, 18%, and 12%, respectively, compared to the control concrete. The addition of fibers also reinforced the concrete, as shown by the stress-strain curves. Those for fiber-reinforced concrete showed a slight improvement in the flexural tensile strength and displacement to failure, and a post-peak stabilization phase highlighted by the higher residual strength with fibers, unlike the control concrete, which showed brittle failure without a stabilization phase. Considering these results, annealed fiber scraps can be used as reinforcements in ordinary concrete, particularly for structural elements subject to bending, such as floors, beams, and slabs.

Cracks in building envelopes reduce service life and look poor. They let in water and salts. They drive up maintenance. This study tests aluminum as a green crack control option for thin concrete skins. We use recycled aluminum mesh and short wires. We pair them with low alkali binders and thin protective coatings. The goal is to form many fine cracks, not a few wide ones. We built mixes with a geopolymer paste and a slag rich blended cement. We compared them to a plain cement control. Coatings included anodized oxide, ceramic sol gel, and powder epoxy. We ran restrained ring, direct tension, pullout, and corrosion tests. We also cycled temperature and measured flow through cracked panels. Aluminum mesh in low alkali binders cut crack width at service. Mean width stayed at or below 0.2 millimeter. Crack spacing was tight and stable under cycles. Coatings reduced corrosion current by large margins. The ceramic layer stayed stable in heat and water. Water flow through microcracked panels fell to near zero with a light sealer. Panel mass dropped due to the light metal and thin mesh. Using recycled feedstock lowered embodied carbon. End of life recovery is simple with common sorting tools. The method suits nonstructural skins. It needs isolation from any embedded steel. Field trials and design charts are the next step. Results outline a practical path for durable facades.

This study experimentally investigates the radiation shielding performance, characterized by the linear attenuation coefficient (LAC) values, of concrete mixes incorporating lead monoxide (NL), nano-magnetite (NM), and nano-granodiorite (NG) as partial cement replacements (1–5%) under ambient and elevated temperatures (400–800 °C). The primary objective was to develop robust predictive models for the LAC values using Response Surface Methodology (RSM). Results showed that exposure to elevated temperatures notably reduced the LAC of the control concrete, especially after heating to 800 °C. Incorporating nanomaterials effectively mitigated this deterioration, maintaining higher shielding efficiency. NL mixes showed the greatest improvement, with LAC increases of about 42.6% and 37.4% after exposure to 600 °C and 800 °C, respectively. NM mixes ranked second, enhancing LAC by 26.7% and 24.2% at the same temperatures, while NG provided moderate improvement of around 9.9% at 800 °C (4% replacement). The superior performance of NL and NM mixes is attributed to their high density and atomic number, which promote photon absorption and scattering within the concrete matrix, as well as the improved microstructural integrity resulting from the filler effect of the uniformly dispersed nanoscale particles. Analysis of Variance (ANOVA) confirmed the high statistical significance and predictive power of the developed model, demonstrating an exceptional correlation between predicted and experimental data. The response surface analysis revealed that the nanomaterial dose and type are the dominant factor for enhancing LAC values, exhibiting a strong positive correlation, whereas elevated temperature has a detrimental effect. The observed curvature in the response surfaces confirmed significant non-linear and interaction effects between the input parameters. Optimization results demonstrated that a 5% nano-dose at various temperatures maximizes shielding performance, with NL identified as the most effective material, demonstrating superior radiation shielding properties.

Purpose The present investigation uses recycled aggregates (RA), fly ash (FA) and manufactured sand (MS) to examine the bond performance of concrete. Various mixes (M1, M2, M3, M4 and M5) were developed by incorporating hybrid fibres with FA and MS. After being exposed to high temperatures (2000C, 4000C and 6000C) for 2 h durations, the compressive strength, flexural strength (fL) and bond strength were assessed and compared to control concrete (M1). Numerous researchers have investigated the bond strength and residual strength of natural and alternative aggregates. There is an observed gap in the literature on the bond properties and residual concrete strength, including MS and RCA as well as hybrid fibre-based mixes containing MS after being exposed to sustained elevated temperatures. Hence, this research can be a value addition, since it provides a solution for the usage of RCA, FA and MS in the manufacturing of concrete, which reduces the consumption of natural resources and finds a solution for waste disposal. Design/methodology/approach The tests were conducted for different mixes, which include control concrete, concrete with fibres and concrete containing recycled concrete aggregates (RCA). M30 grade concrete with a 0.45 w/c ratio has been considered for the present study, and the natural coarse aggregates (NCA) were replaced with 50 and 100% of RCA. In addition, the behaviour of these mixes was studied at elevated temperatures of 2000C, 4000C and 6,000C for 2 h of sustained temperature in a specially designed electric oven with well-controlled instrumentation. The residual compressive strength, flexural strength, thermal conductivity and pull-out test with parameters, namely mean bond strength, mean slip and mean normalised bond strengths, were evaluated at these temperatures. Findings It was observed that the mixes with blended fibres are found to perform better in terms of actual and residual strengths. Though the recycled aggregate concrete mixes performance is marginally lower than control concrete, the results are well acceptable from the point of practical applications. Originality/value Unlike prior research, which focused primarily on post-fire mechanical strength, this investigation focuses on the bond behaviour of specimens made of RCA, fly-ash and hybrid fibres. It has been found that specimens containing hybrid fibres perform better than other combinations in terms of bond strength.

Abstract This study evaluates the thermal properties and effects of elevated temperatures on the residual properties of concretes containing lithium slag (LS) at cement replacement levels of 20%, 40%, and 60%. The results indicate that LS reduced the thermal conductivity of concrete by 1.08%, 4.47%, and 14.31% for using 20%, 40%, and 60% LS, respectively, while decreasing thermal diffusivity with the addition of LS. Conversely, volumetric heat capacity increased from 1.85 MJ/m 3 ·K (control) to 1.87, 1.92, and 2.06 MJ/m 3 ·K, indicating enhanced heat‐retention capability with the increase of LS content. In the elevated temperature tests, the 20%–40% LS concretes showed finer cracks compared to those in the control and 60LS concretes. No spalling was observed up to 800°C. Mass loss increased with the increase of temperature, reaching 7.2% at 600°C for the 60LS mix, whereas the 20%–40% LS concretes showed slightly lower mass losses than the control. Residual compressive strength also decreased with the increase of temperature, with the 20%–40% replacement retaining higher strength up to 600°C, while the 60% LS concrete experienced the highest strength loss. Ultrasonic pulse velocity results indicated progressive internal degradation, with a notable drop at 800°C. TGA confirmed enhanced thermal stability in the 20%–40% LS concretes through reduced Ca(OH) 2 decomposition and increased formation of stable hydration products. The SEM analysis showed denser microstructures in the 40LS mix compared to higher porosity in the control and 60LS concretes. Overall, the 20%–40% LS concretes demonstrated superior thermal resistance and high‐temperature performance.

This study looks at the mechanical and dynamic properties of Crumb Rubber-modified Concrete (CRC) with replacement levels. Compressive, tensile, and flexural strengths, modulus of elasticity, workability, and density were all measured experimentally, while dynamic response was analyzed using impact testing and ABAQUS simulations with the Concrete Damaged Plasticity (CDP) model. The results demonstrated lower workability, with slump values of and compacting factors of , qualifying (CRC) as low-workability concrete. Compressive strength fell from (control) to for , , and CR, respectively. Tensile and flexural strengths decreased, whereas the modulus of elasticity decreased by at CR, indicating reduced stiffness but increased ductility. ABAQUS simulations using the Concrete Damaged Plasticity (CDP) model aligned with experimental results. Control concrete failed in a brittle manner, but mixes containing CR exhibited enhanced ductility, delayed crack localization, and increased energy absorption, confirming the potential of CRC in seismic and impact-resistant applications. Under dynamic loading, CRC mixtures showed delayed fracture propagation and increased energy absorption compared to brittle failure in control specimens. Overall, CR provided a balance of strength and sustainability while CR improved ductility for seismic/impact-prone structures.

The nickel processing industry produces a large amount of solid waste in the form of nickel slag, which has the potential to pollute the environment if not properly managed and utilized. This study evaluates the use of nickel slag as a partial substitute for coarse aggregate in the production of high-strength concrete. Tests were conducted using cylindrical specimens with a diameter of 10 cm and a height of 20 cm, with variations in nickel slag content of 25%, 50%, and 75% of the total coarse aggregate. Based on the compressive strength test results, it was found that a 50% nickel slag composition was the most optimal variation, producing an average compressive strength of 46.31 MPa, which is an increase of 10.18% compared to the control concrete at 42.03 MPa. This improvement is influenced by the physical and chemical characteristics of the nickel slag, such as its rough surface that enhances interlocking between aggregate particles, as well as the presence of silica compounds that act as pozzolanic materials.