Crumb rubber, resulting from recycled tyres, is used as an innovative material for rigid pavement application. By replacing fine aggregates in concrete mixes with crumb rubber, several benefits can be achieved, including improved performance, sustainability and potential cost savings while also addressing environmental concerns related to tire waste. This study explores the efficiency of two treatment techniques, water soaking and cement coating on crumb rubber utilized as a replacement for fine aggregate in concrete. Through a series of laboratory tests, including slump test and compressive strength test, the treated crumb rubber samples were evaluated and compared. The results indicate significant differences in the performance of crumb rubber based on the treatment method applied. The conventional concrete mix had a maximum slump of 47 mm. Adding water-soaked crumb rubber increased this to 68 mm for the WS-CR35 mix and 32 mm for the CT-CR35 mix, indicating improved workability. In contrast, the cement-coated rubber reduced slump value by 31.92

Cement production is a major source of global anthropogenic CO2 emissions. Although many studies evaluate decarbonization options, they often treat environmental impacts, mechanical performance, and economics separately. This approach makes it difficult to make decisions in the real world when there are trade-offs. This study proposes an integrated decision-support framework combining life cycle assessment (LCA), probabilistic cost modeling, 28-day compressive strength evaluation, and multi-criteria decision analysis (MCDA) using the technique for order preference by similarity to ideal solution (TOPSIS) to assess hybrid decarbonization pathways based on biomass wood chips, solar energy, and ground granulated blast furnace slag (GGBS) substitution. Six scenarios were modelled via SimaPro software using Ecoinvent datasets and the CML-IA baseline (v3.10) method. Relative to the baseline (906 kg CO2 eq./ton), the optimal hybrid scenario (S6), which comprises 50% GGBS substitution integrated with solar and biomass energy, reduced the global warming potential (GWP) by 62.9% to 336 kg CO2 eq./ton and achieved the lowest human toxicity impact (7.60 x 10(2) kg 1,4-DB eq.), representing a 97% reduction. Furthermore, the abiotic depletion potential of fossil fuels (ADPf) decreased by 33% (from 4.54 x 10(3) MJ to 3.04 x 10(3) MJ), quantifying the strategy's reduced reliance on finite resources.

The investigation looks at the effect load on a hybrid fiber-reinforced concrete with integrated lead zirconium titanate piezoelectric (PZT) induced by a 5 kg iron ball being dropped from heights of 2.5, 3.0, and 3.5 m one by one. The performance of the hybrid fiber-reinforced (polypropylene and glass) concrete’s (HFRC) mechanical characteristics under the impact loading was evaluated using the ‘electro-mechanical impedance (EMI)’ method. The compressive strength of the concrete was measured using a rebound hammer, before and after the impact. The ‘Root means square deviation’ (RMSD) was used to further quantify the conductance signature, which was acquired at frequency ranges from 0–600 kHz. The study indicates that the strength of concrete cubes decreases with impact height, causing more damage to both conventional and hybrid-fiber reinforced concrete. Hybrid fibre reinforced concrete tends to have lower conductance peaks, making it stronger than conventional concrete. The variation of the RMSD index illustrates how the real stiffness of the specimen diminishes with increasing impact energy-related damage. RMSD analysis revealed that the stiffness of HFRC decreased with increasing impact energy, with an initial RMSD value of 7.2

This study investigates the performance of hybrid fiber-reinforced concrete (HFRC) incorporating polypropylene and glass fibers under aggressive chemical environments. Concrete specimens of M30 grade were subjected to curing in sulfuric acid (H2SO4) and magnesium sulfate (MgSO4) solutions for evaluating short- and long-term mechanical properties. HFRC demonstrated enhanced durability with reduced mass loss and superior resistance to acid-induced degradation compared with conventional concrete. Compressive strength, rebound hammer tests, and microstructural analyses using scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) highlighted the role of hybrid fibers in mitigating crack propagation, improving the microstructure, and reducing porosity. Results confirmed that HFRC retained higher strength and mass stability under extended exposure to acidic and sulfate-rich conditions. This research underscores HFRC's potential for sustainable construction in chemically aggressive environments, ensuring enhanced durability and reduced maintenance costs for infrastructure applications. The study addresses gaps in chemical resistance, hybrid fiber synergy, varied curing conditions, and long-term durability, demonstrating hybrid fiber-reinforced concrete's superior performance in aggressive environments through advanced experimental analysis.

Crumb rubber (CR), a recycled elastomeric polymer derived from scrap tyres, has been used as a partial replacement for fine aggregates in concrete to manage non-biodegradable waste tyre piling, which fills landfills and harms the environment. Polymer-modified rubber improves the concrete's flexibility, toughness, and impact resistance, but reduces its strength and modulus of elasticity. Multi-walled carbon nanotubes (MWCNTs) are being used to mitigate these issues. The purpose of this study is to investigate the impact of CR% (1% to 5%) as a partial replacement for sand by volume and MWCNTs (at a percentage of 0.05% to 0.08%) as additives by weight of cement as input parameters for determining the mechanical strength (compressive, tensile, and flexural) and deformation properties (modulus of elasticity and Poisson's ratio) of MWCNT- and polymer-modified CR concrete using response surface methodology (RSM). The results show that 0.05% MWCNT and 1% CR content led to increases in compressive strength, flexural strength, and tensile strength by 14.12%, 11%, and 13.68%, respectively. In addition, models to predict those properties have been developed using RSM with a 95% reliability level. It has been observed that the notable development in the mechanical characteristics of CR concrete with the accumulation of MWCNTs and the models constructed using RSM were deemed satisfactory, with a variation of 0.05% to 0.065% of MWCNTs along with 2% CR.

The development of low carbon concrete systems requires synergistic strategies that improve performance while reducing clinker demand and enabling carbon utilization. This study investigates the combined effects of ground granulated blast furnace slag (GGBFS), carbonated mixing water (CW) and graphene oxide (GO) on the fresh, mechanical, and elastic properties of concrete. Unlike conventional carbonation approaches, CW was employed as the mixing medium to induce internal carbonation during early hydration, while GO was introduced to enhance microstructural efficiency. Response Surface Methodology based on Central Composite Design was adopted to systematically evaluate interaction of the variables and identify optimal mix proportions. The results reveal nonlinear behavior governed by the coupled action of slag hydration, internal carbonation, and nano scale reinforcement. Workability was primarily influenced by CW and GO dosage whereas compressive strength, flexural strength and modulus of elasticity exhibited peak values at intermediate GO levels, beyond which performance declined due to microstructural heterogeneity. Multi objective optimization identified an optimal mix comprising approximately 20.9% GGBFS, 53.6% CW and 0.032% GO achieving a balanced combination of high performance and adequate workability. Experimental validation confirmed strong agreement with model predictions with errors below 6%. Microstructural observations further verified the statistical findings, revealing a dense and homogeneous gel network in the optimized mix supported by controlled carbonation and effective slag participation, while excessive CW and GO led to localized agglomeration and performance deterioration. Environmental assessment demonstrated that the optimized mixture achieved reduced embodied carbon and improved carbon efficiency, with carbon intensity of approximately 4.59 kgCO2/MPa and emission reduction of nearly 16% compared to the control mix. This study confirms that slag, CW and GO can be effectively combined to design high performance and low carbon concrete systems.

The paper aims to investigate how cement mortar properties are affected by dissolved carbon dioxide in mixing water and use Response Surface Methodology (RSM) in the experimental work. The use of carbon dioxide-dissolved water is the main focus of this study, which aims to improve the properties of cement-based materials through CO2 mixing water. After three and seven days of curing, the cement mortar’s density, compressive strength, and modulus of elasticity are evaluated. According to preliminary findings, adding carbon dioxide-dissolved water to cement mortar improves its compressive strength, modulus of elasticity, and density. Using RSM modeling and optimization, it is found that 51.48

This study examines the coupled influence of ground granulated blast furnace slag (GGBFS) and carbonated mixing water (CW) on the mechanical behaviour and microstructural evolution of concrete, with a specific focus on the internal carbonation produced during hydration. Unlike external carbonation studies, the present work introduces CO2 directly through the mixing water allowing dissolved carbon species to interact immediately with calcium released from cement dissolution. A series of mixes incorporating 0-50 % GGBFS and 0-100 % CW were evaluated through compressive, split tensile strength testing along with non-destructive testing using rebound hammer and ultrasonic pulse velocity, supported by comprehensive microstructural characterisation. The results demonstrate that CW promotes in-situ precipitation of finely dispersed carbonate phases which serve as nucleation sites for C-S-H formation, leading to matrix refinement and enhanced early strength. Moderate slag replacement (25 %) produced an optimal balance between CaO availability and latent hydraulic reactivity, yielding a well-integrated C-A-S-H gel with embedded carbonate crystals. In contrast, excessive slag contents (50 %) reduced portlandite availability and shifted the system toward gel-dominated microstructures with limited crystalline carbonation. Analyses through FESEM-EDS, XRD, and TGA-DTG confirmed the coexistence of physical and chemical carbonation mechanisms, where a part of the CO2 was incorporated as carbonates along with chemically bound within the C-A-S-H gel phases. The findings demonstrate that a controlled degree of internal carbonation can simultaneously enhance strength, durability, and CO2 utilization in slag-blended systems, offering a viable pathway toward low-carbon cementitious materials.

Cement mortar is susceptible to microcracks due to various environmental factors, including weathering and chemical exposure. To address the issue, this study examines how calcined palm oil fuel ash (CPOFA) and cellulose microfibers (CMF) can be utilized to sustainably enhance the properties of cement mortar. By addressing the dual objectives of reducing cement consumption and finding productive uses for palm oil industry waste, this research addresses an important environmental challenge. Previous attempts to improve the performance of palm oil fuel ash (POFA) in cement-based materials through chemical and thermal modifications have not fully achieved the desired outcomes. To overcome these limitations, this research integrated CPOFA with CMF, leveraging their combined effects to enhance mortar performance. Using a user-defined option of response surface methodology (RSM), the study designed and tested nine different mortar mixtures, with CMF additions from 0 % to 2 % and CPOFA replacements of cement between 0 % and 40 %. These mixtures were evaluated for mortar flow, compressive, flexural, and splitting tensile strengths. Additionally, microstructural examination and X-ray diffraction (XRD) tests were conducted on selected samples to gain deep insight into the material interactions. The compact scanning electron microstructure coupled with high XRD peaks of Tobermorite and Portlandite from the XRD analysis of 1CMF-20CPOFA mortar sample maximized the development of dense cementation products due to its cementation reactions. The findings revealed that while increasing CPOFA content reduced both fresh and hardened mortar properties (mortar flow decreased from 90 % to 23 % at 0-40 % CPOFA), the addition of CMF significantly improved workability and strength, particularly at CMF contents between 1 % and 2 % and CPOFA levels below 20 %. At 20 % CPOFA, increasing CMF content from 0 % to 1 % enhanced 28-day compressive strength from 53 to 62 MPa, flexural strength from 5.3 to 6.6 MPa, and splitting tensile strength from 2.66 to 2.83 MPa. Through multi-objective optimization, the study identified the ideal mix ratios of 1.7 % CMFs and 11.3 % CPOFA, which were experimentally validated. The experimental results for the responses, including mortar flow, compressive strength, flexural strength, and splitting tensile strength, showed absolute relative deviations of less than 10 % from the corresponding predicted response values generated by the optimization. This approach not only demonstrates a more effective use of CPOFA but also highlights a sustainable, high-performance alternative for construction materials.

Strain-hardening cementitious composites (SHCC) are rapidly gaining popularity as building materials because of their remarkable ductility, increased tensile strain capacity, and controlled saturated microcrack propagation with tight crack width. Careful tailoring of materials and fiber-matrix interaction are credited to these exceptional properties. However, the primary challenges to the performance and widespread application of SHCC include the difficulty in achieving an optimum fiber-matrix bonding due to variations in surface properties at the interface, increased porosity because of the incorporation of polymeric fibers, and low modulus of elasticity and high shrinkage due to the absence of coarse aggregates and high cementitious material content. Extensive research has revealed that incorporating nanomaterials (NMs) into SHCC, either directly or as fiber pretreatment, can significantly enhance the matrix properties and the fiber-matrix interfacial transition zone. These enhancements address several key challenges, resulting in improved overall composite performance. Different types of NMs, such as nano silica (NS), and carbon-based nanomaterials—including carbon nanotubes/nanofibers (CNTs/NFs), graphene oxide (GO), and carbon black (CB)—influence SHCC behavior through multiple mechanisms. These mechanisms include refining the pore structure, improving the interfacial transition zone (ITZ) between the fibers, cementitious matrix, and aggregates, and providing additional nucleation sites for cement hydration products. These contributions lead to enhanced mechanical properties, durability, and energy absorption capacity. Furthermore, NMs play a crucial role in crack bridging and crack tip shielding, both of which are essential for achieving the strain-hardening behavior characteristic of SHCC. This review aims to explore the roles and effectiveness of various NMs in enhancing the critical properties of SHCC, including micromechanical, macromechanical, smart, and durability characteristics. By examining current trends in nanotechnology research applied to SHCC, the review seeks to inform future strategies for the efficient selection and application of nanomaterials in SHCC. The review's outcome is significant as it provides valuable insights into the influence of nanomaterials on improving the properties of SHCC. These improvements include reducing porosity, expediting cement hydration, inducing denser microstructure, enhancing fiber bridging capacity, stimulating self-healing and self-sensing capabilities, and boosting durability.

This study investigates the integration of coated piezoelectric (PZT) sensors in hybrid fibre-reinforced concrete (HFRC) beams to assess their potential in structural health monitoring (SHM). The research focuses on the role of various sensor coatings—nitrocellulose-based nail polish (NP), quick-set epoxy resin (RE), and epoxy putty (EG)—and explores the impact of coating thicknesses on sensor performance. The HFRC beams, reinforced with glass and polypropylene fibres, were embedded with coated and uncoated sensors and evaluated for their impedance properties across curing periods and under mechanical stress. Results indicate that NP and RE coatings provided superior electrical insulation and signal stability compared to EG, which exhibited higher conductance and reduced sensitivity. Thicker coatings enhanced durability but diminished the ability to detect fine structural changes. Optimal performance was achieved with 2–2.5 mm coatings, offering a balance between sensitivity and sensor protection. Experimental analyses revealed distinct trends in frequency-conductance behavior before and after damage, validating the efficacy of PZT sensors in identifying fractures. The findings underscore the potential of integrating advanced sensor technology with optimized coatings in HFRC beams for real-time damage detection and enhanced durability. This work contributes to advancing SHM systems, promoting safer and longer-lasting concrete infrastructure.

When two or more distinct types of fibres are used in conjunction with a combined matrix to produce a composite material known as a hybrid, this type of material can be referred to as a hybrid composite. This hybrid material represents the benefits of each of the individual components used in the fibres. An optimized mix containing hybrid fibres was produced through parametric research on the effects of varying fibre contents on the mechanical properties of the concrete structure, specifically the compressive strength, shear strength, and toughness. The mechanical qualities of the concrete construction were shown to benefit from these modifications. Additionally, it was shown that when utilizing various fibre compositions, the combination of glass and polypropylene fibre produces the best outcomes in terms of compressive strength and toughness. Hybrid fibres were added to the concrete mix at various ratios, but they didn’t replace any other ingredients from the M30 mix designs. In this investigation, different amounts of fiber-containing cement (0.5%, 1%, 1.5%, and 2%) were added and tested individually in a compression testing machine with a 2000-ton capacity after 7 and 28 days of curing. The readings were taken to determine the optimal percentage of fibers to add to concrete, aiming to increase the concrete’s compressive strength significantly. Additionally, research has been conducted to determine how different types of fibre affect the mechanical properties of concrete structures. It also helps to understand the effect of age on concrete structures. Additional comparisons between various destructive and non-destructive tests have been conducted, and a correlation has been established between the two types of examinations.

Researchers investigate alternative materials for concrete production because of rising market need for sustainable cost-efficient building materials. Marble dust serves as a suitable alternative in concrete applications since it originates from the marble industry while creating environmental waste management hurdles. This study examines marble dust integration into concrete mixes through investigations into concrete mechanical properties, which change when marble dust proportion varies. This study identifies the optimal level of marble dust substitution that enhances strength development, improves resistance properties and maintains adequate workability. The research used concrete specimens containing various quantities of marble dust to replace cement according to weight ratios between 0% to 20%. Standards tests assessed the mechanical behavior of modified concrete through measurements of compressive strength in addition to split tensile strength evaluations. The test outcomes showed that marble dust implementations impact concrete strength properties in both compressive and split tensile aspects. The compressive strength and split tensile strength of concrete mixtures improved with marble dust content up to 16%, primarily due to the filler effect and enhanced particle distribution within the cement matrix. However, replacement levels reaching up to 20% resulted in a decline in strength, as the reduction in cementitious components limited effective participation in the hydration process. Studies indicate that moderate replacement of cement with marble dust not only enhances concrete properties but also reduces environmental impact by lowering cement consumption. The construction industry benefits from this sustainable substitution, as the use of marble dust helps minimize waste generation and promotes eco-friendly practice.

This study investigates the corrosion resistance of zinc-PVDF-graphene (zinc-PVDF-G) coatings on mild steel substrates. Coatings with varying graphene concentrations were prepared using electrochemical deposition for zinc, followed by brush coating of PVDF-graphene. Central composite design (CCD) of response surface methodology (RSM) was employed to optimise the coating composition, and high R2 values confirmed the reliability of the models. Characterisation using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transmission spectroscopy (FTIR) demonstrated uniform coating morphology and strong adhesion. The inclusion of 0.9% graphene in PVDF significantly enhanced corrosion resistance, with the P3-coated sample achieving a barrier performance of 5.24 × 106 Ω·cm2, an OCP of −0.563 V, and a protection efficiency that improved by approximately 61.6% compared to graphene-free coatings. These results indicate that graphene effectively reinforces the PVDF matrix, reduces diffusion of corrosive species, and provides superior long-term stability, demonstrating the potential of zinc–PVDF-G coatings for high-performance corrosion protection.

The most widely used building material in the world is conventional concrete having high carbon footprint and highly dependent on natural resources. To overcome these challenges the present study focuses on the designing and assessing the performance of low-carbon concrete mixes using fly ash (FA), ground granulated blast furnace slag (GGBS) and graphene oxide (GO), various tests were performed to investigate the mechanical properties, microstructural characteristics and sustainable assessment of the developed mixes. Response surface methodology (RSM) was used to design the mixes incorporating 20% FA, varying GGBS (5-15%) and GO (0.02-0.08%). Among the developed mixes, mix with 15% GGBS and 0.05% GO an improvement was observed with an increase of 25.55%, 19.37%, 15.95% and 10.76% for compressive strength, flexural strength, modulus of elasticity and poisson's ratio respectively compared to control mix although addition of GO reduced slump of concrete mixes. FESEM images supported the experimental findings with dense microstructure of mixes with GGBS and GO. Models developed through RSM possessed high R2 values and analysis of variance (ANOVA) confirmed significance of the developed models and reliability of the prediction. Sustainability assessment was carried out to evaluate embodied carbon, eco strength index and carbon footprint reduction and it indicated a 28% reduction in embodied carbon for the mix containing 20% FA, 15% GGBFS and 0.02% GO compared with the control mix, highlighting the potential of these materials in producing low-carbon concrete.

The management of the production and post-use waste disposal from rubber-based materials production or rubber waste has been a concern as it might negatively impact the environment, e.g. water and soil pollution. Henceforth, this study investigates the feasibility of utilizing rubber waste in compressed rubberized bricks. This study discusses the source of rubber waste and the design parameters for the mix ratio of compressed bricks and rubber waste. Compressive strength and water absorption were observed to examine the behaviour of the compressed bricks.

Currently, the field of structural health monitoring (SHM) is focused on investigating non-destructive evaluation techniques for the identification of damages in concrete structures. Magnetic sensing has particularly gained attention among the innovative non-destructive evaluation techniques. Recently, the embedded magnetic shape memory alloy (MSMA) wire has been introduced for the evaluation of cracks in concrete components through magnetic sensing techniques while providing reinforcement as well. However, the available research in this regard is very scarce. This study has focused on the analyses of parameters affecting the magnetic sensing capability of embedded MSMA wire for crack detection in concrete beams. The response surface methodology (RSM) and artificial neural network (ANN) models have been used to analyse the magnetic sensing parameters for the first time. The models were trained using the experimental data obtained through literature. The models aimed to predict the alteration in magnetic flux created by a concrete beam that has a 1 mm wide embedded MSMA wire after experiencing a fracture or crack. The results showed that the change in magnetic flux was affected by the position of the wire and the position of the crack with respect to the position of the magnet in the concrete beam. RSM optimisation results showed that maximum change in magnetic flux was obtained when the wire was placed at a depth of 17.5 mm from the top surface of the concrete beam, and a crack was present at an axial distance of 8.50 mm from the permanent magnet. The change in magnetic flux was 9.50 % considering the aforementioned parameters. However, the ANN prediction results showed that the optimal wire and crack position were 10 mm and 1.1 mm, respectively. The results suggested that a larger beam requires a larger diameter of MSMA wire or multiple sensors and magnets for crack detection in concrete beams.

Offshore structures like oil pipelines and concrete mattresses are constantly exposed to adverse environmental effects such as saline water infiltration, fisherman trawl, buoyancy effects and vibrations from sea waves. As a result, the deterioration and corrosion of structures in such an environment are often a major concern. Hence there is the need for developing environmentally friendly high-density concrete for potential application in offshore activities as well as mitigating some of the challenges of concrete in harsh environments. Against this backdrop, environmentally friendly high-density concrete was developed by partially substituting cement with fly ash and adding graphene oxide. Whereas the coarse aggregate content of the concrete was fully replaced with coated waste steel punching collected from construction sites. The dosage of fly ash varied from 20 to 50