Search Results (412)

Porous concrete is widely recognized as an eco-friendly pavement material; however, existing studies mainly focus on its use as a base course, and systematic investigations on porous concrete specifically designed for heavy-traffic pavements and multifunctional surface performance remain limited. In this study, a novel multifunctional porous concrete with integrated noise reduction and drainage performance (PCNRD) was developed as a top-layer pavement material, addressing the performance gap in current applications. A comprehensive evaluation of the surface properties of porous concrete was performed based on tests of the sound absorption, void ratio, permeability, and wear resistance. The results demonstrate that the porous concrete exhibits excellent sound absorption (sound absorption coefficient 0.22–0.35) and high permeability (permeability coefficient 0.63–1.13 cm/s), and superior abrasion resistance (abrasion loss ≤ 20%) within an optimized porosity range of 17–23%. Furthermore, an optimized pavement thickness (8–10 cm) was proposed, and functional correlations among key surface performance indicators were revealed for the first time. Based on a uniform experimental design, four key mix parameters (water–cement ratio, cement content, silica fume content, and cement strength grade) were examined using strength and effective porosity as dual control indices, leading to the development of a novel mix design method tailored for PCNRD. This study not only fills the technical gap in high-performance porous concrete for heavy-traffic pavement surfaces but also provides a practical scientific framework for its broader engineering application. Full article

This study explores a sustainable strategy for enhancing high-strength concrete (HSC) by partially replacing natural fine aggregates with stone quarry sludge (SQS), a byproduct of quarrying operations. The aim is to promote environmental conservation and waste valorization while maintaining or improving concrete performance. Concrete mixes were prepared by substituting fine sand with SQS at incremental levels of 10%, 20%, 30%, 40%, and 50%. Mechanical properties were assessed through specific weight measurements, compressive strength tests, and three-point bending evaluations. FTIR analysis was conducted to investigate microstructural changes, and a carbon footprint assessment was performed to quantify environmental benefits. The mix containing 20% SQS exhibited optimal performance, achieving a compressive strength of 61 MPa and a bending strength of 5.1 MPa. FTIR results confirmed enhanced C–S–H gel formation, indicating improved microstructural integrity. Carbon footprint analysis revealed that moderate SQS substitution significantly reduces embodied carbon. These findings support the use of quarry sludge as a viable component in eco-friendly HSC, with potential for further optimization and long-term durability studies. Full article

Accurate prediction of compressive strength in eco-friendly concretes, where part of the cement is replaced with recycled glass powder, remains a fundamental challenge for sustainable construction. This study evaluates and compares the performance of five machine learning models—Naïve Bayes, Random Forest, Decision Tree, Support Vector Machine (SVM), and k-Nearest Neighbors (k-NN)—for classifying the compressive strength of concretes with different mix designs and curing ages. The dataset includes 846 experimental samples produced at the School of Civil Engineering of UPM between 2004 and 2019. The results showed that Naïve Bayes and Random Forest achieved the highest accuracy and generalizability, confirming that the incorporation of glass powder does not introduce significant data instability and can serve as a viable and sustainable substitute of cement. The Decision Tree model provided the greatest interpretability, enabling insight into the influence of mixture parameters, while SVM and k-NN were primarily effective in extreme strength categories. Overall, the findings demonstrated that probabilistic and ensemble learning methods outperform deterministic and proximity-based algorithms in classifying materials with high compositional variability. This work reinforces the potential of artificial intelligence as a non-destructive, reliable, and scalable tool for optimizing the performance of low carbon concretes and promoting sustainable materials engineering. Full article

The present experimental study was set up to examine the use of waste seashells (ground to powder form) to replace cement partially and as a filler material in concrete. Two distinct particle size ranges of seashell powder were adopted based on their intended function: 63–125 micron particles are used as a filler to enhance packing density, and 0–63 micron particles are used as a cement replacement to improve reactivity. Four concrete mixes, including a control mix, were designed, with ground seashell powder used to replace cement, both as a filler replacing 15% of the cement and additionally as finer seashell powder replacing 0, 15, and 30% of cement (labelled S0F15, S15F15, and S30F15, respectively). The seashells’ chemical, physical, and mineralogical properties were characterised using particle size analysis through sieving, X-ray diffraction (XRD), Scanning Electron microscopy (SEM), and pH test methods. Furthermore, the fresh properties of concrete, such as initial and final setting time, were studied. The hardened seashell-based concrete was subjected to direct compressive strength, bulk density, and modulus of elasticity analysis. The results showed that the 28-day compressive strength of concrete with seashells was moderately reduced by nearly 25% compared to the control mix. In the case of modulus of elasticity, the reductions were about 5%, 7% and 13% for mixes S0F15, S15F15 and S30F15, respectively, compared to the control mix CM. Finally, the carbon emission from concrete with 15% and 30% seashell powder content as cement replacement (plus 15% cement replaced with the powder acting as a filler in both cases) resulted in a notably lower carbon emission of 250 and 212 kg CO₂ e/m³, respectively, compared to the control mix, with a reduction of approximately 24%. This is a sizable reduction in Global Warming Potential (GWP) value. Therefore, the study concluded that the investigated seashell powder in concrete could benefit an eco-friendly environment and conservation of natural resources. Full article

This study employs a practice-oriented research method, emphasizing practical application rather than laboratory testing, and was conducted in Pingtung County, Taiwan, from 2017 to 2023. The practical results of the five case studies demonstrate that (1) eco-friendly buildings integrating agricultural and fishery waste overcome the obstacles of obtaining building permits and (2) the carbon emissions of exterior walls made of pozzolana are only 44% of those of reinforced concrete. This study contributes to understanding the contemporary characteristics of sustainable buildings and provides directly applicable insights into and suggestions on how buildings can actively utilize local materials. Full article

This study investigates the mechanical and durability performance of sustainable concrete using stone dust (SD) and ground sugarcane bagasse ash (GSCBA) to partially replace natural sand and cement, respectively. The experimental program was conducted with concrete containing 0–40 wt% GSCBA and 100% SD were prepared and tested. The results showed that full replacement of natural sand with SD did not significantly affect compressive strength. Concrete containing 10% GSCBA and 100% SD (10GSCBA) exhibited comparable compressive strength to the control concrete (CON) up to 90 days. However, the modulus of elasticity and modulus of rupture decreased slightly with increasing GSCBA content, indicating a close correlation with compressive strength. The mix containing 40% GSCBA and 100% SD (40GSCBA) achieved a compressive strength of 42.6 MPa at 90 days, representing 91% of the CON, with acceptable durability performance. These findings demonstrate that the combined utilization of SD and GSCBA offers an innovative and eco-efficient solution for concrete production, contributing to reduced cement consumption, lower production costs, and minimized carbon emissions without necessarily affecting mechanical strength or the long-term viability of the system. Full article

The incorporation of agricultural waste into construction materials represents a promising pathway toward achieving carbon neutrality in the building sector. This study investigates the flexural performance of a novel prefabricated external wall panel composed of corn straw concrete (CSC), an eco-friendly composite material that utilizes waste corn straws. While prior studies have explored rice straw and hemp fiber concrete, they primarily focused on the mechanical properties of these materials rather than the design of prefabricated panels. This study fills the gap by optimizing reinforcement ratio and window opening layout for CSC panels, and validating their structural viability for prefabricated enclosures. An optimal mix proportion was identified, which meets the mechanical requirements for non-load-bearing applications. Four prototype panel specimens were subjected to out-of-plane monotonic loading, considering variables including reinforcement ratio (0.18% vs. 0.24%) and the presence of a window opening (25% area ratio). Results indicated that increasing the reinforcement ratio significantly enhanced the ultimate load capacity by up to 33.3% (from 45 kN to 60 kN)—an enhancement effect that was 12–15% higher than that of reported rice straw concrete. In contrast, the introduction of an opening reduced the ultimate load capacity by 11.1–16.7%. A detailed nonlinear finite element model (FEM) was developed and validated against experimental results. The validation results indicated deflection error of 7.7–12.8% (mean: 9.33%; SD: 2.05), ultimate load error of 7.7–11.1% (mean: 9.48%; SD: 1.32), and a correlation coefficient (R²) of 0.96 between simulated and experimental values. Furthermore, analytical methods for predicting the cracking moment (with an average error of 5.97%) and ultimate flexural capacity, based on yield line theory (with an average error of 8.43%), were proposed and verified. This study demonstrates the structural viability of CSC panels and provides a sustainable solution for waste reduction in prefabricated building enclosures, contributing to greener construction practices. Full article

The production of concrete strongly influences the environment. It is a versatile and sustainable construction material capable of creating a wide range of structures. It has always been indispensable as a material for the engineering and construction industry, including applications in hydraulic structures (e.g., dams, underwater tunnels, sluices, and other concrete structures), where mass concrete is a fundamental material in the construction industry. Developing sustainable concrete as an alternative construction material to the traditional one provides a reduction in the carbon dioxide footprint with regard to cement use and waste material disposal in landfills. This paper provides a comprehensive review of current trends and opportunities in sustainable construction using mass concrete. It underscores the importance of incorporating eco-friendly practices to mitigate environmental impact by using by-products as green materials. The review highlights how optimizing clinker content, supplementary cementitious materials (SCMs), and aggregates can improve the strength, durability, and thermal stability of mass concrete. Strategic material selection helps minimize thermal cracking, extend service life, and reduce environmental impact. Future research should focus on developing advanced mix design strategies and standardized practices for sustainable infrastructure. Full article

In the last decades, composite materials made of synthetic fibers embedded in organic or inorganic matrices have been successfully used for strengthening reinforced-concrete and masonry buildings. The scientific community is currently discussing the low sustainability of these materials and their environmental impact due to the production process, the life cycle, and the generation of potentially harmful waste. In this context, the use of natural textiles represents a promising solution, alternative to conventional synthetic fibers, aimed at designing an innovative composite material obtained from renewable resources with no energy consumption and greatly reducing the impact of building activities on the environment. In this paper, an experimental assessment of ten different natural textiles is presented in order to compare their mechanical properties for possible use in innovative, eco-friendly composite materials. Mechanical tensile tests were performed on the ten different textiles before and after an all-natural protective treatment referred to as the “hornification” process. Treatment-induced changes in the fiber morphology were also analyzed using a scanning electron microscope (SEM), which provided high-resolution images of the surface and cross-sectional area of the fibers. Considering that the current demand for sustainable building materials capable of ensuring a greener future for the construction industry is on the rise, the promising results obtained in this study could be useful to the academic community and building industry. Full article

Cold-bonded (CB) fly ash aggregate, an eco-friendly material derived from industrial by-products, is used to fully replace natural coarse aggregate in producing lightweight concrete (LWC-CB). This study systematically investigates the post-high-temperature mechanical properties and damage mechanisms of LWC-CB. Specimens exposed to ambient temperature (10 °C) and elevated temperatures (200 °C, 400 °C, 600 °C) underwent cubic compression tests, with surface deformation monitored via digital image correlation (DIC). Experimental results indicate that the strength retention of LWC-CB is approximately 6% superior to ordinary concrete below 500 °C, beyond which its performance converges. Damage analysis reveals a transition in failure mode: at ambient temperature, shear failure is governed by the low intrinsic strength of CB aggregates, while after high-temperature exposure, damage localizes within the mortar and the interfacial transition zone (ITZ) due to mortar micro-cracking and thermal mismatch. To elucidate these mechanisms, a three-dimensional mesoscale model was developed and validated, effectively characterizing the internal multiphase structure at room temperature. Furthermore, a homogenization model was established to analyze the macroscopic thermo-mechanical response. The numerical simulations show strong agreement with experimental data, with a maximum deviation of 15% at 10 °C and 3% after high-temperature exposure, confirming the model’s accuracy in capturing the performance evolution of LWC-CB. Full article

The sustainable management of winery residues could represent a cornerstone for promoting environmental and economic sustainability from a circular economy perspective. In this context, our study aimed to evaluate Vitis vinifera L. ‘Nero di Troia’ cultivar grape pomace as a valuable waste product for the cultivation of Pleurotus mushroom, in comparison with traditional wheat straw-based cultivation. Mushroom extracts were prepared through the eco-friendly microwave-assisted extraction technique, using green solvents with different polarity degrees. Total protein content, total polyphenol content, and antioxidant activity (FRAP and DPPH assays) were assessed for the water and EtOH hydrophilic extracts. Grape pomace often gave higher values than wheat straw, especially for the P. eryngii var. eryngii water extract protein content, which was 3.5-fold higher (0.68 ± 0.14 mg BSA/mL and 0.192 ± 0.025 mg BSA/mL, respectively). The ethyl acetate extracts of both mushroom species gave biologically relevant results in terms of inhibiting activity against acetylcholinesterase, an enzyme involved in the pathogenesis of Alzheimer’s disease (50% inhibitory activity at concentrations ≤ 1.5 mg/mL), thus paving the way for more in-depth investigation. The extract’s metabolic profile was investigated through GC-MS analysis. The results show that incorporating grape pomace into mushroom production represents a concrete step toward more sustainable biotechnological processes. Full article

This study presents a comprehensive strategy for mitigating drying shrinkage of alkali-activated slag mortar (AASM) with the high-dosage incorporation of waste concrete powder (WCP). Response surface methodology (RSM) coupled with microstructural analysis is used to investigate the synergistic effects of WCP particle size (R), activator modulus (AM), activator content (AC), and water to solid ratio (W/S) on shrinkage behavior and matrix development. The optimized mix—WCP-R = 33.6 µm, AM = 1.23, AC = 6.03%. and W/S = 0.49—exhibits a 120-day drying shrinkage of only 1450.1 µε, significantly lower than that of conventional AASM. Microstructural observations reveal that coarser WCP particles act predominantly as fillers, enhancing stability, whereas finer particles promote gel formation but increase shrinkage. A high AM (1.6) refines the pore structure by reducing large pores (>0.05 µm), while a low W/S (0.46) decreases total porosity to 7.67%, collectively restricting moisture transport. The coexistence of C-(A)-S-H gel and hydrotalcite improves matrix integrity. Notably, this optimized HWAASM achieves a substantially reduced carbon footprint of 180 kg CO₂-eq/t, underscoring its significant environmental advantage. The findings advance the understanding of shrinkage mechanisms in high-WCP-AASM and offer an eco-friendly route for valorizing construction waste and developing low-carbon building materials. Full article

In response to the issues of microcrack susceptibility, high brittleness, and unstable mechanical properties of desert sand recycled aggregate concrete (DSRAC), this study experimentally investigated the mechanical performance of DSRAC reinforced with hybrid steel–FERRO fibers. By testing macroscopic properties (compressive, splitting tensile, and flexural strengths) under different desert sand replacement ratios and fiber dosages, combined with microscopic analysis, the fiber-matrix interfacial behavior and toughening mechanism were clarified. The results showed that (1) DSRAC achieved optimal compressive strength when desert sand replaced 30% natural sand, with an obvious early strength enhancement; (2) both steel fibers and FERRO fibers independently improved DSRAC’s mechanical properties, while their hybrid combination (especially F0.15-S0.5 group) exhibited a superior synergistic strengthening effect, significantly outperforming single-fiber groups; (3) the established constitutive model accurately described the stress–strain response of hybrid fiber-reinforced DSRAC; (4) microscopic observations confirmed fibers inhibited crack propagation via bridging and stress dispersion, with hybrid fibers exerting multi-scale synergistic effects. This study provided theoretical–technical support for resource utilization of desert sand and recycled aggregates, and offered practical references for localized infrastructure materials (e.g., rural road subgrades and small-span culverts) in desert-rich regions and high-value reuse of construction waste in prefabricated components, advancing eco-friendly concrete in sustainable construction. Full article

In Turkey, flexible pavement containing bituminous material is widely preferred on highways. Rigid pavement, which is based on concrete, is generally used in small-scale, specific projects. This situation, which has arisen due to historical and technical reasons, has also brought with it certain prejudices against rigid pavement applications. A review of the literature reveals that many factors influence the choice of highway pavement type, but decision-makers tend to make their selection based on the most important factors, disregarding other parameters. The lack of a systematic factor analysis is a shortcoming in this regard. In this research, a combined multi-criteria decision-making study was conducted, including the neglected factors, to address this technical deficiency in the pavement type selection process. Through detailed analysis, parameters likely to influence pavement type selection were identified and analyzed using the hybrid AHP-TOPSIS approach, guided by the opinions of experts in the field. The analysis shows that comfort (user ride quality), financial, and environmental factors are the most effective main criteria, while maintenance and repair costs, eco-friendliness, and initial construction costs were identified as the most critical sub-criteria influencing the choice of pavement type. Based on the analysis results, a detailed decision support system was presented to decision-makers according to the characteristics of the alternatives obtained. The results highlight the need for decision-making frameworks that prioritize both long-term cost efficiency and user safety, contributing to more sustainable and resilient pavement applications. Full article

This study investigates the static mechanical behavior of a novel eco-friendly high-performance concrete (HPC) reinforced with fibers under different moisture conditions, reflecting the humidity variations commonly encountered in engineering practice. Three saturation levels—natural, dry, and water saturated—were considered. The optimal dosages of basalt and glass fibers were first identified through tests in the natural state, and empirical relationships between fiber volume fraction, compressive strength, and fracture energy were established. Comparative experiments were then conducted at the optimal dosages under varying saturation conditions. Results show that basalt fiber provides superior compressive strength, exceeding that of glass fiber by 0.86% in the dry state and 10.66% in the saturated state. Conversely, glass fiber exhibits a greater enhancement in flexural strength, with improvements of 14.91% and 3.38% over basalt fiber under dry and saturated conditions, respectively. Although preliminary models were proposed to correlate fiber volume fraction with strength in dry and saturated environments, their predictive accuracy proved limited. Overall, the findings highlight the distinct reinforcing effects of basalt and glass fibers on HPC under different moisture conditions, offering guidance for the design and application of fiber-reinforced recycled concrete in humid service environments. Full article