Search Results (968)

The increasing demand for sustainable construction materials has underscored the limitations of conventional interlocking paving blocks (IPBs), particularly regarding durability, mechanical performance, and environmental impact. To overcome these shortcomings, this study proposes an integrated strategy of incorporating various waste materials in the production of IPBs namely: Untreated and surface-treated crumb rubber (CR) as a partial sand replacement at levels of 10%, and 20%; ceramic powder (CP) and glass powder (GP) as cement partial replacement at levels of 10%, 20%, and 30%, recycled ceramic as a full replacement of dolomite; and discrete fibers (basalt, polypropylene, and glass). A series of experimental tests was conducted to assess the slump, compressive and flexural strengths, water absorption, abrasion resistance, and microstructure of the proposed IPBs. The results of this study revealed that while untreated CR reduced workability and strength, it enhanced flexural resistance. Surface treatments of CR using CP and GP improved bonding and reduced porosity, with 20% CP yielding the best performances of 17.3% and 20% increases in compressive and flexural strength, respectively. Among fibers, 0.6% basalt fiber offered optimal strength and abrasion resistance (0.20 mm), while 0.6% polypropylene fiber achieved the lowest water absorption (3.70%) and a minimum abrasion depth of 0.28 mm at TR20CP mix. Microstructure analyses confirmed denser microstructure and stronger interfacial bonding in treated and fiber-reinforced mixes. This work offers a scalable, waste-based enhancement strategy for producing more durable and sustainable production of IPBs. Full article

As manufacturing industries pursue net-zero emission (NZE) goals, hybrid manufacturing processes that integrate additive manufacturing (AM) with traditional casting techniques are gaining traction for their sustainability potential across the globe. Therefore, this work presents a “gate-to-gate” life cycle assessment (LCA) comparing AM-assisted sand casting (AM-SC) and AM-assisted investment casting (AM-IC), for Al-Si5-Cu3 alloy as a case material, under various energy scenarios including a conventional grid mix and renewable sources (wind, solar, hydro, and biomass). This study compares multiple environmental impact categories based on the CML 2001 methodology. The outcomes show that AM-SC consistently outperforms AM-IC in most impact categories. Under the grid mix scenario, AM-SC achieves 31.57% lower GWP, 19.28% lower AP, and 21.15% lower EP compared to AM-IC. AM-SC exhibits a 90.5% reduction in “Terrestrial Ecotoxicity Potential” and 75.73% in “Marine Ecotoxicity Potential”. Wind energy delivers the most significant emission reduction across both processes, reducing GWP by up to 98.3%, while AM-IC performs slightly better in HTP. These outcomes of the study offer site-specific empirical insights that support strategic decision-making for process selection and energy optimisation in casting. By quantifying environmental trade-offs aligned with India’s current energy mix and future renewable targets, the study provides a practical benchmark for tracking incremental gains toward the NZE goal. This work followed international standards (ISO 14040 and 14044), and the data were validated with both foundry records and field measurements; this study ensures reliable methods. The findings provide practical applications for making sustainable choices in the manufacturing process and show that the AM-assisted conventional manufacturing process is a promising route toward net-zero goals. Full article

The increasing demand for sustainable construction materials has prompted the recycling of construction and demolition waste in concrete manufacturing. This study investigates the feasibility of utilizing porcelain and brick waste as partial substitutes for natural sand in concrete with the objective of improving sustainability and preserving mechanical and durability characteristics. The experimental program was conducted in three consecutive phases. During the initial phase, natural sand was partially substituted with porcelain waste powder (PWP) and brick waste powder (BWP) in proportions of 25%, 50%, and 75% of the weight of the fine aggregate. During the second phase, polypropylene fibers were mixed at a dosage of 0.5% by volume fraction to enhance tensile and flexural properties. During the third phase, zinc oxide nanoparticles (ZnO-NPs) were utilized as a partial substitute for cement at concentrations of 0.5% and 1% to improve microstructure and strength progression. Concrete samples were tested at curing durations of 7, 28, and 91 days. The assessed qualities encompassed workability, density, water absorption, porosity, compressive strength, flexural strength, and splitting tensile strength. Microstructural characterization was conducted utilizing X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). The findings indicated that porcelain waste powder markedly surpassed brick waste powder in all mechanical and durability-related characteristics, particularly at 25% and 50% sand replacement ratios. The integration of polypropylene fibers enhanced fracture resistance and ductility. Moreover, the incorporation of zinc oxide nanoparticles improved hydration, optimized the pore structure, and resulted in significant enhancements in compressive and tensile strength throughout prolonged curing durations. The best results were obtained with a mix of 50% porcelain sand aggregate, 1% zinc oxide nanoparticles as cement replacement, and 0.5% polypropylene fibers, for which the improvements in compressive strength, flexural strength, and splitting tensile strength were 39.5%, 46.2%, and 60%, respectively, at 28 days. The results confirm the feasibility of using porcelain and brick waste as sand replacements in concrete, as well as polypropylene fiber-reinforced concrete and polypropylene fiber-reinforced concrete mixed with zinc oxide nanoparticles as a sustainable option for construction purposes. Full article

To address the challenges of high impurity content and low whiteness in quartz sand, this study proposes a combined process of solid-state chlorination roasting followed by acid leaching. By using calcium chloride (CaCl₂), a safe and low-cost solid chlorinating agent, mixed with quartz sand for chlorination rofasting, the process effectively removes key impurity elements such as aluminum (Al) and iron (Fe), thereby enhancing the whiteness of the quartz sand. The quartz sand used in the experiment had an aluminum content of 4519 ppm and an iron content of 496.3 ppm. Under optimized conditions—a mass ratio of quartz sand to CaCl₂ of 1:0.1, a roasting time of 2 h, and a roasting temperature of 1100 °C—the contents of aluminum and iron impurities were reduced to 422.62 ppm and 124.43 ppm, respectively, although the calcium content increased significantly. Subsequent acid leaching further reduced the residual impurities and the introduced calcium elements. The results demonstrate that the combined process achieved removal rates of 91.1% for aluminum, 90.7% for iron, and 50.2% for calcium, while increasing the whiteness to 85.2 Wb. This approach exhibits significant advantages compared to standalone acid leaching or chlorination roasting. This approach exhibits significant advantages compared to standalone acid leaching or chlorination roasting, thus offering a viable technical route for the production of high-quality panel-grade quartz sand. Full article

This study presents a sustainable and time-efficient method for producing aerated lightweight concrete (ALC) by addressing two key challenges: long drying times and limited high-silica sand. The proposed approach combines rapid drying, reducing curing time from 24–48 h to less than one hour, with recycled glass powder to enrich locally available silica-poor sand. The concrete mixtures were characterized using scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS), along with experimentally determined key parameters such as compressive strength, dry density, porosity, and thermal conductivity. Comparative testing was conducted using sand samples from the UAE and UK to represent contrasting climatic and geological conditions, silica-poor desert versus silica-rich quartz, to evaluate adaptability and performance. Two mixes were tested: untreated and glass enriched. The modified mix achieved higher compressive strength, better thermal insulation, and lower environmental impact, while rapid drying maintained structural integrity. The method offers a scalable, low-carbon solution aligned with circular economic principles. Full article

Geopolymers are inorganic aluminosilicate binders formed by alkali activation of reactive powders, offering a sustainable, low-carbon alternative to Portland cement. Their rapid setting and chemical durability make them well-suited for additive manufacturing (AM) in demanding environments, including underwater construction, where chemical stability is essential for both structural integrity and environmental safety. This study evaluates two metakaolin-based formulations designed for underwater extrusion, differing in activator chemistry and rheology control. Standardized leaching tests revealed alkaline but stable leachates with strong immobilization of most ions; major anions and total dissolved solids remained within regulatory thresholds. Limited exceedances were observed—soluble organic carbon in the NaOH-activated mix and arsenic/selenium in the waterglass–sand system—highlighting specific areas for mix improvement rather than fundamental limitations of the material. Complementary radioactivity screening confirmed activity concentration indices well below the regulatory limit, with measured radionuclide activities falling comfortably within exemption ranges. Together, the leaching and radioactivity results demonstrate that both formulations provide robust matrix integrity and environmental compatibility, while highlighting clear opportunities for mix design improvements to further minimize ecological risks. Full article

This systematic review applies the PRISMA methodology (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) to evaluate the use of recycled sand, obtained from construction and demolition waste (CDW), in mortars for civil construction. A total of 24 studies published between 2020 and 2025 were analyzed, retrieved from the Scopus and Web of Science databases. The main objective is to assess the technical feasibility and environmental benefits of recycled sand in mortars, while addressing research gaps such as the lack of standardized methodologies and the limited understanding of durability at higher replacement levels. Given the significant resource consumption and waste generation in the construction sector, the study highlights emerging trends in adopting recycled sand as a sustainable alternative to natural aggregates. Findings indicate that optimal replacement levels range between 30 and 50% in ordinary Portland cement (OPC) mortars, and up to 100% in geopolymer mixtures when appropriate processing and activation methods are applied, without compromising mechanical performance. Reported benefits include cost reduction, lower carbon footprint, and enhanced compactness. However, challenges such as higher porosity and the need for optimized mix designs, and high heterogeneity of CDW sources and processing methods remain. Overall, the review confirms that recycled sand is a technically viable and environmentally beneficial material for mortar production, though future research must focus on harmonizing test protocols and long-term performance evaluation. In addition, a bibliometric analysis was conducted to map scientific output on this topic, identifying key countries, journals, and publication trends. Full article

It is known that geopolymer mortar exhibits high compressive strength but relatively low flexural strength, high brittleness, and poor toughness. Engineering practices for cement-based materials have demonstrated that incorporating fibers can effectively prevent the expansion of existing cracks and the formation of new ones in the materials. Adding polypropylene fibers to geopolymer mortar can, on the one hand, improve the crack resistance of the mortar, and on the other hand, enhance the impact resistance of the geopolymer mortar. In this paper, slag, metakaolin, and fly ash are utilized as silico-aluminous raw materials, standard sand is employed as aggregate, and a mixture of water glass and NaOH in a specific proportion is used as the alkali activator to prepare geopolymer mortar. Polypropylene fibers are incorporated to improve its mechanical properties. The effects of fiber length and mixing method on the mechanical properties of geopolymer mortar are studied to determine the optimal fiber length and mixing method. The mechanism of the mechanical properties of fiber-reinforced geopolymer mortar is analyzed by combining SEM. The research results indicate that the geopolymer mortar with 15 mm single-doped fibers exhibits the best flexural strength and toughness. In contrast, the geopolymer mortar with 12 mm single-doped fibers demonstrates the best compressive strength. The geopolymer with 9 mm and 18 mm hybrid-doped fibers has the best mechanical properties and is superior to the geopolymer mortar with single-doped fibers. Full article

Enhancing interlayer bond strength remains a critical challenge in the extrusion-based 3D printing of cementitious materials. This study investigates the optimisation of interlayer bond strength in extrusion-based 3D-printed cementitious materials through a combined application of Response Surface Methodology (RSM) and Artificial Neural Networks (ANNs). Using a concise yet comprehensive dataset, RSM provided interpretable main effects, curvature, and interactions, while the ANN captured non-linearities beyond quadratic forms. Comparative analysis revealed that the RSM model achieved higher predictive accuracy ($R^2=0.95$) compared to the ANN model ($R^2=0.87$). Desirability-based optimisation confirmed the critical importance of minimising casting delays to mitigate interlayer weaknesses, with RSM suggesting a water-to-cement (W/C) ratio of approximately 0.45 and a minimal time gap of less than 5 min, while ANN predicted slightly lower optimal W/C values but with reduced reliability due to the limited dataset. Sensitivity analysis using partial dependence plots (PDPs) further highlighted that ordinary Portland cement (OPC) content and W/C ratio are the dominant factors, contributing approximately 2.0 and 1.8 MPa respectively to the variation in predicted bond strength, followed by superplasticiser dosage and silica content. Variables such as water content, viscosity-modifying agent, and time gap exhibited moderate influence, while sand and fibre content had marginal effects within the tested ranges. These results demonstrate that RSM provides robust predictive performance and interpretable optimisation guidance, while ANN offers flexible non-linear modelling but requires larger datasets to achieve stable generalisation. Integrating both methods offers a complementary pathway to advance mix design and process control strategies in 3D concrete printing. Full article

Lithium slag (LS), a solid waste generated during lithium smelting, exhibits significant potential for geopolymer preparation. However, the high shrinkage of lithium slag geopolymer mortar (LSGM) severely restricts its engineering application. Currently, research on the effects of mix proportions (GBFS-LS mass ratio, water–binder ratio, and binder–sand ratio) on LSGM’s shrinkage, and the correlation between shrinkage behavior and microstructures (pore structure and thermal behavior), remains insufficient. Additionally, there is a lack of targeted shrinkage prediction models for LSGM. To address these research gaps, this study systematically investigates the shrinkage characteristics of LSGM and develops a modified prediction model. Thermogravimetric analysis–differential thermal gravimetric analysis (TG-DTG) results show that a lower GBFS-LS ratio promotes the formation of dense sodium-alumino-silicate hydrate (N-A-S-H) gels. Meanwhile, mercury intrusion porosimetry (MIP) tests demonstrate that optimizing the water–binder ratio and binder–sand ratio refines the pore structure of LSGM, where the average pore size is reduced from 53.5 nm at a GBFS-LS ratio of 3 to 28.75 nm at a GBFS-LS ratio of 1.5.Quantitatively; compared with the group with a GBFS-LS ratio of 3, the 90-day shrinkage strain of the group with a GBFS-LS ratio of 1.5 decreases by 25.8%. When the water–binder ratio decreases from 0.57 to 0.27, the 90-day shrinkage strain reduces by 36.7%; in contrast, increasing the binder–sand ratio from 0.21 to 0.39 leads to a 39.8% increase in 90-day shrinkage strain. Based on the experimental data and the fundamental framework of the American Concrete Institute (ACI) model, this study introduces mix proportion influence coefficients and constructs a novel shrinkage prediction model tailored to LSGM. The coefficient of determination (R²) of the proposed model exceeds 0.98. This model provides a reliable quantitative tool for the mix proportion optimization and engineering application of LSGM. Full article

To address limitations such as cleaning difficulties or secondary contamination/damage of cultural relics caused by the uncontrollable diffusion of water/cleaning agent/dirty liquids during the cleaning process in traditional cleaning methods, this study, using cotton textiles as an example, systematically investigated the cleaning efficacy of four in situ methods (blank gel, cleaning gel, ultrasonic emulsification, and gel + ultrasonic emulsification synergistic cleaning) on eight types of stains, including sand, clay, rust, blood, ink, oil, and mixed solid/liquid stains. Building upon this, this study proposed an efficient, targeted, in situ, and controllable cleaning strategy tailored for fragile, stained textile relics. Results demonstrated that, regardless of the stain type, the synergistic cleaning method of G+U (gel poultice + ultrasonic emulsification) consistently outperformed the cleaning methods of blank gel poultice, cleaning gel poultice, and ultrasonic emulsification. Furthermore, the gel loaded with cleaning agents was always more effective than the blank gel (unloaded cleaning agents). The poultice methods of blank gel and cleaning gel were better suited for solid stains, while the ultrasonic emulsification cleaning method was more effective for liquid stains. Meanwhile, it was also found that the optimal cleaning method proposed in this study (the G+U synergistic cleaning method) was a cleaning method that restricted the cleaning agent within the gel network/emulsion system, and utilized the porous network physical structure of gel, the chemical action of emulsion’s wetting/dissolving dirt, and the cavitation synergistic effect of ultrasound to achieve the targeted removal of contaminants from relics’ surfaces. Crucially, the cleaning process of G+U also had the characteristics of controlling the cleaning area at the designated position and effectively regulating the diffusion rate of the cleaning solution within the treatment zone, as well as the reaction intensity. Therefore, the proposed optimal (the synergistic cleaning method of G+U) cleaning method conforms to the significant implementation of the “minimal intervention and maximal preservation” principle in modern cultural heritage conservation. Consequently, the synergistic cleaning method of G+U holds promise for practical application in artifact cleaning work. Full article

Atmospheric corrosion in sand dust environments is driven by deposits that bear chloride, which sustain thin electrolyte layers on metal surfaces. We established a laboratory protocol to replicate this by extracting, formulating, and depositing a preliminary layer of mixed salts from natural dust onto samples, with humidity precisely set using the salt’s deliquescence behavior. Degradation was tracked with SEM/EDS, 3D profilometry, XRD, and electrochemical analysis. Bare steel showed progressive yet decelerating attack as rust evolved from discrete islands to a lamellar network; while this densification limited transport, its internal cracks and interfacial gaps trapped chlorides, sustaining activity beneath the rust. In contrast, QPQ-treated steel remained largely protected, with damage localized at coating defects as raised rust nodules, while intact regions maintained low electrochemical activity. By coupling salt chemistries derived from the field with humidity control guided by deliquescence and diagnostics across multiple scales, this study provides a reproducible laboratory pathway to predict atmospheric corrosion. Full article

In underground mine roadways, enlarged cross-sections have led to escalating surrounding rock stress, resulting in frequent support failures, elevated accident risk, and increased maintenance costs. However, the potential of fiber reinforcement to improve shotcrete under these high-stress conditions remains under-investigated. To address these issues, this study developed a novel fiber-reinforced cement-based composite using field construction-grade washed sand. The effects of binder-to-material ratios, fiber types (polyvinyl alcohol (PVA), polypropylene (PP), and basalt (BF)), and fiber dosages (1%, 2%, and 3%) were systematically investigated under uniaxial tension, uniaxial compression, and variable-angle shear. Based on the experimental results, an optimal mix formulation was determined via orthogonal experimental design to meet mining operational requirements. The findings demonstrate that fiber incorporation significantly enhances mechanical performance. Notably, PP fiber reinforcement increased the tensile strength by up to 675%, while BF fibers improved compressive strength by up to 198.5%, relative to unreinforced shotcrete. This study provides a theoretical foundation for optimizing fiber-reinforced shotcrete mix designs for mining and offers technical insights for field applications. Full article

One-part geopolymers (OPG) offer a low-carbon alternative to Portland cement, yet mix design remains largely empirical. This study couples machine learning with SHAP (Shapley Additive Explanations) to quantify how mix and curing factors govern performance in Ca-containing OPG. We trained six regressors—Random Forest, ExtraTrees, SVR, Ridge, KNN, and XGBoost—on a compiled dataset and selected XGBoost as the primary model based on prediction accuracy. Models were built separately for four targets: compressive strength at 3, 7, 14, and 28 days. SHAP analysis reveals four dominant variables across targets—Slag, Na₂O, Ms, and the water-to-binder ratio (w/b)—while the sand-to-binder ratio (s/b), temperature, and humidity are secondary within the tested ranges. Strength evolution follows a reaction–densification logic: at 3 days, Slag dominates as Ca accelerates C–(N)–A–S–H formation; at 7–14 days, Na₂O leads as alkalinity/soluble silicate controls dissolution–gelation; by 28 days, Slag and Na₂O jointly set the strength ceiling, with w/b continuously regulating porosity. Interactions are strongest for Slag × Na₂O (Ca–alkalinity synergy). These results provide actionable guidance: prioritize Slag and Na₂O while controlling w/b for strength. The XGBoost+SHAP workflow offers transparent, data-driven decision support for OPG mix optimization and can be extended with broader datasets and formal validation to enhance generalization. Full article

Conventional ridging and mulching machines struggle to perform effectively in yellow sand substrates due to their loose texture, high collapsibility, and strong fluidity, which compromise ridge stability and operational quality. To address these challenges, this study proposes the development of an integrated rotary tillage, ridging, and film-mulching machine specifically designed to meet the agronomic requirements of tomato cultivation in greenhouse environments with yellow sand substrate. Based on theoretical analysis and parameter calculations, a soil transportation model was established, and the key structural parameters—such as blade arrangement and helical shaft geometry—were determined. A discrete element method (DEM) simulation was employed to construct a contact model for the yellow sand–slag mixed substrate. A combination of single-factor experiments and Box–Behnken response surface methodology was used to investigate the effects of forward speed, shaft rotational speed, and tillage depth on ridge stability and operational performance. The simulation results indicated that a forward speed of 0.82 m·s⁻¹, shaft speed of 260 rpm, and tillage depth of 150 mm yielded the highest ridge stability, with an average of 95.7%. Field trials demonstrated that the ridge top width, base width, height, and spacing were 598.6 mm, 802.3 mm, 202.4 mm, and 1002.8 mm, respectively, with an average ridge stability of 94.3%, differing by only 1.4 percentage points from the simulated results. However, a quantitative traction/energy comparison with conventional equipment was not collected in this study, and we report this as a limitation. The energy consumption is estimated based on power usage and effective field capacity (EFC) under similar operating conditions. Soil firmness reached 152.1 kPa, fully satisfying the agronomic requirements for tomato cultivation. The proposed machine significantly improves operational adaptability and ridge stability in yellow sand substrate conditions, providing robust equipment support for efficient greenhouse farming. Full article