Search Results (864)

The recycling of waste clay bricks as raw materials for cement-based materials presents an effective solution to ecological pollution and resource shortages. Previous research has separately examined the effects of recycled brick fine aggregate and recycled brick powder on mortar or concrete, but few studies have investigated their combined use. This study aims to clarify the synergistic effect of recycled brick fine aggregate (RBA) and recycled brick powder (RBP) on mortar performance, quantify the influence of the RBP substitution rate on hydration characteristics and microstructural evolution, and determine the optimal mix proportion and curing system for fully recycled brick mortar. Mortar was prepared using 100% RBA and RBP at substitution rates of 0%, 10%, 20%, and 30%. The physical properties, mechanical performance, and durability of the mortar were evaluated, alongside an analysis of its microstructural morphology, mineral composition, and pore structure. The results indicate that adding an appropriate amount of RBP helped maintain the flowability of the mortar. As the RBP substitution rate increased, the mortar strength generally decreased in the early stages, but long-term curing (≥90 days) effectively mitigated this decline. The inclusion of RBP improved chloride ion permeability, with the 20% substitution rate achieving a favorable balance between compressive strength, fluidity, and durability without significantly affecting carbonation resistance. Microstructural analysis revealed that RBP regulated the morphology of hydration products and optimized the pore structure of the mortar, while the mineral composition of hydration products was similar to that of natural mortar. These findings provide a theoretical basis and technical support for the high-value utilization of construction and demolition waste in cement-based materials. Full article

Global water scarcity has intensified over recent decades, with projections suggesting that nearly six billion people may face limited access to clean water by 2050. Water reuse has emerged as a viable strategy to alleviate pressure on freshwater resources, particularly for non-potable applications. However, safe implementation requires wastewater to be treated to meet fit-for-purpose quality standards established through regional and national regulatory frameworks. Despite high levels of basic sanitation coverage in high-income countries such as the United States, persistent gaps remain in affordable and equitable wastewater management, particularly in small and underserved communities. This review focused on current knowledge of sustainable low-cost materials, including plant-based, clay, and clay-based ceramics; animal-derived products; and industrial by-products, used to remove a broad range of contaminants, including heavy metals, dyes, nutrients, emerging contaminants, and pathogens, from wastewater. The mechanisms governing their performance, such as adsorption, coagulation–flocculation, and filtration, were examined alongside contaminant-specific performance. The review further highlights the emerging role of 3D printing in developing customizable, efficient, and scalable treatment units using low-cost or waste-derived materials. Life cycle assessment (LCA) studies were evaluated to highlight their role as a flexible framework for assessing environmental impacts across life-cycle stages and for guiding the selection of sustainable materials and treatment systems. Together, these perspectives provide a comprehensive foundation for developing decentralized, community-oriented wastewater treatment solutions that support safe and effective water reuse, especially in rural and small communities. Full article

The urban heat island effect is strongly linked to the use of dense mineral pavements with high thermal inertia and lacking passive heat dissipation mechanisms. This article evaluates the potential of evaporatively cooled concrete pavers, based on capillary action and evaporation by incorporating recycled, bio-based, and lightweight materials to develop functional porosity. Ten paver formulations were developed using natural or recycled sand, hemp fibers and shives, and lightweight aggregates. Compressive strength, density, capillary absorption, and thermal behavior were characterized. Tests were conducted outdoors in full sunlight over 48 h in comparison with reference urban materials. The results show that capillary action alone is insufficient to induce effective cooling. The raw recycled sand formulation exhibits high capillary absorption but reaches maximum temperatures of 43–44 °C, which may be due to its low interconnected porosity that limits evaporation. Conversely, formulations incorporating bio-based materials or lightweight aggregates showed a more favorable balance between water availability, reduced density, and surface cooling performance. Hemp-based pavers reach maximum temperatures of 38–40 °C, while those incorporating expanded clay range between 37 and 39 °C, representing a reduction of 7 to 13 °C compared to bitumen and maintaining mechanical strengths suitable for pedestrian use. The results suggest that effective evaporative cooling is associated with sufficient capillary absorption, efficient water transfer toward the surface, and moderate density limiting heat storage. This study demonstrates that high capillary absorption alone does not ensure effective evaporative cooling. By systematically comparing recycled, bio-based and lightweight aggregates, the results reveal that evaporative cooling efficiency probably depends on the functional connectivity of the pore network and on a moderate material density limiting heat storage. Full article

Background/Objectives: The growing prevalence of obesity necessitates innovative gut-targeted material strategies to modulate diet-associated metabolic dysfunction. This study investigates a spray-dried konjac glucomannan–montmorillonite (KGM-MMT) hybrid designed to integrate fermentable polysaccharide properties with luminal lipid-adsorptive clay functions within a single micro-engineered formulation. Methods: In HFD-fed mice treated for 42 days with 2% w/w KGM-MMT, cumulative body weight gain was attenuated by 7.6%, with an AUC of 5094 ± 52.95, compared to 5513 ± 81.35 in HFD controls (p < 0.0001). Results: Serum IL-6 concentrations were reduced by 97% (p = 0.0002), while blood glucose decreased by 46% (p < 0.0001); these effects were greater than those observed with MMT (24%, p = 0.0271) and KGM (16%, ns). Gut microbiota profiling demonstrated a significant 6.2-log₂-fold increase in Lactobacillaceae (p = 0.023) and a 2.4-log₂-fold increase in Enterococcaceae (p = 0.015) following KGM-MMT treatment. Functional shifts inferred from 16S rRNA gene-based prediction indicated a 1.9-fold increase in short-chain fatty acid-related pathways and a 5.4-fold increase in bile acid deconjugation pathways. Conclusions: Although the KGM-MMT hybrid did not consistently outperform its individual components across all endpoints, it consolidated complementary KGM- and MMT-associated effects within a single dosage form. These findings support spray-dried KGM-MMT as a gut-targeted biomaterial strategy that integrates multiple luminal and microbiota-associated functions within a single formulation. Future studies should define dose–response relationships, validate microbiota-derived functional predictions using higher-resolution approaches, and assess durability and safety under longer-term exposure. Full article

Cement production accounts for approximately 8% of global CO₂ emissions, and while calcined clays have attracted growing attention as supplementary cementitious materials, the literature remains fragmented across clay types and performance metrics, with no unified comparative framework examining how mineralogical composition and calcination conditions jointly govern pozzolanic reactivity and downstream performance outcomes. This study addresses that gap through a PRISMA-guided systematic review of 32 peer-reviewed studies, validated by structured expert interviews, and a comparative assessment of five calcined clay categories: metakaolin (MK), limestone-calcined clay blends (LC³), illite-rich clays, montmorillonite (MM)- based clays, and ceramic waste (CW)- derived clays. Findings establish clear performance hierarchies with direct implications for the construction sector. MK at 10–15% cement replacement delivers compressive strength gains of 8–36%, chloride permeability reductions of 61–87%, and sulphate expansion reductions of up to 89%, confirming its suitability for high-performance, chemically aggressive-environment structural concrete. LC³ systems enable 30–50% clinker substitution, yielding an estimated 30–40% embodied CO₂ reduction alongside 6–10% strength gains and 64–90% reductions in chloride migration, representing the most significant decarbonisation opportunity reviewed. Illite-rich clays reduce compressive strength by 6–25%, limiting application to non-structural uses despite moderate durability gains. MM-based clays exhibit highly variable performance, ranging from a 60% strength loss to an 8% gain, with workability penalties of up to a 90% slump reduction, constraining adoption. CW-derived clays achieve 50–69% reductions in chloride diffusion while valorising industrial waste, though strength reductions of 11–20% limit structural applications. Across all clay types, superplasticiser demand increases by 1.5–3.6 times, posing a universal cost and logistics challenge for practitioners in mix design. Full article

Traditional pipe roof support design methods generally assume horizontal ground conditions and treat the pipe roof as a monolithic beam, thereby neglecting the differential stress distribution among individual steel pipes under unsymmetrical loading. To address this gap, this paper presents two main contributions: a low-carbon cement-based grouting material suitable for pipe roof reinforcement, and a new mechanical model that simultaneously accounts for biased pressure conditions and the inter-pipe micro-arch effect. First, the working performance of limestone calcined clay cement (LC³) grout was systematically tested at a water–cement ratio of 1:1, and the optimal mix ratio was determined. Grout–soil reinforcement tests on weathered granite show that, for grout-to-soil volume ratios between 0.2 and 0.8, the compressive strength of the reinforced material exceeds 10 MPa and the elastic modulus exceeds 600 MPa. Second, a mechanical model for the pipe roof was established based on the Pasternak two-parameter foundation theory, incorporating both biased pressure conditions and the inter-pipe micro-arch effect. The model predictions were compared with existing field monitoring data in the literature, showing consistent trends and good agreement in peak deflection values. Parametric analysis reveals that under horizontal ground conditions, the pipe roof response is symmetric, with the vault as the most critical area. As the bias angle increases, the maximum response shifts toward the higher side of the terrain, and the stress difference between pipes on both sides increases significantly. Theoretical analysis of the low-carbon grouting material shows that pipe roof deflection is moderately reduced compared to traditional grouting materials, but at the cost of increasing bending moment and shear force within the steel pipes. The proposed low-carbon grouting material and the validated mechanical model provide theoretical support for the design optimization of pipe roof support in shallow unsymmetrical loading tunnels. Full article

Ca²⁺-rich brines strongly destabilize bentonite-based drilling fluids by weakening hydration and increasing filter-cake permeability. In this work, raw sodium bentonite (Na-Bt) and a series of cation-exchanged bentonites (Li-, Mg-, Ca-, and K-Bt) were comparatively investigated to clarify how cation-dependent hydration characteristics and interlayer structure govern filtration behavior under saline conditions. XRD, zeta potential, TG–DTG, BET, and SEM were employed to correlate basal spacing, surface electrostatic properties, thermal/water-loss behavior, surface area and pore-structure characteristics, and filter-cake microstructure with API fluid loss. Among the examined 2 wt% brines, CaCl₂ produced the most severe deterioration and was therefore selected as the representative screening condition. Under 2 wt% CaCl₂, Li-Bt exhibited the lowest FL_API (141 mL), which was substantially lower than that of Na-Bt (265 mL), indicating the most favorable intrinsic resistance to Ca²⁺-dominated salinity. The cation-exchange analysis further showed that Li-Bt and Mg-Bt had relatively higher calculated exchange degrees than Ca-Bt and K-Bt under the present preparation conditions. Based on the 2 wt% CaCl₂ dataset, a descriptor-based relation between FL_API, hydrated ionic radius (r_h), and basal spacing (d₀₀₁) was established, and an Al-modified bentonite provided an out-of-sample verification with close agreement between predicted and measured filtration loss. Additional tests in 1–3 wt% CaCl₂ showed that although absolute fluid loss increased with brine severity, the relative ranking of the cation-exchanged bentonites remained broadly unchanged. TG–DTG, BET, and SEM results further provided complementary evidence for the structural and microstructural differences among the samples. Overall, the results demonstrate that hydration-related response, interlayer structure, and surface/pore characteristics jointly govern the filtration behavior of cation-exchanged bentonites, providing a useful basis for screening salt-tolerant clay materials for Ca²⁺-rich brines. Full article

Over the last decade, 3D printing of clay has gained attention in architecture. Yet most slicing software is designed for thermoplastics with nozzle sizes between 0.3 and 1.0 mm. Clay printing, using larger nozzles (1–30 mm), requires precise control over path arrangement, material flow, and shrinkage—capabilities not sufficiently addressed by conventional software. This paper introduces Termite, an open-source software plugin for Rhinoceros 3D Grasshopper designed specifically for Liquid Deposition Modeling (LDM) 3D printing. The novelty of this work lies in embedding slicing logic directly into a parametric design environment, enabling explicit and flexible control of printing paths tailored to the rheological behavior of clay. The plugin supports designing, simulating, optimizing, and exporting machine data within a unified workflow. In contrast to conventional slicers, it allows variable printing parameters within a single print job, controlled inrun speeds for smoother path starts, adapted material flow at path crossings, and extrusion flattening at path ends to enhance adhesion and precision. The software was evaluated through multiple architectural-scale case studies and student-based design experiments. Results demonstrate that integrating slicing operations into parametric design workflows enables new fabrication strategies and expands accessibility of clay 3D printing for architectural applications. Full article

This paper studies the sustainable integration of vernacular construction techniques and natural materials in the context of sustainable development, using Danube Delta UNESCO World Heritage site as case study. Through a comprehensive literature review, this research examines the potential of clay-based composites reinforced with plant fibres such as reed, bulrush, and hemp as environmentally responsible building materials. The methodology, based on a narrative literature review, combines bibliometric analysis with a case study approach to evaluate scientific interest in vernacular construction and to identify locally available natural resources. Results reveal increasing academic attention to sustainable vernacular architecture, highlighting clay-based composite’s favourable hygrothermal properties and the remarkable thermal insulation capabilities of vegetable fibres. The case study shows that most Danube Delta’s natural construction materials—particularly the world’s largest continuous reed vegetation—remain underutilized. The research concludes that revitalizing traditional construction methods, by integrating modern technological innovations, presents significant potential for sustainable rural development, preserving cultural heritage, enhancing regional identity, and reducing environmental impact in construction while supporting local economic growth through culturally authentic tourism. Full article

By examining a novel nanomaterial that has been modified for use in sustainable construction, this study primarily responds to the growing need for environmentally acceptable materials. The primary goal was to improve the functional and aesthetic qualities of building materials by synthesizing and characterizing environmentally friendly clay-based nanomaterials doped with cobalt pyrophosphate (Co₂P₂O₄). The authors employed contemporary experimental methods, such as scanning electron microscopy (SEM) for morphological characterisation, Fourier transform infrared spectroscopy (FT-IR) for molecular bonding assessment, and X-ray diffraction (XRD) for crystal structure research. The published findings show the doped nanomaterials’ potential durability as well as their structural integrity. An economic assessment is part of the investigation. The study is noteworthy for emphasizing the potential of cobalt-doped pyrophosphate nanoparticles as eco-friendly colour pigments for construction materials made of clay. Full article

The oxygen evolution reaction (OER), serving as the anodic bottleneck in electrochemical water splitting for hydrogen production, severely limits the overall energy conversion efficiency due to its sluggish kinetics. Developing efficient and stable electrocatalysts based on earth-abundant elements is a critical challenge for advancing clean energy technologies. In recent years, silicate materials have demonstrated significant potential in alkaline OER catalysis owing to their unique stable silicon-oxygen tetrahedral framework and flexibly tunable metal-oxygen-silicon electronic coordination environments. This review systematically summarizes recent progress in silicate-based materials, including natural clay mineral supports such as halloysite, for OER electrocatalysis. It focuses on controllable synthesis strategies for silicate materials and provides an in-depth analysis of the regulation mechanisms for their electronic structure and surface properties through defect engineering, anion vacancy construction, and bimetallic/non-metallic heteroatom doping. Particular emphasis is placed on research pathways that utilize natural silicate clay minerals as both supports and silicon sources to construct high-performance composite catalytic materials via innovative structural design and interface engineering. Systematic studies indicate that precisely modulated silicate-based catalysts exhibit excellent electrochemical activity and long-term stability in the alkaline OER process. This review offers perspectives on the future development of efficient and stable silicate-based catalytic systems for renewable energy conversion. Full article

This study develops a unified multiscale–machine learning framework to interpret and predict thermo-mechanical wear regime transitions in MWCNT- and nanoclay-reinforced bio-based epoxy composites. A physics-informed master wear formulation integrating real contact mechanics, geometry-dependent shear transfer, interfacial adhesion energetics, and fracture-controlled matrix detachment was combined with interpretable machine learning analytics on a unified tribological dataset. In the CNT system, increasing loading from 0.1 to 0.4 wt.% enhanced interfacial adhesion energy density from 0.00813 to 0.01906 J/m², resulting in a monotonic reduction in the wear rate from 0.00918 to 0.00613 mm³/N·m (~33% reduction). In contrast, nanoclay exhibited an optimum behavior, with a minimum wear at 0.25 wt.% (0.000093 mm³/N·m; 7.9% reduction vs. neat clay baseline), followed by deterioration at a higher loading due to dispersion loss. The unified probabilistic regime classification of low-wear conditions (k < 0.007 mm³/N·m) achieved an ROC − AUC = 0.9256 and balanced accuracy = 94.3%, with thermo-mechanical severity identified as the dominant regime-switching driver. Reinforcement identity significantly modulated regime stability, confirming distinct shear transfer (Carbon Nano Tubes(CNT)) and confinement/tribofilm (clay) mechanisms within a common mathematical framework. By enabling the durability-oriented design of bio-based tribological systems and extending component service life through predictive stability mapping, this work contributes to resource-efficient materials engineering and reduced lifecycle waste, supporting Sustainable Development Goals SDG 9 (Industry, Innovation and Infrastructure), SDG 12 (Responsible Consumption and Production), and SDG 13 (Climate Action). Full article

This study presents a comparative evaluation of Environmental Product Declarations (EPDs) within the traditional ceramic industry, emphasizing how differences in data structures, reporting formats, and background databases influence the interpretation of environmental performance. Four product categories—ceramic tiles, sanitary ware, clay bricks, and clay roof tiles—were analyzed using datasets from One Click LCA and the International EPD System. Environmental indicators assessed include fossil-based and total Global Warming Potential (GWP), freshwater consumption, and energy demand, standardized per 1 kg of product. The analysis reveals that discrepancies between platforms arise primarily from the limited level of process-specific information required by current EPD formats, rather than from the platforms themselves. Missing details on raw material composition, firing conditions, and energy sources restrict comparability and hinder the development of robust benchmarks. Furthermore, the study highlights the need for harmonized databases, more transparent PCR requirements, and consistent reporting rules to support meaningful cross-platform comparisons. As the first study to examine EPD data structures for ceramic products across two major reporting systems, it highlights the need to expand product-specific benchmarks and enhance disclosure practices to strengthen the role of EPDs in sustainable market design and climate policy. Full article

The advancement of sustainable construction requires the development of earthen materials compatible with 3D printing (additive manufacturing), along with specified engineering standards. Many existing studies improve workability and early strength using chemical stabilizers such as cement; however, these additives increase embodied carbon and undermine sustainability objectives. Challenges remain in the formulation of an earthen mixture that satisfies both printability and structural requirements for large-scale construction. Previous earth-based mixes have reported excessive shrinkage and inadequate compressive strength. This study presents the systematic optimization of a low-carbon, 3D-printable earthen mixture using locally sourced clay-loam soil from Belén, New Mexico (NM). The soil was modified with graded concrete sand and rice hull fiber to improve printing parameters such as buildability, extrudability, and printability while meeting the NM Earthen Building Code requirements for compressive and flexural strength. Soil characterization tests (particle size distribution, consistency, optimal water content) guided iterative refinement to enhance dimensional stability and mechanical performance. A baseline 2:1 soil-to-sand ratio (max aggregate size No. 4) was established. Incorporating $2\%$ rice hull fiber and reducing max aggregate size to No. 16 (S67F2) early-age shrinkage was reduced from $12.33\%$ to $3.48\%$ ($72\%$ reduction) while maintaining a 28-day compressive strength exceeding 660 psi, more than twice the code minimum. The optimized mixture supported 24 printed layers without deformation, achieved 189 psi flexural strength (three times the code minimum), and produced a stable 2-ft-diameter dome with minimal cracking. Full article

This study aims to investigate the influence of clay mineral content on the rheological properties and long-term deformation stability of clays, and to establish a unified model capable of quantitatively describing the nonlinear rheological behavior of clays with different mineral compositions. Direct shear rheological tests were conducted on specimens prepared with different mixing ratios of bentonite, kaolin, and quartz. Combined with micro-mechanism analysis, the controlling factors of clay rheological behavior were explored. The experimental results show that the creep stress threshold, elastic viscosity, and average plastic viscosity decrease significantly with increasing clay mineral content. The rheological deformation exhibits distinct nonlinear characteristics, and clay mineral content plays a controlling role in the rheological behavior. Based on experimental and mechanistic analysis, a unified rheological model was established, which reflects the material origin of rheology and captures nonlinear rheological characteristics. This model can predict the entire time-history mechanical behavior of clays with different mineral compositions across the three stages of instantaneous deformation, decay rheology, and steady-state rheology under different shear stress levels using a single set of parameters. Validation was performed through direct shear rheological tests under 50 working conditions for five types of clay specimens, demonstrating good consistency between the model calculations and experimental results. The unified rheological model reveals the material origin and physical essence of clay rheology, demonstrates high universality, and advances the understanding of the influence of mineral composition on rheology from the current phenomenological qualitative description to quantitative calculation for the first time, significantly enhancing its engineering application value. This provides a more reliable tool for predicting long-term deformation and assessing the stability of clay foundations. Full article