The construction industry requires sustainable building materials to reduce its environmental impact. While using these materials in newly constructed structures primarily focuses on environmental benefits, their application in the protection of architectural heritage presents an additional requirement. These materials must be physically and chemically compatible with historical substrates to ensure the longevity of the structure. Therefore, developing eco-friendly and compatible restoration materials is a significant concern. This study aims to produce artificial aggregates to develop lightweight concrete for structural interventions and reduce natural resource consumption (i.e., minimizing the destructive extraction of natural river sand and crushed stone aggregates). Magnesium-based binders were used to mimic the carbonation process of historical lime mortars. The binders were mixed with water, shaped into coarse pellets, and cured in a CO2 incubator for 3 and 14 days before being used in concrete production. The results show that using artificial aggregates decreased the concrete density by approximately 16.5%. Since reducing the dead load improves the seismic safety of historical masonry structures, this reduction is critical. Although the compressive strength decreased compared to natural aggregate concrete, the 14-day cured series achieved a strength of 34.7 MPa. This demonstrates that the material can be used in restoration interventions where stiffness compatibility is essential (e.g., vault infills, ring beams, or floor screeds). At the same time, since magnesium-based artificial lightweight pellets have CO2 sequestration capacity, they can be used as a carbon-negative solution for both historical structures and broader civil infrastructure.

Effects of co-present mineral colloids on the transport of microplastics in porous media: The key role of hydrochemical and hydrodynamic conditions.

The growing consumption of natural river sand in concrete manufacturing has led to serious environmental degradation and material scarcity, emphasizing the need for sustainable substitute materials. Copper slag, a by-product generated during the copper smelting process, has emerged as a potential alternative to fine aggregate in high-strength concrete. This investigation examines the behavior of M60 grade concrete in which copper slag replaces natural sand at proportions of 0%, 20%, 40%, 60%, 80%, and 100%. The fresh concrete properties were assessed using slump cone tests, whereas the hardened properties were evaluated through compressive strength tests conducted at 7, 14, and 28 days, along with split tensile and flexural strength tests performed at 28 days. The experimental results revealed an increase in workability with rising copper slag content, attributed to its smooth surface characteristics and minimal water absorption capacity. The highest compressive strength was recorded at a 40% replacement level, showing noticeable improvement over the conventional mix. However, replacement levels exceeding 60% resulted in a reduction in strength due to increased free water content and weaker interfacial bonding between the paste and aggregates. Similar performance patterns were observed for split tensile and flexural strengths, with optimal results obtained within the 40–60% replacement range. The study concludes that copper slag can effectively substitute up to 60% of natural sand in M60 grade concrete without adversely affecting structural performance, thereby supporting sustainable construction and efficient utilization of industrial waste.

This study evaluates the energy performance of three solar drying systems operating under the climatic conditions of Chachapoyas, Peru: a natural convection dryer (D0), a dryer with non-continuous forced-air extraction (D1), and a forced-air dryer incorporating thermal energy storage using river sand in the collector (D2). The systems were operated simultaneously under identical environmental conditions. The experimental evaluation was conducted over a 30-day period between July and September 2025, with monitoring from 06:35 to 18:17 h at 5-minute intervals. Solar radiation, ambient conditions, and temperature profiles were recorded using an Arduino-based data acquisition system. Available solar energy ranged from 1589.56 to 6047.25 Wh·m⁻². The system with thermal storage (D2) achieved the highest mean thermal efficiency (46.04 ± 11.66%), followed by D0 (45.82 ± 10.45%), while D1 showed the lowest efficiency (39.67 ± 10.08%). Thermal storage improved energy stability and reduced sensitivity to solar variability conditions overall.

This study employed iron tailings sand (ITS) at different replacement ratios (0%, 25%, 50%) to substitute river sand in the preparation of iron tailings sand cast-in-situ concrete (ITS-CISC). Through macroscopic performance tests and microstructural characterization, the effects of ITS content on the performance of concrete in distilled water, sulfate, and sulfate-chloride corrosion environments are systematically investigated. Results show that after 180 days of sulfate and sulfate-chloride corrosion, incorporating 25% ITS increases the compressive strength of concrete by 8.69% and 6.22%, respectively. Sulfate-chloride corrosion aggravates the deterioration of concrete. At 180 days, the compressive strength of specimens with 25% ITS content in the sulfate-chloride environment is 7.53% and 26.67% lower than that in the sulfate and distilled water environments, respectively. In sulfate and sulfate-chloride environments, ITS enhances mechanical interlocking between particles and promotes the formation of hydration products, thereby increasing the compactness of the interfacial transition zone.

The rapid industrial development has led to a global shortage of fresh water and river sand. A promising solution involves using seawater and sea-sand as alternative raw materials to produce seawater sea-sand concrete (SSC), and using fiber-reinforced polymer (FRP) owing excellent corrosion resistance as confinement material to produce FRP-confined SSC with reasonable performance. This study aims to investigate the axial compressive behavior of FRP-confined SSC experimentally and evaluate the existing predictive models. A total of 48 short columns and 48 standard cubes were tested. The studied parameters in the experiments covered the type of concrete as well as the type and thickness of FRP. The test results indicated that concretes incorporating seawater exhibited higher early-age strength but comparable 28-day strength to normal concrete; under the same FRP confinement condition, different types of concrete showed similar behavior, including dilation performance, axial stress-strain response and ultimate condition. It can be deduced that seawater and sea-sand substitutions have negligible influence on the performance of FRP-confined concrete. Moreover, a database including existing FRP-confined SSC specimens was established and used to evaluate the applicability of existing analysis-oriented models for FRP-confined SSC. The results showed that the model developed by Jiang and Teng demonstrates the highest predictive accuracy.

Replacing river sand in concrete: a review of emerging sustainable fine aggregate materials

Future water availability and crop yields in Kenya’s Sand River Basin enhanced by elevated CO2 under climate change

Sand and gravel mining is a significant human activity essential for meeting the world's infrastructure development and construction needs. This review compiles recent studies on the environmental and socio-economic effects of river sand and gravel mining. We followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines for this study. The guideline emphasises thorough reporting of the review's purpose and methodology, including research selection, data collection, data inclusion, exclusion and synthesis. This review highlights the problems and effects of sand and gravel mining using a Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis, specifically on the Indian context through the integration of detailed, region-specific case studies. Studies from all around the world that present an overview of the sand and gravel market, highlighting the main trends, production, export and import are included in this review. Riverbed morphological changes, habitat degradation, and alterations in aquatic biodiversity are among the physical and ecological effects examined. Hydrological effects include changes in river flow patterns, sedimentation, and water quality deterioration. Socio-economically, this practice can simultaneously offer and impede local economic advantages. Furthermore, the informal practices associated with sand and gravel mining can result in disputes, uncontrolled exploitation, and adverse socio-economic effects. Finally, a series of suggestions for developing a global agenda on sustainable sand and gravel extraction was provided for stakeholders' informed decision-making in mitigating the challenges posed by river sand and gravel mining while fostering a harmonious coexistence between human development and nature.

This study investigates the sulfate durability performance of concrete incorporating lead-zinc tailings sand (LZTS) as partial replacement for fine aggregates. Greater emphasis is placed on long-term resistance to sulfate attack rather than on strength enhancement, ensuring full consistency with the manuscript title. Sulfate exposure conducted in a 5% Na2SO4 solution for periods of up to 180days, during which mass change, linear expansion, surface degradation, and residual mechanical strength were systematically evaluated. The results demonstrate that optimized levels of LZTS replacement, in combination with low-dosage hybrid nanomaterials, significantly enhance the sulfate resistance while maintaining satisfactory mechanical performance. From a sustainability perspective, replacement of up to 50% of natural river sand is achievable, contributing to reduced depletion of natural resources. Microstructural observations obtained from SEM, supported by XRD and FTIR analyses, provide indirect yet consistent evidence of matrix densification and suppression of sulfate reaction products. FTIR spectra confirmed these observations by intensifying Si-O-Si and Al-O-Si bands and weakening Sulfate-associated vibrations with Heavy metal immobilization efficiency exceeding 90%. The findings reveal the potential of LZTS-based concrete as a durable and environmentally responsible construction material for sulfate-rich environments.

The leather industry generates substantial solid waste, with shaving and buffing dust comprising approximately 20% of total tannery residues. Improper disposal of this protein-rich chromium-containing waste leads to significant environmental pollution. The feasibility of incorporating leather shaving and buffing dust, combined with rice husk ash (RHA) and river sand, into non-fired bricks, aiming to convert waste into sustainable construction materials, was investigated. Bricks were fabricated by partially replacing clay (0-20 wt%) with a mixture of leather dust and RHA in varying proportions, with and without cement, and were cured for 7, 14, and 28days. Comprehensive characterization, including FT-IR, XRD, WD-XRF, TGA/DTG, XPS, and leaching tests, was conducted to evaluate physicochemical, mechanical, and environmental performance. The presence of chromium predominantly in the stable trivalent state (Cr3+) and its effective encapsulation within the brick matrix was confirmed by XPS analysis. The optimal composition, containing 10% leather dust and RHA with Gazipur Clay and 15% cement, achieved a compressive strength of 20.03MPa at 28days, meeting ASTM and BDS standards. Chromium leaching remained well below permissible limits, indicating effective immobilization. A time-dependent increase in chromium leaching was observed (0.1562ppm at 7days to 0.40195ppm at 28days), reflecting a diffusion-controlled release, yet remained well below permissible limits, demonstrating effective immobilization. Circular economic principles are supported by this approach by transforming hazardous waste into value-added construction materials. The findings suggest significant potential for industrial-scale application of leather waste-based bricks, contributing to sustainable, cost-effective, and eco-friendly building material production.

Abstract To alleviate the shortage of natural sand resources and enhance the resource utilization of waste glass, this study investigates the effect of partially replacing natural river sand with ground waste glass sand on the bond performance of the steel–concrete interface. Pull‐out specimens were designed with varying glass sand replacement ratios (0%, 10%, 30%, and 50%) and bond lengths (3d, 5d). Distributed optical fiber sensors were employed to monitor the strain distribution and its evolution at the interface. The mechanism through which glass sand influences bond performance was explored by comprehensively analyzing the failure modes, bond strength, slip, and strain characteristics. The results showed that: (1) specimens with a longer bond length (5d) and higher glass sand content were more prone to splitting failure, primarily because the circumferential tensile stress exceeded the concrete's tensile strength; (2) for a 3d bond length, the specimen with 30% glass sand content achieved the highest bond strength (calculated as the average shear stress over the nominal bonded area) of 38.18 MPa, whereas for a 5d bond length, the 10% replacement ratio was most effective (24.47 MPa); (3) except for the 10% replacement group, specimens with a 3d bond length generally exhibited higher bond strength than those with a 5d bond length, indicating that bond performance is not linearly positively correlated with bond length; (4) the bonding performance significantly decreased at high glass sand content (50%) due to the weakening of the interfacial transition zone, potential alkali‐silica reaction, and grading imbalance. This study demonstrates that an appropriate amount of glass sand (10%–30%) can effectively improve the interfacial properties under specific bonding conditions, providing theoretical support for the high‐value utilization of waste glass resources and the design of green concrete.

Agarwood (Aquilaria malaccensis Lamk) is a tree species with high economic value due to its resin, widely used in the perfume, pharmaceutical, and religious industries. However, overexploitation and habitat degradation have led to a significant decline in its natural population. This study was conducted using a controlled experiment to evaluate the effects of various planting media on the growth of A. malaccensis seedlings. The experiment employed a Completely Randomized Design (CRD) with seven media combinations and three replications, using 84 seedlings in total. The results showed that the combination of topsoil, peat, and river sand yielded the highest survival rate (100%) and significantly better growth performance compared to other treatments, with average plant height of 28.7 cm, stem diameter of 0.29 cm, and 27.4 leaves. This medium supports optimal growth by combining organic nutrients (peat), structural stability (topsoil), and effective drainage (river sand). Other viable alternatives include peat + river sand or topsoil + peat, depending on local availability. The findings offer a practical, evidence-based model for sustainable agarwood cultivation and a replicable approach to ex-situ conservation. Keywords: Agarwood (Aquilaria malaccensis Lamk), ethnobotanical studies, planting media, conservation.

This study investigated the degradation behavior of cast-in-situ mortar incorporating iron ore tailings (IOTs) as a partial replacement for river sand under combined attack involving sulfate, magnesium, and chloride ions (distilled water, internal attack, external attack, and internal–external attack). Throughout the exposure period, changes in appearance, size, mass, and mechanical properties were monitored; meanwhile, microstructural, mineralogical, and pore structure evolution were characterized using scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD), thermogravimetry/differential thermogravimetry (TG/DTG), and nuclear magnetic resonance (NMR). The results indicate that the incorporation of 25% IOTs demonstrates optimal mechanical properties and attack resistance. Internal attack more significantly impairs the mechanical improvement from 25% IOTs. The compressive strength increases by 17.65% under external attack alone, in contrast to less than 10% for internal or combined attack. At 50% IOTs content, the improvement effect is significantly reduced compared to that at the 25% content.

With the depletion of natural sand and gravel resources and increasing emphasis on environmental protection, natural aggregates suitable for concrete production are becoming increasingly scarce. Steel slag, a by-product of steelmaking, is produced in substantial quantities yet remains underutilized due to its low recycling rate. Owing to the high strength and excellent compatibility of steel slag particles with cementitious materials, they demonstrate significant potential as a replacement for natural river sand in fine aggregate applications. However, the volumetric instability of steel slag has long been a major impediment to its widespread adoption in cement-based composites. This study examines the stability performance of cement mortar containing steel slag aggregate, with the objective of clarifying the mechanisms responsible for dimensional instability resulting from steel slag incorporation. When the replacement level exceeds 40%, the dimensional stability of the mortar deteriorates markedly. The initial contents of free CaO (f-CaO) and free MgO (f-MgO) in the steel slag were determined to be 1.58% and 1.14%, respectively. Following 50 h of hydrothermal treatment, 69.6% of f-CaO and 44.3% of f-MgO had hydrated, causing internal volumetric expansion and subsequent particle fracturing. Under elevated temperature conditions, over-burned lime demonstrated 220% volumetric expansion and completed its reaction within 40 min, consequently impairing early-age stability. In contrast, periclase (dead-burned MgO) exhibited 34% expansion and attained a reaction degree of merely 13.3%, suggesting a more substantial impact on long-term stability. For each mixture, linear expansion measurements were performed on n = 5 independent specimens, and results are reported as mean ± standard deviation.

Fillers are particles added to the material or mixed in order to reduce the excessive utilisation of binderand at the same time improve some properties of the mixture, from past study several materials have been usedas fillers in the replacement of either cement or fine. This paper presents a review of past studies on the filler effectof various nonreactive materials as fillers. Materials like ground river sand, limestone dust, ground quartz, carbonblack, quarry dust and marble dust are reviewed. Based on analysis, it has been proven that filler plays a significantrole in concrete, not only contributing to strength improvement and other properties in concrete, but also whenused as a replacement for cement or fine aggregate, whereby minimizing the excessive consumption ofconventional materials. However, it can be concluded from past studies that in replacement level of the variousmaterials as filler in concrete, the replacement should be in the range of 2 to 15% for a sustainable concretestructure. Furthermore, as the particle size of the filler affects the performance of the concrete, it is thus concludedthat a finer particle size range of the filler should be in the range of 0.025 to 6μm for better results and filling abilityor particle packing.

Alkali-activated materials (AAMs) or geopolymers have been considered for many years as a sustainable substitution for the traditional ordinary Portland cement (OPC) binder. However, their production needs energy consumption and creates carbon emissions. Since construction and demolition waste (CDW) can become precursors for manufacturing alkali-activated materials, their use as substitutes for traditional AAM (such as metakaolin, blast furnace slag, and fly ash) can solve both the problem of their disposal and the problem of sustainability. Furthermore, CDW can also be used as aggregate replacement, avoiding the exploitation of natural river sand and gravel. A new circular economy could be created based on CDW recycling, creating a new eco-friendly building practice. Unfortunately, this process is quite difficult owing to several variables that should be taken into consideration, such as the possibility of separating and sorting the CDW, the great variability of CDW composition, the cost of the mechanical and thermal treatment, the different parameters that compose an alkali-activated mix-design, and public opinion still being skeptical about the use of recycled materials in the construction sector. This review tries to describe all these aspects, summarizing the results of the most interesting studies performed on this subject. Today, thanks to a comprehensive protocol, the use of building information modeling (BIM) software and machine learning models, a large-scale reuse of CDW in the building industry appears more feasible.

Phalsa (Grewia asiatica L.) is the chief underutilized fruit crop of India which can be propagated by rooting of hardwood cuttings but it depends upon the environmental conditions and the rooting media used for it. Hence, a research study was conducted at the Horticultural Experimental area, Khalsa College, Amritsar during 2023-24 to determine the effect of rooting media on the rooting potential of phalsa stem cuttings at different planting time. The treatments included three planting times (Last week of June, July and August) and four types of rooting media (Canadian peat moss, sterilized river sand and soil (3mix) (1:1:1) (v/v/v) ; Fermented pine bark and sterilized river sand (Bark mix) (1:1) (v/v) ; Soil and sterilized river sand (Peat mix) (2:1) (v/v) and soil) laid out in factorial randomized design replicated thrice. The results of the study stated that the June planting showed maximum results in all the observed parameters in terms of sprouting, rooting in terms of root number, length and root weight and vegetative traits including shoot formation, diameter and shoot weight respectively under the soil alone and mixed with the other rooting media.

Large-scale artificial surcharge loading often triggers landslides in colluvial deposits, yet the mechanical response and failure mechanisms of such slopes under loading remain insufficiently understood. Using a typical colluvial slope in Tibet as a case study, this research integrates physical model tests and FLAC3D simulations to investigate loading-induced deformation and failure processes. Analogous materials composed of river sand, barite powder, calcium carbonate powder, and water were prepared, and multiple regression analysis was used to establish empirical relationships between mix ratios and the resulting cohesion and internal friction angle, yielding high similarity (). Under loading, the slope exhibits maximum vertical and horizontal displacements of 40 mm and 50 mm, respectively, with shear stress concentrated along the loading boundary and vertical stress penetrating deeper than horizontal stress. The slope undergoes progressive failure: loading → initial equilibrium failure → rear-edge tensile cracking → upper soil mass sliding → front-edge extrusion and bulging → sliding surface propagation → overall failure. Furthermore, the colluvial slope exhibits pronounced failure sensitivity under loading, particularly in the progressive development of rear-edge tensile cracking, toe bulging, and deep shear bands, which should be regarded as key indicators for monitoring. These findings clarify the typical loading-induced failure mechanisms of accumulation-body slopes and provide a scientific basis for early landslide identification and hazard mitigation.

Large-scale artificial surcharge loading often triggers landslides in colluvial deposits, yet the mechanical response and failure mechanisms of such slopes under loading remain insufficiently understood. Using a typical colluvial slope in Tibet as a case study, this research integrates physical model tests and FLAC3D simulations to investigate loading-induced deformation and failure processes. Analogous materials composed of river sand, barite powder, calcium carbonate powder, and water were prepared, and multiple regression analysis was used to establish empirical relationships between mix ratios and the resulting cohesion and internal friction angle, yielding high similarity ([Formula: see text]). Under loading, the slope exhibits maximum vertical and horizontal displacements of 40 mm and 50 mm, respectively, with shear stress concentrated along the loading boundary and vertical stress penetrating deeper than horizontal stress. The slope undergoes progressive failure: loading → initial equilibrium failure → rear-edge tensile cracking → upper soil mass sliding → front-edge extrusion and bulging → sliding surface propagation → overall failure. Furthermore, the colluvial slope exhibits pronounced failure sensitivity under loading, particularly in the progressive development of rear-edge tensile cracking, toe bulging, and deep shear bands, which should be regarded as key indicators for monitoring. These findings clarify the typical loading-induced failure mechanisms of accumulation-body slopes and provide a scientific basis for early landslide identification and hazard mitigation.