Search Results (51)

High demand for sustainable solutions in the construction industry determines the significant relevance of developing new eco-friendly composites with a reduced carbon impact on the environment. The main aim of this study is to investigate the possibility and efficiency of using technical sulfur (TS) as a modifying additive for geopolymer composites and to select the optimal content of polypropylene fiber (PF). To assess the potential of TS, experimental samples of geopolymer solutions based on metakaolin and fly ash were prepared. The TS content varied from 0% to 9% by weight of binder in 3% increments. In the first stage, the density, compressive and flexural strength, capillary water absorption and microstructure of hardened geopolymer composites were tested. The TS additive in an amount of 3% was the most effective and provided an increase in compressive strength by 12.6%, flexural strength by 12.8% and a decrease in capillary water absorption by 18.2%. At the second stage, the optimal PF content was selected, which was 0.75%. The maximum increases in strength properties were recorded for the composition with 3% TS and 0.75% PF: 8% for compression and 32.6% for bending. Capillary water absorption decreased by 12.9%. The geopolymer composition developed in this work, modified with TP and PF, has sufficient mechanical and physical properties and can be considered for further study in order to determine its competitiveness with cement composites in real construction practice. Full article

This study investigates the synergistic modification of cement–soil using waste brick powder (WBP) and polyvinyl alcohol (PVA) fibers to address the growing demand for sustainable construction materials and recycling of demolition waste. An orthogonal experimental design was employed with 5% WBP (by mass) and PVA fiber content (0–1%), evaluating mechanical properties based on unconfined compressive strength (UCS) and splitting tensile strength (STS) and microstructure via scanning electron microscopy (SEM) across 3–28 days of curing. The results demonstrate that 0.75% PVA optimizes performance, enhancing UCS by 28.3% (6.87 MPa) and STS by 34.6% (0.93 MPa) at 28 days compared to unmodified cement–soil. SEM analysis revealed that PVA fibers bridged microcracks, suppressing propagation, while WBP triggered pozzolanic reactions to densify the matrix. This dual mechanism concurrently improves mechanical durability and valorizes construction waste, offering a pathway to reduce reliance on virgin materials. This study establishes empirically validated mix ratios for eco-efficient cement–soil composites, advancing scalable solutions for low-carbon geotechnical applications. By aligning material innovation with circular economy principles, this work directly supports global de-carbonization targets in the construction sector. Full article

Because the loess widely used in the channel water conservancy projects in the Loess Plateau has a loose structure, low mechanical strength, and is prone to collapse when immersed in water, its comprehensive properties, such as structural strength and water resistance, must be greatly improved. Based on our previous work on the modification of Aga soil in Tibet, China, this study added hydrophobic n-dodecyltrimethoxysilane (WD10) to water glass solution (the main components are potassium silicate (K₂SiO₃) and silicic acid (H₂SiO₃) gel, referred to as PS) to obtain a composite coating PS-WD10, which was sprayed on the surface of loess blocks to achieve a full consolidation effect. We not only systematically investigated the morphology, chemical composition, and consolidation mechanism of the composite coating but also conducted in-depth and detailed research on its application performance such as friction resistance (structural strength), hydrophobicity, resistance to pure water and salt water immersion, and resistance to freeze–thaw cycles. The results showed that the PS-WD10 composite coating had better consolidation performance for loess blocks than the single coating of PS solution and WD10. For the loess block samples coated with the composite coatings, after 50 friction cycles, the weight loss rate was less than 15 wt%, and the water contact angle was above 120°. The main reason is that the good permeability of the PS solution and the excellent hydrophobicity of WD10 produce a good synergistic effect. The loess blocks coated with this composite coating are expected to replace traditional functional materials for water conservancy projects, such as cement and lime, in silt dam water conservancy projects, and also have better environmental protection and sustainability. Full article

The construction industry generates large amounts of waste and high CO₂ emissions, especially from cement production. Sustainable alternatives, such as geopolymers, help reduce these impacts by promoting eco-friendly materials. This study aimed to develop geopolymer mortar using ignimbrite (IG) residues from the Arequipa region, Peru, combined with metakaolin (MK). The raw materials were characterized by X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) to assess the chemical composition, structure, and morphology. Geopolymeric mortars were synthesized with varying MK/IG ratios while maintaining a fixed fine sand proportion. An activating solution of 9 mol/L NaOH was used with different liquid-to-solid ratios. Geopolymers cured at room temperature for 28 days exhibited lower compressive strength than those dried at 50 °C for 48 h or sequentially at 50 °C for 48 h followed by 90 °C for 12 h. The highest IG-content mixture achieved a compressive strength of 18 MPa, while the MK-based geopolymer reached 12 MPa, both under high-temperature curing. An increase in the SiO₂/Al₂O₃ molar ratio was also associated with improved mechanical performance, reinforcing the influence of precursor composition on geopolymerization. These results highlight the potential of regional ignimbrite for the production of geopolymer mortar, promoting sustainable and innovative building materials. Full article

Alkali-activated binders (AAB) are a suitable and sustainable alternative to ordinary Portland cement (OPC), with reductions in natural resource usage and environmental emissions in regions where the necessary industrial residues are available. Despite its potential, the lack of mix design methods still limits its applications. This paper proposes a systematic parametric validation for AAB mix design applied to pastes and concretes, valorizing steel slag as precursors. The composed binders are based on coal fly ash (FA) and Basic Oxygen Furnace (BOF) steel slag. These precursors were activated with sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH) alkaline solutions. A parametric investigation was performed on the mix design parameters, sweeping the (i) alkali content from 6% to 10%, (ii) silica modulus (SiO₂/Na₂O) from 0.75 to 1.75, and (iii) ash-to-slag ratios in the proportions of 75:25 and 50:50, using parametric intervals retrieved from the literature. These variations were analyzed using response surface methodology (RSM) to develop a mechanical model of the compressive strength of the hardened paste. Flowability, yield stress, and setting time were evaluated. Statistical analyses, ANOVA and the Duncan test, validated the model and identified interactions between variables. The concrete formulation design was based on aggregates packing analysis with different paste contents (from 32% up to 38.4%), aiming at self-compacting concrete (SCC) with slump flow class 1 (SF1). The influence of the curing condition was evaluated, varying with ambient and thermal conditions, at 25 °C and 65 °C, respectively, for the initial 24 h. The results showed that lower silica modulus (0.75) achieved the highest compressive strength at 80.1 MPa (28 d) for pastes compressive strength, densifying the composite matrix. The concrete application of the binder achieved SF1 fluidity, with 575 mm spread, 64.1 MPa of compressive strength, and 26.2 GPa of Young’s modulus in thermal cure conditions. These findings demonstrate the potential for developing sustainable high-performance materials based on parametric design of AAB formulations and mix design. Full article

The increasing demand for sustainable and resilient construction solutions calls for the integration of innovative, non-conventional materials in structural retrofitting. This study investigates the use of basalt fiber-based engineered geopolymer composites (BFEGC) as a retrofitting material for fire-damaged reinforced concrete (RC) short columns. A total of 14 columns (150 mm × 150 mm × 650 mm) were cast. Two columns were used as control specimens. The remaining 12 columns were exposed to various fire conditions: 300 °C for 30 min, 600 °C for 20 min, and 900 °C for 15 min, followed by gradual (GC) or rapid cooling (RC). Among the columns, six were left unwrapped (GC-NW, RC-NW), while six others were retrofitted with BFEGC (GC-W, RC-W) and subjected to axial loading until failure. The results showed that BFEGC wrapping improved the mechanical performance of fire-damaged columns, especially at 600 °C. The 600RC-W columns exhibited 1.85 times higher ultimate load, 1.56 times greater displacement ductility, and 2.99 times higher energy ductility compared to unwrapped columns. The strength index and confinement coefficient of the 600RC-W columns increased by 2.31 times and 40.2%, respectively. Microstructural analysis confirmed the formation of salient hydration products under elevated temperatures. BFEGC shows significant reduction in carbon emissions and embodied energy, compared to conventional cement-based binders for fiber-reinforced polymer systems. Full article

The article reviews the literature on the potential utilization of decommissioned wind turbine blade waste (WTBW) in construction materials, including geopolymers, which are rarely discussed. The review indicates that only the mechanical processing of WTBW creates prerequisites for its possible use as fillers in construction materials; however, adjustments to the composition of binding materials are necessary. Wind turbine blades (WTBs) are usually made from strong and durable composite materials, thus posing serious recycling and environmental challenges. Thermal process methods are promising approaches for recovering glass fibers from thermosets of WTBW through pyrolysis or converting WTBW into fibers via plasma processing. Preliminary durability studies of such recovered and recycled glass fibers have demonstrated their potential application in geopolymers or cement-based materials. Implementing these technologies would expand the waste management system, completing recycling and reuse solutions. To successfully adopt more environmentally friendly solutions, further development of geopolymer production processes and sustainable fiber recovery is recommended. Full article

The resource utilization of marine-dredged sediment is considered a sustainable approach to its disposal. This paper investigates the preparation of non-sintered ceramsites from marine-dredged sediments and CSA cement via cold-bonded pelletization. The study examines the effects of various preparation conditions on the engineering properties, phase compositions and microstructures of non-sintered ceramsites. The results indicate that preparation conditions significantly influence the particle size distribution of non-sintered ceramsites. The early-strength development of non-sintered ceramsites prepared from CSA cement is remarkable, with the PCS achieving approximately 60% and 80% of the 28-day strength within 3 days and 7 days, respectively—a marked contrast to OPC. Response surface methodology analysis reveals significant interaction effects between the disc rotation angle, rotational speed, and duration of rotation on the PCS of non-sintered ceramsites. The open-ended porosity of non-sintered ceramsites exhibits greater sensitivity to changes in preparation parameters compared to closed-ended porosity and total porosity. The preparation conditions have negligible impact on the hydration process of CSA cement in non-sintered ceramsites. For both ellipsoidal and plate-like marine-dredged soil particles, ettringite and the AH₃ phase provide effective pore-filling and binding effects in the microstructures of non-sintered ceramsites. These findings imply that low-carbon utilization of marine-dredged sediments through the preparation of non-sintered ceramsites offers a nature-based solution for sustainable management in coastal systems. Full article

Immediate action is required to achieve carbon neutrality within the cement industry. The integration of biochar into cement as a component of reinforced concrete has potential to mitigate carbon emissions in the construction sector by enabling carbon sequestration. In pursuit of eco-friendly practices and improved physical properties of cement composites, this study investigated the properties of wood-based, micron-sized biochar as a non-carbonate raw material, including its chemical composition, morphology, and wettability. The characterization of lignocellulosic micro-biochar and its mechanical impact on cement composites was a focus of this study. Cement was partially replaced with varying weight percentages of micro-biochar (1, 3, and 5 wt%), and the effects were evaluated through compressive strength tests after 7 and 28 d. The results demonstrated that the micro-biochar could sustain strength even when substituted for cement. Notably, after 28 d, the compressive strength of the sample with only cement was 29.6 MPa, while the sample with 3 wt% biochar substitution showed 30.9 MPa, indicating a 4.4% increase. This research contributes to sustainable construction practices by offering a green solution for reducing carbon emissions in the industry. Full article

Cement-based foam composites have gained attention as innovative and high-performing adsorbents for wastewater treatment due to their lightweight, porous, and structurally robust properties. This study investigates the adsorption of Eriochrome Black T dye onto biochar-modified cement foam, providing a cost-effective solution for industrial wastewater management. The integration of biochar into cement foam enhances its surface area and adsorption capabilities while maintaining structural stability and tunable porosity. The composites were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy-dispersive X-ray spectroscopy to verify quality and functionality. The adsorption process adhered to the Freundlich isotherm model (R² = 0.967), indicating multilayer adsorption, with a maximum capacity of 13.33 mg/g under optimal conditions. Kinetic studies showed a pseudo-first-order fit (R² = 0.981), while thermodynamic analysis revealed a spontaneous and endothermic process, with ΔH° = 28.84 KJ/mol and ΔG° values ranging from −0.457 to −2.36 KJ/mol. These results demonstrate the composite’s exceptional efficiency and scalability, making it a sustainable and practical option for removing persistent dyes such as Eriochrome Black T. This work contributes significantly to the advancement of environmentally friendly wastewater treatment technologies. Full article

In this study, numerical simulations using the Abaqus finite element model were performed to evaluate the effects of incorporating waste tyres of varying sizes into the base layer as part of a coupled tyre–pavement structure. The tyre-reinforced structure demonstrated superior deformation resilience, attributed to the hyperelastic properties of tyre rubber, underscoring its potential for applications where deformation recovery is essential. For achieving a uniform settlement, the entire tyre stacking scheme is recommended, whereas the one-third tyre configuration is ideal for minimising displacement. The one-half tyre configuration provides a balanced approach, optimising resource utilisation for structures with moderate performance requirements. The inclusion of tyres increases the equivalent stress within the cement-stabilised gravel layer beneath the tyre, and this effect is less pronounced with smaller tyre sizes. Notably, the projected portion of the tyre tread enhances the bearing capacity of the base structure, improving the load distribution and overall structural performance. The middle and bottom surface layers were identified as the most critical for controlling deformation and stress distribution, while a moderate modulus is advised for the surface course to achieve a balance between deformation control and stress uniformity. The integration of high-modulus layers with tyre reinforcement offers an optimised solution for both deformation management and stress distribution. This study highlights the potential of tyre-reinforced pavements as an innovative and sustainable construction practice, particularly suited for light to moderate traffic conditions. Further research is recommended to explore the long-term environmental and economic benefits, as well as the impacts of tyre composition and ageing on performance. Full article

Underground cold storage gives rise to special challenges that require innovative solutions to ensure maximum energy efficiency. Conventional energy systems tend to be based on high energy use, so sustainable solutions are crucial. This study explores the novel idea of biomimetics and how it might be used in the planning and building of underground cold storage facilities as well as other infrastructure projects. Biomimetic strategies, inspired by termite mounds, gentoo penguin feathers, and beehive structures, are applied to minimize reliance on energy-intensive cooling systems. These natural models offer efficient thermal regulation, airflow optimization, and passive cooling mechanisms such as geothermal energy harvesting. The integration of naturally driven convection and ventilation ensures stable internal temperatures under varying conditions. Biomimicry was employed in Revit Architecture, coupled with structural optimization, to eliminate urban space’s limitations and further increase energy efficiency. The analytical work for this paper utilized a set of formulas that represent heat flow, thermal resistance, R-value, thermal transmittance, U-value, solar absorption, and G-value. The results pointed to very good insulation, with exterior walls having an R-value of 10.2 m²K/W and U-value of 0.98 W/m²K. Among the chosen 3-layer ETFE cushion with a U-value of 1.96 W/m²K, with a G-value of 0.50, showed good heat regulation and daylight management. Furthermore, bagasse-cement composites with a very low thermal conductivity of 0.10–0.30 W/m·K provided good insulation. This research proposes a scalable and sustainable approach in the design of underground cold storage by merging modelling based on Revit with thermal simulations. Biomimicry has been demonstrated to have the potential for changing subterranean infrastructure, conserving energy consumption, and creating eco-friendly construction practices. Full article

There is a growing demand for sustainable solutions in civil engineering concerning the carbon footprint of cementitious composites. Alkali-Activated Binders (AAB) are materials with great potential to replace ordinary Portland cement (OPC), with similar strength levels and lower environmental impact. Despite their improved environmental performance, their durability remains a gap in the literature, influenced by aspects of mechanical behavior, physical properties, and microstructure. This paper aims to assess the impact of steel slag aggregates and curing temperature of a proposed AAB based concrete formulation by characterizing fresh state, mechanical behavior, and microstructure. The proposed AAB is composed of fly ash (FA) and basic oxygen furnace (BOF) steel slag (SS) as precursors, sodium silicate and sodium hydroxide solution as activators, in total replacement of OPC, using baosteel slag short flow (BSSF) SS as aggregate in comparison with natural aggregate. The concrete formulation was designed to achieve a high-performance concrete (HPC) and a self-compacting concrete (SCC) behavior. Mechanical characterization encompassed hardened (compressive strength and Young’s modulus), fresh state (J-ring, slump flow, and T50), and durability tests (scanning electronic microscopy, water penetration under pressure, and chloride ion penetration). The compressive strength (64.1 ± 3.6 MPa) achieves the requirements of HPC, while the fresh state results fulfill the SCC requirements as well, with a spread diameter from 550 mm to 650 mm (SF-1 class). However, the flow time ranges from 3.5 s to 13.8 s. There was evidence of high chloride penetrability, affected by the lower electrical resistance inherent to the material. Otherwise, there was a low water penetration under pressure (3.5 cm), which indicates a well-consolidated microstructure with low connected porosity. Therefore, the durability assessment demonstrated a divergence in the results. These results indicate that the current durability tests of cementitious materials are not feasible for AAB, requiring adapted procedures for AAB composite characterization. Full article

Faced with the growing demand for energy-efficient construction and the need to address environmental challenges, the building sector must innovate to reduce energy consumption and promote sustainability. This study investigates a dual solution to these challenges by enhancing the thermo-mechanical performance of building materials through the integration of textile fiber waste, using a combination of experimental and computational methodologies. This investigation focused on incorporating textile fiber wastes in cementitious composites for construction applications. A series of mechanical and thermal tests were carried out on the cement mortars with different proportions of incorporated textile fibers after 7 and 28 days of water curing. The results showed that the incorporation of fibers can significantly improve the thermal insulation of buildings by reducing the thermal conductivity of cement mortar by up to 52%. To complement experimental findings, computational models were developed using COMSOL Multiphysics 6.2 software to predict the thermal diffusivity and volumetric heat capacity of textile-reinforced mortars. These models revealed that mortars incorporating 40% textile fibers as a sand replacement achieved significant reductions in thermal conductivity, thermal diffusivity, and volumetric heat capacity by approximately 40%, 21%, and 23%, respectively, compared with ordinary cement mortar. Furthermore, this study numerically examined the potential of combining textile-reinforced mortar with phase-change material (PCM) in building applications. The aim of the research was to overcome the challenges of cooling buildings in scorching summer conditions. The optimization of roof and wall composition was based on an assessment of air temperature variation within a space. Full article

The requirement for high-quality drinking water and the treatment of wastewater prior to discharge into the environment results in the generation of sludge. As with any high-volume materials, beneficial reuse applications are being sought to promote sustainable environmental solutions. This research examined the possibilities of producing sustainable lightweight concrete using modified solidified wastewater sludge as a partial replacement of cement. Wastewater sludge was modified by the addition of aluminum oxide and magnesium silicate hydrate. The properties of the modified wastewater sludge were examined, as well as the influence of the partial cement replacement with the sludge in lightweight concrete. Besides testing the physical and mechanical properties of four mortar mixtures, an additional analysis of the willingness of final users to accept novel material containing wastewater sludge was addressed. The results obtained for the mortar samples indicate that 20% cement replacement is the upper limit for the modified sludge’s application. The lightweight concrete prepared with the modified sludge (in the amount of 20%) was tested in a hardened state. The water permeability was reduced by 33.3% with the addition of the modified sludge. Both tested concrete mixtures showed good frost resistance. The maximal measured reduction in the compressive strengths was 7.6%. Citizens’ perceptions and responses regarding the beneficial reuse of materials emphasize the importance of comprehensive education for their future acceptance. Full article