Search Results (420)

The pursuit of sustainable construction practices has become imperative in the modern era. This paper delves into the research of the properties and application of a specific material called “red clay” from the locality “Crvena Mogila” in Macedonia. A series of laboratory tests were conducted to evaluate the physical, mechanical, and chemical properties of the material. The tested samples show that it is a porous material with low density, high water absorption, and compressive strength in range of 29.85–38.32 MPa. Samples of composite wall blocks were made with partial replacement of natural aggregate with red clay aggregate. Two types of blocks were produced with dimensions of 390 × 190 × 190 mm, with five and six holes. The average compressive strength of the blocks ranges from 3.1 to 4.1 MPa, which depends on net density and the number of holes. Testing showed that these blocks have nearly seven-times-lower thermal conductivity than conventional concrete blocks and nearly twice-lower conductivity than full-fired clay bricks. The general conclusion is that the tested red clay is an economically viable and sustainable material with favourable physical, mechanical, and thermal parameters and can be used as a granular aggregate in the production of composite ceramic blocks. Full article

A major breakthrough in environmentally friendly building materials is the development of sustainable unfired clay bricks including alumina waste produced during liquid nitrogen generation. Though used extensively, conventional fired clay bricks require energy-intensive manufacturing techniques that produce significant amounts of CO₂ and aggravate environmental damage. By removing the need for high-temperature firing and allowing for the valorization of industrial byproducts including alumina waste and lateritic soil, unfired clay bricks offer a reasonable low-carbon alternative. High silica and alumina contents define the alumina waste, which shows pozzolanic reactivity, thus improving the physicomechanical performance of the bricks. With alumina waste substituting 0–8.57% of the cement content, seven different formulations showed improvements in compressive strength, reduced water absorption, and optimal thermal conductivity. Especially, the mechanical performance was much enhanced with alumina waste inclusion up to 30%, without sacrificing thermal insulation capacity or moisture resistance. Further supporting the environmental and financial sustainability of the suggested brick compositions is the economic viability of using industrial waste and regionally derived soils. A comparative analysis of the conventional fired bricks shows that the unfired substitutes have a much lower environmental impact and show better mechanical properties, including greater compressive strength and modulus of rupture. These results support the more general goals of circular economy systems and low-carbon urban development by highlighting the feasibility of including alumina waste and lateritic soil into sustainable building materials. Using such waste-derived inputs in building fits world initiatives to lower resource consumption, lower greenhouse gas emissions, and build strong infrastructure systems. Full article

Exploiting clay for brick production results in soil damage. There are no field evaluations for its recovery with organic amendments comprising biochar. We conducted a small-scale experiment to assess the recovery effects of soil using biochar, both alone and in combination with compost. On a remnant of soil from clay mining, we applied the following to plots of 2.25 m² in a randomized complete block design: (1) biochar + efficient microorganisms (EMs), (2) compost + EMs, (3) compost + biochar + EMs, and (4) a control group without amendments. Composite soil samples from each plot were collected at the beginning of the experiment and at 30, 120, and 210 days. We analyzed some physicochemical properties of the soil and recorded the number and morphotypes of seedlings. We found that biochar + EMs and biochar + compost + EMs had positive effects in the short term, particularly in reducing bulk density. No synergistic effect was observed between biochar and compost, contrary to what was expected, which may be due to the short term of the experiment and prevailing low temperatures. The compost + EM treatment resulted in greater seedling diversity. In conclusion, bulk density can be used as an early indicator of soil improvement when biochar alone or combined with compost is used. Biochar may be a striking solution for promoting sustainable soil management after clay mining in high-elevation conditions. Full article

China is the world’s largest supplier of raw materials and is a major consumer of refractories. The environmental damage that results from the use of refractories has drawn increasing attention. Life cycle emissions of air pollutants and CO₂ associated with the refractory manufacturing industry between 2009 and 2021 were quantified in this study. Particulate matter, SO₂, and NO_x emissions decreased by 7.1% (1515 t), 23.6% (2982 t), and 27.8% (3178 t), respectively, over the aforementioned period despite refractory output volumes being relatively stable. Advancements in manufacturing and purification technologies and internal modifications within the industry played a significant role in these decreases. To sustain output while significantly lowering emissions, the industry shifted toward the production of new minimally polluting refractories and monolithic refractories and away from the production of highly polluting clay bricks. CO₂ emission was reduced by 1.36 million tons as a result of product modifications. A logarithmic mean Divisia index (LMDI) model was used to quantify the driving forces of five factors (pollution production coefficient, control technology level, economic development level, economic structure, and consumption structure) affecting emissions. Three different emission reduction scenarios were simulated, and potential emission reductions of 23.1–77.7% by 2030 were projected. Full article

This study explores the potential of using sustainable materials in brick manufacturing by designing a novel brick mix in the laboratory, incorporating sand, lime kiln dust (LKD) waste, tyre rubber, and ground granulated blast furnace slag (GGBFS) waste. These cementless bricks blended LKD–GGBFS wastes as the binder agent and fine crumb rubber from waste tyres as a partial replacement for sand in measured increments of 0%, 5%, and 10% by volume of sand. Ordinary Portland cement (OPC) and fired clay bricks were sourced from the industry, and their properties were compared to those of the laboratory bricks. Tests performed on the industry and laboratory bricks included compressive strength (CS), freeze-thaw (F-T), and water absorption (WA) tests for comparison purposes. Additionally, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses were performed on the bricks to assess the morphological and mineralogical changes responsible for the observed strengths and durability. The CS and WA values of the engineered bricks were 12, 6, and 4 MPa, and 7, 12, and 15%, respectively, for 0, 5, and 10% crumb rubber replacements. The industry bricks’ average CS and WA values were 13 MPa and 8%, respectively. From the results obtained, the green laboratory bricks passed the minimum strength requirements for load-bearing and non-load-bearing bricks, which can be used to construct small houses. Lastly, the engineered bricks demonstrated strength and durability properties comparable to those of the industry-standard bricks, indicating their potential as a sustainable alternative to help divert waste from landfills, reduce the pressure on natural fine sand extraction, and support eco-conscious brick production for a sustainable environment. Full article

This study focuses on improving the recycled coarse aggregate (RCA) replacement ratio in recycled aggregate concrete products. First, the mix design and compressive performance of recycled aggregate concrete (RAC, RCA replacement percentages of 20%, 35%, and 50%) were evaluated using the monofactor analysis method and response surface methodology under three different conditions: single addition of nano-calcium carbonate (NC, dosages of 0.1%, 0.2%, and 0.3%), single addition of basalt fibre (BF, volume content of 0.1%, 0.2%, and 0.3%), and combined addition of both. The results show that the compressive strength of RAC at 7 and 28 days rises as the BF or NC content increases and then falls as the NC content increases. According to the sensitivity analysis, RAC’s compressive strength is significantly impacted by the replacement ratio of RCA, with NC having a more considerable effect on RAC’s 7-day compressive strength than BF, while BF affects the 28-day compressive strength more than NC does. Based on the desirability function, the ideal BF and NC content in RAC was optimised and confirmed by the compressive strength test. It demonstrates that the best compressive performance is achieved by RAC with 1% NC and 0.3% BF. Finally, concrete pavement brick models were created using the ideal mix proportion provided by the compressive strength test. The model compression test results show that RAC pavement bricks (RCA replacement ratio of 60%) with 1% NC and 0.3% BF had a 28d compressive strength of 5.7% and 15.8% higher than NAC and RAC pavement bricks, respectively. Full article

Currently, the construction industry relies mainly on non-environmentally sustainable materials such as fired clay brick, concrete, and steel, which significantly contribute to global carbon dioxide generation, leading to environmental degradation. In response to mounting environmental concerns, there is a growing emphasis on developing and utilizing low-impact materials that mitigate the ecological footprint of construction activities. This review offers a detailed overview of current formulations and applications of hempcrete and compares the performance of different types of hempcrete as construction materials. Additionally, this paper seeks to evaluate the potential of hempcrete as a sustainable substitute for traditional construction materials with high energy demands and significant CO₂ emissions based on life cycle assessment (LCA). Furthermore, this study summarizes current challenges and prospects for composite innovations in hempcrete, emphasizing the need for standardized product control and broader industrial acceptance, thus providing useful insights for practitioners and researchers in the field. Full article

Coal combustion generates significant volumes of ash, a technogenic by-product that poses a serious threat to regional environmental sustainability (environmental chemical contamination and air pollution). This study aims to assess the feasibility of utilizing this type of ash as a raw material component in the fabrication of refractory bricks and to investigate the fundamental properties of the resulting experimental products. Ash was incorporated into the batch composition at concentrations ranging from 10% to 40% by weight, blended with clay and water, then shaped through pressing and subjected to firing at 1000 °C and 1100 °C in an air atmosphere for 2 h. After complete cooling, the samples were subjected to compressive strength testing. Samples containing 40 wt% coal ash exhibited insufficient compressive strength and were therefore excluded from subsequent investigations. For the remaining samples, apparent density, open porosity and slag resistance were determined. The microstructural characterization was performed, and the phase composition of the samples was analyzed. The results revealed that the phase composition of the experimental samples differs significantly from that of the reference sample (ShA-grade chamotte brick in accordance with GOST 390-96, currently used as lining in metallurgical furnaces across the country), exhibiting a higher mullite content and the absence of muscovite. A small amount of kaolinite was detected in the experimental samples even after a 2-h firing process. This observation may be attributed to the effect of kaolinite crystallinity on the transformation process from kaolinite to metakaolinite. The mechanical strength of the experimental samples meets the relevant standards, while slag resistance demonstrated an improvement of approximately 15%. Open porosity was found to decrease in the experimental samples. In addition, a change in the pore size distribution was observed. Notably, the proportion of pores larger than 10,000 nm was significantly reduced. These findings confirm the feasibility of incorporating coal ash as a viable raw material component in the formulation of refractory materials. Full article

The use of tunnel kiln firing in clay brick production offers a promising approach for disposing of Cl-containing solid waste, with lower chlorine (Cl) and heavy metal volatilization compared to cement kiln processes. However, the effects of Cl salts on brick properties and the volatilization mechanisms remain unclear. This study investigates the behaviors of NaCl, KCl, and CaCl₂ during sintering. Adding 15 wt% Cl salts significantly alters pore structure, increasing water absorption by 80–100% and reducing compressive strength by 70–80%. At 1050 °C, 10.8–16.4% of Cl volatilizes mainly as HCl (g), 24.4–26.2% remains in original salt form, and over half is immobilized within the brick matrix. Thermodynamic and TG-MS analyses reveal Cl salts are stable below 800 °C but release HCl (g) at higher temperatures due to lower reaction energy barriers than Cl₂ (g). Density functional theory (DFT) calculations show that H⁺ for HCl (g) formation primarily originates from water vapor (H₂O), with organic decomposition having minimal effect. The presence of Cl salts promotes feldspar and silicate phase formation, enhancing densification but increasing porosity from HCl release. To reduce HCl emissions, a two-stage temperature control strategy is proposed: organic decomposition and moisture removal below 600 °C, followed by sintering at 800–1000 °C. This work clarifies the volatilization mechanisms of Cl salts and provides guidance for optimizing industrial brick production using Cl-containing waste. Full article

Due to the development of wooden construction as an ecological alternative to brick construction with a high carbon footprint, there is increasing interest in materials such as plywood and LVL (Laminated Veneer Lumber). These engineered wood products have many advantages compared to wood, such as a more uniform distribution of bending, shear, tensile, and compressive strength. However, they require improvements in fire and biological resistance. The flammability of wood and wood composites is a challenge that will allow these materials to stand out as structural or finishing materials. During combustion, toxic gases may be released, which can be harmful to people and the environment. Therefore, it is crucial to clarify whether fire-resistant wood materials are truly resistant to fire and non-toxic in fire conditions. On the other hand, flame retardants should not reduce the mechanical parameters of panels. This work analyses the current requirements (standards) regarding plywood intended for construction and the existing flame retardants for plywood and LVL based on the latest reports in the literature. We then propose an original method for evaluating future chemicals. Additionally, methods for assessing the flame retardancy of plywood and LVL based on the latest reports in the literature are described, and an original method for assessing flame retardancy methods is proposed. Full article

This study introduces an innovative process for stabilizing BOF slag by blowing oxygen into molten slag, addressing challenges associated with conventional methods that require silica injection. Molten BOF slag from a steelmaking workshop at China Steel Corporation is directly modified at the slag modification station, where chemical compositions and crystalline phases are analyzed under varying oxygen injection amounts. In 70 industrial trials (20–25 tons per trial) with the basicity of the BOF slag ranging from 2.2 to 4.5, the reduction in the slag expansion rate increases proportionally with oxygen-blowing amounts. Oxygen blowing facilitates the oxidation of FeO to Fe₂O₃, which reacts with f-CaO to form volumetrically stable C₂AF (brownmillerite, Ca₂Al_xFe_2−xO₅), as confirmed by XRD and SEM-EDX analyses. The treated BOF slag exhibits excellent volumetric stability (expansion < 0.5%), lower pH (10.6–10.8) in comparison to original BOF slag, and compliance with Taiwan’s EPA-leaching regulations. This stabilized slag demonstrates potential for engineering applications, such as pavement bricks, concrete products, and high-value engineered stones. Additionally, the high brownmillerite content highlights its promise for low-carbon cement applications, offering a scalable and cost-effective solution for BOF slag utilization in the steel industry. Full article

Nowadays, the global brick industry utilizes billions of cubic meters of clay soil annually, resulting in the massive consumption of non-renewable resources. This study explores the viability of utilizing red marl from phosphate mining waste rocks for fired brick production. Ecofriendly fired bricks produced from 100% side streams (red marly clays (RM) and marble waste powder (MWP)) were prepared, pressed, dried at 105 °C, and then fired at 1100 °C for 1 h. The effects of marble waste powder addition (up to 30 wt%) on the physical, mechanical, mineralogical, and microstructural properties of the fired bricks were explored. The main results show that fired bricks with high compressive strength of a maximum of 39 MPa could be prepared with a mixture of red marl and 10 wt% of marble waste powder. The thermal conductivity was decreased by marble waste addition (from 0 to 30%) and was reduced from 0.93 W/m.k to 0.53 W/m.k; however, the compressive strength was also decreased to reach a minimum of 17 MPa. The firing shrinkage and density were also reduced with 30% marble waste by 41% and 18%, respectively. Therefore, red marly clays and marble waste could be promising raw materials for eco-fired brick production. Full article

Red mud (RM), a highly alkaline waste from alumina production, poses severe environmental threats due to massive stockpiling (>350 million tons in China) and groundwater contamination. This study evaluates three scalable strategies to repurpose RM: iron recovery via magnetic separation, sintered brick production using RM–fly ash–granulated blast furnace slag (6:1:3 ratio), and non-calcined cementitious binders combining RM and phosphogypsum (PG). Industrial-scale iron extraction achieved 23.85% recovery of iron concentrate (58% Fe₂O₃ grade) and consumed 3.6 million tons/year of RM, generating CNY 31 million annual profit. Sintered bricks exhibited 10–15 MPa compressive strength, meeting ASTM C62-23 standard while reducing material costs by 30%. The RM–PG binder achieved 40 MPa compressive strength at 28 days without cement or calcination, leveraging RM’s alkalinity (21.95% Na₂O) and PG’s sulfate activation. Collectively, these approaches reduced landfill reliance by 50% and CO₂ emissions by 35%–40% compared to conventional practices. The results demonstrate RM’s potential as a secondary resource, offering economically viable and environmentally sustainable pathways for the alumina industry. Full article

There is an increasing demand to replace traditional construction techniques with more sustainable systems that can reduce environmental impacts. Emissions are typically assessed only in carbon dioxide and embodied energy terms, yet these metrics alone cannot fully capture the overall impact generated. This study provides a comparative Life Cycle Assessment (LCA) of three steel warehouse projects with varying cladding systems: steel walls (SW), steel-clay brick walls (SClaW), and steel-concrete block walls (SConW). Life Cycle Assessment (LCA) methodology was used to assess the environmental impact of materials used during the whole life cycle. The study used the software program SimaPro (System for Integrated Environmental Assessment of Products) version 9.6.0.1, with data extracted from the international Ecoinvent database. ReCiPe Midpoint approach were adopted to assess potential impacts. The results indicate that the SW project under end-of-life Scenario 2—waste recycling—exhibited the lowest impacts across most categories, followed by the SConW and SClaW projects. The findings emphasize the environmental benefits of utilizing steel cladding systems over brick or concrete masonry and considering recycling as the end of life of the materials. Additionally, the study provides insights into the significance of material choices in minimizing environmental impact on human health, resource availability, and ecosystems. Full article

The use of recycled burnt clay brick sand (RBS) and recycled concrete sand (RCS) in historical lime-based repair mortars can reduce the environmental impact caused by construction and demolition waste disposal. This study examined the use of fine recycled concrete and recycled brick aggregates for the production of historical repair mortars using hydraulic lime binder and the influence of the resulting mortars on the performance of historical buildings in reduced scale walls (stacks). Natural-river-sand mortar (NSM) was used as control. Results showed that the recycled-burnt-brick-sand mortar (RBSM) performed better in terms of strength compared to the recycled-concrete sand (RCSM) and the NSM mortars. At the age of 7 and 28 days, the flexural strength of the RBSM and the RCSM was 131% and 44%, respectively, and 300% and 68% above that of the control mortar. The 45-day flexural strength of the NSM and RCSM was similar whilst the RBSM mortar’s strength was 177% higher. The compressive strength followed similar trend. On the other hand, the strength and modulus of elasticity of the stacks were found to be largely influenced by the strength of the brick units. Full article