Search Results (30)

The construction industry is responsible for 39% of global CO₂ emissions related to energy use, with cement responsible for 5–8% of it. Limestone calcined clay cement (LC³), a ternary blended binder system, offers a low-carbon alternative by partially substituting clinker with calcined clay and limestone. This study investigated the use of waste clay brick powder (WBP), a waste material, as a source of calcined clay in LC³ formulations, addressing both environmental concerns and SCM scarcity. Two LC³ mixtures containing 15% limestone, 5% gypsum, and either 15% or 30% WBP, corresponding to clinker contents of 65% (LC³-65) or 50% (LC³-50), were evaluated against general purpose (GP) cement mortar. Tests included setting time, flowability, soundness, compressive and flexural strengths, drying shrinkage, isothermal calorimetry, and scanning electron microscopy (SEM). Isothermal calorimetry showed peak heat flow reductions of 26% and 49% for LC³-65 and LC³-50, respectively, indicating a slower reactivity of LC³. The initial and final setting times of the LC³ mixtures were 10–30 min and 30–60 min longer, respectively, due to the slower hydration kinetics caused by the reduced clinker content. Flowability increased in LC³-50, which is attributed to the lower clinker content and higher water availability. At 7 days, LC³-65 retained 98% of the control’s compressive strength, while LC³-50 showed a 47% reduction. At 28 days, the compressive strengths of mixtures LC³-65 and LC³-50 were 7% and 46% lower than the control, with flexural strength reductions being 8% and 40%, respectively. The porosity calculated from the SEM images was found to be 7%, 11%, and 15% in the control, LC³-65, and LC³-50, respectively. Thus, the reduction in strength is attributed to the slower reaction rate and increased porosity associated with the reduced clinker content in LC³ mixtures. However, the results indicate that the performance of LC³-65 was close to that of the control mix, supporting the viability of WBP as a low-carbon partial replacement of clinker in LC³. Full article

To promote the large-scale utilization of construction and industrial solid waste in engineering, this study focuses on developing accurate prediction and optimization methods for the unconfined compressive strength (UCS) of composite recycled mortar. Innovatively incorporating three types of recycled powder (RP)—recycled clay brick powder (RCBS), recycled concrete powder (RCBP), and recycled gypsum powder (RCGP)—we systematically investigated the effects of RP type, replacement rate, and curing period on mortar UCS. The core objective and novelty lie in establishing and comparing three artificial intelligence models for high-precision UCS prediction. Furthermore, leveraging GA-BP’s functional extremum optimization theory, we determined the optimal UCS alongside its corresponding mix proportion and curing scheme, with experimental validation of the solution reliability. Key findings include the following: (1) Increasing total RP content significantly reduces mortar UCS; the maximum UCS is achieved with a 1:1 blend ratio of RCBP:RCGP, while a 20% RCBS replacement rate and extended curing periods markedly enhance strength. (2) Among the prediction models, GA-BP demonstrates superior performance, significantly outperforming BP models with both single and double hidden layer. (3) The functional extremum optimization results exhibit high consistency with experimental validation, showing a relative error below 10%, confirming the method’s effectiveness and engineering applicability. Full article

The construction industry’s escalating environmental footprint, coupled with the underutilization of construction waste streams, necessitates innovative approaches to sustainable material design. This study investigates the dual functionality of recycled clay brick powder (RCBP) as both a supplementary cementitious material (SCM) and an alkali–silica reaction (ASR) inhibitor in hybrid mortar systems incorporating recycled glass (RG) and recycled clay brick (RCB) aggregates. Leveraging the pozzolanic activity of RCBP’s residual aluminosilicate phases, the research quantifies its influence on mortar durability and mechanical performance under varying substitution scenarios. Experimental findings reveal a nonlinear relationship between RCBP dosage and mortar properties. A 30% cement replacement with RCBP yields a 28-day activity index of 96.95%, confirming significant pozzolanic contributions. Critically, RCBP substitution ≥20% effectively mitigates ASRs induced by RG aggregates, with optimal suppression observed at 25% replacement. This threshold aligns with microstructural analyses showing RCBP’s Al³⁺ ions preferentially reacting with alkali hydroxides to form non-expansive gels, reducing pore solution pH and silica dissolution rates. Mechanical characterization reveals trade-offs between workability and strength development. Increasing RCBP substitution decreases mortar consistency and fluidity, which is more pronounced in RG-RCBS blends due to glass aggregates’ smooth texture. Compressively, both SS-RCBS and RG-RCBS mortars exhibit strength reduction with higher RCBP content, yet all specimens show accelerated compressive strength gain relative to flexural strength over curing time. Notably, 28-day water absorption increases with RCBP substitution, correlating with microstructural porosity modifications. These findings position recycled construction wastes and glass as valuable resources in circular economy frameworks, offering municipalities a pathway to meet recycled content mandates without sacrificing structural integrity. The study underscores the importance of waste synergy in advancing sustainable mortar technology, with implications for net-zero building practices and industrial waste valorization. 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

Lead–zinc tailings are waste materials generated from mineral processing and smelting, and their long-term accumulation poses potential threats to the environment and soil. To achieve resource recycling and sustainable development, this study used lead–zinc tailings and clay as raw materials and glass powder as a modifier to prepare modified lead–zinc tailing sintered bricks. Through full-factor experiments and single-factor experiments, the effects of the material proportions, the sintering temperature, and the holding time on the properties of the sintered bricks were investigated. The results show that the addition of glass powder significantly enhanced the compressive strength of the sintered bricks, reduced their water absorption rate, and improved their volume shrinkage rate. The optimal preparation conditions were as follows: 9% glass powder content, 90% lead–zinc tailings content, a sintering temperature of 1060 °C, and a holding time of 60 min. The resulting sintered bricks met the MU30-strength-grade requirements of the national standard for ordinary sintered bricks (GB/T5101-2017). The sintering temperature has a significant impact on brick performance; the compressive strength first increases, and then decreases, the water absorption rate continues to decrease, and volume change shifts from expansion to contraction. The influence of holding time was relatively weaker, but as the holding time increased, the compressive strength and the water absorption rate of the sintered bricks gradually stabilized. XRD and SEM analyses indicated that the minerals in the lead–zinc tailings decomposed and recrystallized during the sintering process. The liquid phase melt from the glass powder filled the pores and enhanced skeletal strength, thereby improving the microstructure and properties of the sintered bricks. The research findings provide a theoretical basis and practical guidance for the efficient utilization and building material application of lead–zinc tailings. Full article

The availability of industrially used supplementary cementitious materials (SCMs, e.g., fly ash) decreases due to the rise in renewable energy sources and recycling technologies. Therefore, it is essential to find alternative SCMs (e.g., waste glass and clay brick powder) that are locally available. Accordingly, in this paper, the mechanochemical activation of clay brick waste (CBW) with abrasive glass powder (GP) and its pozzolanic reactivity are investigated. The mixtures of CBW and GP in mass ratios of 100:0, 75:25, 50:50, and 25:75 were mechanochemically activated for 15, 30, 45, and 60 min. The physical, chemical, and structural changes of the mixtures were examined by X-ray diffractometry, Fourier-transform infrared spectroscopy, scanning electron microscopy, and specific surface area measurements. The pozzolanic reactivity was characterized by the active silica content and the 28-day compressive strength of the binders (a mixture of ordinary Portland cement and activated material). The addition of GP favorably reduced the agglomeration and increased the active silica content of the activated mixtures (e.g., by 7–37% m/m at 15 min of mechanochemical activation). The 60 min of mechanochemical activation and the addition of 50% m/m of GP can increase the compressive strength by approximately 8%. Economically, the addition of 50% m/m of GP was found to be favorable, where only 30 min of mechanochemical activation resulted in a considerable increase in strength compared to that of the ordinary Portland cement. Full article

The application of geopolymers has recently been given significant attention to address climate change and the growing scarcity of construction materials in the 21st century. Researchers have utilized industrial waste or supplementary cementitious materials containing high levels of silica and alumina as precursors along with different alkaline activators. Furthermore, the technical challenges associated with waste brick management or recycling include both land use changes and financial implications. The existence of amorphous aluminosilicates in waste clay bricks, which can be used as geopolymer binders, has drawn attention recently. This paper reviews the recent advancements of the integration of clay brick wastes in geopolymer applications, individually as well as its use with other alternative materials. Prior studies suggest that waste clay bricks can effectively serve as the primary source material in geopolymer applications. This review covers various aspects, including the assessment of fresh, mechanical, microstructure, and durability-related properties. It specifically focused on enhancing these properties of waste clay bricks through mechanical and thermal treatments, through varying curing conditions, utilizing different types of alkaline activators, and considering their properties and corresponding ratios in the development of geopolymer products using waste brick powder. Furthermore, this paper portrays a critical review of the sustainability implications of the utilization of clay brick waste in geopolymer applications. Conclusively, this review provided the lessons learnt, research gaps, and the future direction for investigation into the feasibility of geopolymers derived from waste clay brick powder. Full article

Steel slag and waste clay brick are two common solid wastes in industrial production, and their complex chemical compositions pose challenges to the production of traditional alumina silicate ceramics. To investigate the influence of steel slag and waste clay brick on the performance of CaO–SiO₂–MgO ceramic materials, this study examined their effects on the mechanical properties, crystal composition, and microstructure of the ceramics through single-factor experiments. The results demonstrate that when keeping the dosage of waste clay brick and talcum powder constant, a 43% dosage of steel slag yields optimal performance for the ceramic materials with a modulus of rupture of 73.01 MPa and a water absorption rate as low as 0.037%. Similarly, when maintaining a constant dosage of steel slag and talcum powder, a 41% dosage of waste clay brick leads to superior performance of the ceramic materials, with a modulus of rupture reaching 82.17 MPa and a water absorption rate only at 0.071%. Furthermore, when keeping the dosage of steel slag and waste clay brick constant, employing a talcum powder dosage of 24% results in excellent performance for the ceramic materials with a modulus of rupture measuring 73.01 MPa while maintaining an extremely low water absorption rate at only 0.037%. It is noteworthy that steel slag contributes to akermanite phase formation while talcum powder and waste clay brick contribute to diopside phase formation. Full article

The global focus on geopolymer binder production has increased due to the adoption of waste materials and industrial byproducts. Given the gradual decline in the availability of fly ash and ground granular blast furnace slag (GGBFS) resulting from the decarbonization process in electricity and steel production, waste clay brick powder (WCBP) could be a viable substitute for these pozzolanic by-products. This study presents the economic and environmental benefits of the use of WCBP as a replacement for conventional pozzolanic by-products in geopolymer binder production by assessing its techno-eco-efficiency, environmental impact, and cost-effectiveness performances. The favorable mechanical characteristics exhibited by the fly ash–GGBFS–WCBP-based geopolymer binder emphasize the importance of assessing its sustainability alongside its technical viability. The study employed life cycle analysis (LCA), following ISO framework, and using the Simapro software 9.2, to evaluate the environmental implications of the use of WCBP-based geopolymer mixtures. Human toxicity emerged as the primary impact. Moreover, the analysis of life cycle costs highlighted key financial factors, with around 65–70% attributed to alkaline activators of the total cost. The production of alkaline activators was identified as a critical point for both environmental impact and economic considerations due to energy consumption. While WCBP-rich samples exhibit a 1.7–0.7% higher environmental impact compared to the control mix (CM), their high mechanical strength and cost-effectiveness make them technologically and economically efficient geopolymer mixes. In conclusion, the portfolio analysis for techno-eco-efficiency affirms that mixes containing 40%, 30%, and 20% WCBP are more efficient than those using 10% and 0% WCBP, respectively. Full article

Herein, we conducted an experimental test on basalt fiber-reinforced concrete with a high content of construction and demolition waste and then established some mathematical models based on Taylor’s formula. The concrete was prepared by using recycled clay brick powder in place of cement and recycled coarse aggregates as a substitution for natural coarse aggregates. The basalt fiber in weight dosages of 0, 0.1, 0.3, and 0.5% was used for reinforcement. The results showed that the compressive strength of concrete declined as the content of recycled aggregates increased, while the compressive strength first increased and then decreased as the basalt fiber dosage lifted. Regarding the splitting tensile strength, the reinforcement effect of basalt fiber in concrete with a high content of recycled aggregate is more significant when compared to its to its counterpart, which contains no or fewer recycled aggregates. The concrete with 0.5% basalt fiber dosage and 100% recycled aggregate content retains an equivalent compressive strength as to that of natural aggregate concrete and has about a 90% splitting tensile strength. In addition, the cubic function in comparison to the quadratic function has a higher fitting accuracy. Full article

The incorporation of construction and demolition (C&D) waste in concrete production has gained great importance toward sustainability, especially in geopolymer concrete. In this study, ground granulated blast-furnace slag (GGBFS) and fine aggregate of normal geopolymer concrete were partially replaced by clay brick powder (CBP) and fine clay brick (FCB) derived from C&D waste, respectively, aiming to produce high-strength geopolymer concrete (HSGC). Fly ash (FA) was also used as a partial replacement for GGBFS in normal geopolymer concrete. Twenty HSGC mixtures were designed using the response surface methodology with three variables, including CBP (0–25%), FA (0–25%), and FCB (0–50%). The performance of the proposed HSGC mixtures was assessed by measuring several mechanical and durability properties. In addition, a variety of physicochemical methods, including X-ray fluorescence spectroscopy, X-ray diffraction, and scanning electron microscopy, were used to examine the mineralogical and microstructural characteristics of the control and the developed mixtures. The findings revealed that the compressive, splitting tensile, and flexural strengths of the HSGC made with C&D waste ranged from 38.0 to 70.3 MPa, 4.1 to 8.2 MPa, and 5.2 to 10.0 MPa, respectively. The results also indicated that the incorporation of FA is an essential parameter to eliminate the negative impacts of C&D waste addition on concrete workability. The optimal proportions for the HSGC were 5% for CBP, 5% for FA, and 40% for FCB, which were determined to generate the optimized HSGC with the highest mechanical performance, according to the verified models and optimization findings. The physicochemical analyses showed that the thick amorphous geopolymeric gel predominated the nonporous structure of the optimized HSGC, which had good mechanical characteristics. Furthermore, the anti-carbonation performance and freezing resistance of the optimal HSGC increased by 17.7% and 14.6%, respectively, while the apparent porosity decreased by 8.4%. Full article

In masonry construction, the most commonly used building unit all over the world is the burnt clay brick. Adding waste materials in certain percentages to these bricks helps in eliminating the environmental burden occurring in the form of excessive waste accumulation on open land sites, leading to sustainable and economical construction. This research program aimed to examine the feasibility of using waste marble powder (WMP) and sugarcane bagasse ash (SBA) in the manufacturing of clay bricks. WMP was collected from local marble cutting workshops, whereas SBA was prepared by burning the waste sugarcane obtained from various sugar mills in the local area. Brick specimens incorporating 5%, 10%, 15%, and 20% of hybrid WMP and SBA were prepared at a local brick kiln. Burnt clay bricks were transported to the laboratory, and their mechanical and durability properties were evaluated. A reduction in weight per unit area of brick specimens incorporating waste materials was observed, allowing them to be easily handled and transported. Decreased compressive strength was due to the addition of waste materials in comparison with conventional clay bricks. However, waste percentages up to 15% satisfied the criteria for the minimum compressive strength as per the Building Code of Pakistan (BCP). All tested samples showed flexural strength greater than 0.65 MPa. Tested bricks incorporating 10% and 20% of waste materials had water absorption values of 18% and 21%, respectively, which are higher than that of conventional clay bricks. Moreover, bricks incorporating waste materials exhibited a higher initial rate of absorption than conventional clay brick; therefore, such bricks need to be wet well before use in masonry construction. Brick specimens showed less than 1% weight loss, and bricks exhibited no signs of distress and cracking after 50 freeze-thaw cycles. A decrease in compressive strength was observed due to sulphate exposure. However, specimens with 10% waste materials still satisfied the minimum compressive strength requirement of BCP. Based on this study, it can be concluded that bricks with up to 10% hybrid waste materials (WMP and SBA) will assist in the environmental issues of these wastes, leading to more sustainable and economical masonry construction. Full article

This study provides a characterization of materials from wastes and outcrops of two inactive bauxite mines located close to Sant Joan de Mediona and Peramola, Spain. Mineralogy was determined via powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Thermal properties were measured via differential thermal analysis–thermogravimetry (DTA-TG) and gresification tests. The crystalline phases are medium-high crystalline kaolinite and variable amounts of illite, quartz, calcite, boehmite, hematite and rutile/anatase. DTA show two endothermic peaks produced by the dehydroxylation of minerals: the first peak, at 530–538 °C, belongs to boehmite; the second peak, at 535–568 °C, corresponds to kaolinite. An exothermic peak at 950–978 °C is associated with mullite crystallization. The optimal sintering temperatures obtained from the gresification curves (firing shrinkage and water absorption) were 970 °C for carbonate-poor, illite-rich clays; 1100 °C for illite- and carbonate-poor samples; and near 1190 °C for carbonate-rich materials. The carbonate-poor samples fired at 1300 °C contain sillimanite and mullite, and the carbonate-rich materials are rich in gehlenite, anorthite, and hedenbergite. The mineralogy of these materials is sufficient to obtain ceramic materials with suitable properties, but not their low plasticity. They could be used in the formulation of bricks or as part of mixtures to produce refractory ceramics. Full article

In this study, two types of cemented tailings backfill (CTB) were prepared by breaking up the waste clay bricks (WCB) from dismantled buildings and replacing part of the cement with brick powder and part of the tailings with brick aggregate. The mechanical properties of the modified CTB were investigated. The results showed that the strength of CTB with 10% brick powder content increased by 16.24% at the curing age of 28 days, while the content of 20% brick powder only decreased by 0.11%. The strength of the brick aggregate with less than 20% content can be increased at each curing age, and the strength of the 15% brick aggregate at the curing age of 7 d and 28 d is increased by 65.54 and 58.8%. The failure strain of the CTB-containing brick powder decreases with the extension of the curing time, and the failure strain of the CTB-containing brick aggregate decreases significantly at the curing age of 7 days. In addition, a three-stage damage constitutive model was established based on the results obtained in the present study, and the laboratory test results of CTB under uniaxial compression were effectively described with high confidence. Full article

Worldwide, vast amounts of waste are produced every year and most waste is sent directly to landfills or burnt, which has severe and harmful impacts on the environment. Recycling waste materials is considered the most visible solution to protect the environment. Using scraps in concrete production is a proper method for getting rid of wastes, improving the characteristics of concrete, reducing the consumption of natural aggregates, and can be used as cementitious materials that decrease cement production so that the CO₂ that is produced during cement manufacturing decreases. This review paper summarizes the use of recycled waste materials, including rubber tires, crushed glass, and crushed clay brick in concrete, as a fractional replacement of aggregates, cement, etc., to develop eco-friendly lightweight construction materials. It has been concluded that the dry density of sustainable concrete decreased to 4, 21.7, and 31.7% when crushed glass, clay brick, and rubber tire were incorporated into the concrete instead of traditional aggregate, respectively. Waste rubber has good results in sulfate, thermal, and impact resistance, while glass powder and finely crushed clay brick helped to improve mechanical properties by increasing reach by 33% for glass and a slight increase for crushed clay brick, as well as thermal resistance compared to normal concrete. Moreover, due to the low particle density of these waste materials compared to that of normal-weight aggregates, these materials can be utilized efficiently to produce lightweight concrete for structural and non-structural applications such as road engineering, flooring for mounting machinery, highway and rail crash barriers, permeable pavement, interlocking bricks, insulation, filling concrete, and bearing walls. Full article