Search Results (20)

The integration of salt removal and structural consolidation remains a major challenge in heritage brick conservation. This research proposes a preliminary experimental setup for a dual-function microbial strategy using a single bacterium, Stutzerimonas stutzeri D1, capable of sequential denitrification (biocleaning) and ureolysis-driven microbially induced calcium carbonate precipitation (biocementation). After the pre-check assessment, which compared standalone, simultaneous, and sequential metabolic configurations, sequential denitrification followed by ureolysis (A→B) optimized functional compatibility, achieving 90.1% nitrate removal within 48 h and the highest precipitation rate during the biocementation phase. Application on authentic demolition waste (solid fired-clay brick specimens) demonstrated highly efficient nitrate reduction, alkalization (from pH value of 6.4 to 9.12), surface mineral deposition confirmed by visual inspection, SEM imaging, and XRD analysis. Furthermore, reduced water absorption (by 30%) and improved compressive strength (by 25%) for only 72 h of this dual treatment indicate a promising and holistic approach in the field of construction biotechnology of heritage brick conservation. These pioneer findings demonstrate that metabolic sequencing governs compatibility in dual-function bacterial systems and validate a sustainable, single-strain platform for combined biocleaning and biocementation of historic brick masonry structures. Full article

Refractory geopolymers derived from aluminosilicate sources and alkaline activation are a promising alternative to traditional fired bricks, particularly when low-cost, waste-derived raw materials are used. This study improves the workability of a refractory brick formulated with clays (Kaolin and Tepozan–Bauwer), seashell waste, sodium silicate, potassium hydroxide, and water by incorporating sodium lignosulfonate (LS) and polycarboxylate (PC) plasticizers. Clays from Comonfort, Guanajuato, Mexico, and seashells were ground and sieved to pass a 100 Tyler mesh. A base mixture was prepared and evaluated using the Mini Slump Test, varying plasticizer content from 0 to 2% relative to the solid fraction. Based on workability, 0.5% LS and 1% PC (by solids) increased the slump, and a blended plasticizer formulation (1.5% by solids, 80%PC+20%LS) produced the highest workability. These additives act through different mechanisms, with LS primarily promoting electrostatic repulsion and PC steric repulsion. Bricks with and without plasticizers exhibited thermal resistance up to 1200 °C. After four calcination cycles, compressive strength values were 354.74 kg_f/cm² for the brick without plasticizer, 597.25 kg_f/cm² for 1% PC, 433.63 kg_f/cm² for 0.5% LS, and 519.05 kg_f/cm² for 1.5% of the 80%PC+20%LS blend. Strength was consistent with changes in porosity and apparent density, and 1% PC provided a favorable combination of high workability and high compressive strength after cycling. Because the cost of clays and seashells is negligible, formulation selection was based on plasticizer cost per brick. Although 1% PC and the 1.5% of 80%PC+20%LS blend showed statistically comparable strength after cycling, 1% PC was selected as the preferred option due to its lower additive cost ($0.0449 per brick) compared with the blend ($0.0633 per brick). Stereoscopic microscopy indicated pore closure after calcination with no visible cracking, and SEM–EDS identified O, Si, and Al as the significant elements, with traces of S and K. Overall, the study provides an integrated assessment of workability, multi-cycle calcination, microstructure, and performance for refractory bricks produced from readily available clays and seashell waste. 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

The conversion of the waste of wet silica sand sludge (W3S) into useful products, such as bricks, glassware, and ceramics, is an alternative solid waste management method. The aim of this study is to determine the effect of silica sand wet sludge additive on brick quality. For this purpose, laboratory-scale brick manufacturing was implemented by using 10%, 30%, 50%, and 100% sludge in clay brick. For proper characterization to understand brick quality, the water absorption, shrinkage, bulk density, compressive strength, and SEM analysis of sintered samples were performed. At the end of the experimental procedure, no negative effects of sludge addition were determined in terms of mechanical strength, porosity, water absorption, or structural integrity. In addition, the incorporation of W3S contributed to sustainable waste management and helped mitigate its environmental impact. Experimental studies revealed that a product with the desired color could be obtained when 50% W3S was used in the mixture. In addition, the optimal composition for making bricks was found to be a mixture of 50% W3S and 50% brick clay, fired at 850 °C. With this mixture, not only is the preferred color achieved, but an optimum balance between mechanical strength, durability, and minimization of environmental damage is also attained. Such a formulation ensures high compressive strength, low porosity, and low water absorption, making it sustainable and a better choice in construction with industrial by-product use. The results obtained are useful in showing possibilities for the solution of environmental problems to utilize waste materials in useful products. Full article

Traditional bricks are still the most widely used building material in Madagascar. Bricks are made from clay that is fired for weeks in open-air kilns (600–750 °C) by using rice husks, peat, charcoal, coal, and wood as fuels. This process contributes significantly to environmental pollution by emitting CO₂ and particles. In addition, the intensive use of wood and charcoal is partly responsible for the deforestation that still taking place on the “Red Island”. The development of sustainable building materials is therefore of global interest. This research provided a solution by implementing the oxyacetic acid derivative of cashew nut shell liquid (CNSL) as a binder to reduce energy consumption in the preparation of earthen materials. This product was obtained from cashew nut waste and was used in a proportion of 5 to 15% with the red soil of Madagascar. The materials were formulated at a much lower temperature (60 °C) compared to the traditional process for 24 to 48 hours in a custom-designed mold. The material with 10% oxyacetic binder from CNSL was a compact, hard solid with higher mechanical properties, including a twice higher compressive strength (5.6 MPa compared to 2.2 MPa) and a higher tensile strength (2.2 MPa compared to 1.6 MPa). This material also had better water resistance after 2 months of immersion; traditional clay bricks absorbed 36.65% of the water, and the material with binder only absorbed 12.62%. This research demonstrates that the utilization of local agricultural waste as a binder is a viable strategy for reducing the carbon footprint of traditional building materials while significantly improving their physico-mechanical properties. Full article

This study examines the reduction in energy consumption in residential and commercial buildings by utilizing eco-efficient ceramic bricks, converted into building blocks for the construction industry, in light of their significant energy usage and the challenges associated with solid waste management. A ceramic brick composed of zeolite and sugarcane bagasse ash (ZS brick) was selected and simulated as a building block. Such building blocks were used in building design models, and annual building energy simulation was performed by applying different approaches and modes. The results in four different climatic regions in Iran proved that the use of ZS bricks in building envelopes without a thermal insulation layer could lead to a reduction in building energy consumption from 5 to 12.5% compared with conventional fired clay bricks. Also, the use of ZS brick in the layering of the building walls with a thermal insulation layer, compared with conventional fired clay bricks, resulted in an energy consumption reduction from 2.3 to 7.5%. Full article

This research suggested natural hemp fiber-reinforced ropes (FRR) polymer usage to reinforce recycled aggregate square concrete columns that contain fired-clay solid brick aggregates in order to reduce the high costs associated with synthetic fiber-reinforced polymers (FRPs). A total of 24 square columns of concrete were fabricated to conduct this study. The samples were tested under a monotonic axial compression load. The variables of interest were the strength of unconfined concrete and the number of FRR layers. According to the results, the strengthened specimens demonstrated an increased compressive strength and ductility. Notably, the specimens with the smallest unconfined strength demonstrated the largest improvement in compressive strength and ductility. Particularly, the compressive strength and strain were enhanced by up to 181% and 564%, respectively. In order to predict the ultimate confined compressive stress and strain, this study investigated a number of analytical stress–strain models. A comparison of experimental and theoretical findings deduced that only a limited number of strength models resulted in close predictions, whereas an even larger scatter was observed for strain prediction. Machine learning was employed by using neural networks to predict the compressive strength. A dataset comprising 142 specimens strengthened with hemp FRP was extracted from the literature. The neural network was trained on the extracted dataset, and its performance was evaluated for the experimental results of this study, which demonstrated a close agreement. Full article

This paper discusses the integration of an alkali-activated mortar (AAM), based on industrial waste, into a novel composite material fit for structural upgrading purposes and rendered with high temperature endurance and a low CO₂ footprint. The AAM combined with carbon fiber textiles form a new generation of sustainable inorganic matrix composites—that of textile-reinforced alkali-activated mortars (TRAAM). A test program was designed to assess the effectiveness of carbon TRAAM overlays in increasing the shear capacity of masonry wall specimens comprising solid clay bricks bonded with lime-based mortar and furnished with TRAAM jackets on both sides. The initial and the residual capacity of the reinforced walls were evaluated, the latter by performing diagonal compression tests after exposure to 300 °C and 550 °C. It was shown that TRAAM jacketing can increase the shear capacity of unfired masonry walls by 260% and 335% when a single or a double layer of textile is used, respectively. Rapid heating to temperatures up to 550 °C, one-hour-long steady-state heating, and natural cooling bore no visible thermal cracks on the specimens and had little effect on their residual capacity. Based on these results, the prospect of using TRAAM for retrofitting applications for fire-resilient structures seems very auspicious. Full article

Each year, an enormous amount of construction waste is produced worldwide. The reuse of construction waste in construction works is a sustainable solution. The present research work utilized recycled brick aggregates in the production of concrete. The resulting concrete exhibited substandard splitting tensile, flexural, and compressive properties. Steel fibers were used to improve these substandard properties of recycled brick aggregate concrete. The volume fractions of 1%, 2%, and 3% for steel fibers were mixed in concrete, whereas recycled brick aggregates were obtained from solid fired-clay bricks, hollow fired-clay bricks, and cement–clay interlocking bricks. The compressive strength was enhanced by up to 35.53% and 66.67% for natural and recycled brick aggregate concrete, respectively. Strengthened flexural specimens demonstrated up to 8765.69% increase in the energy dissipation. Specimens strengthened with steel fibers showed substantially improved splitting tensile, flexural, and compressive responses. Separate equations were proposed to predict the peak compressive strength, strain at peak compressive strength, elastic modulus, and post-peak modulus of recycled brick aggregate concrete. The proposed regression equations were utilized in combination with an existing compressive stress–strain model. A close agreement was observed between experimental and predicted compressive stress–strain curves of recycled brick aggregate concrete. Full article

The thermal insulation properties of building walls are critical to the overall energy efficiency and comfort of a building. One important factor that can affect these properties is the type of bricks used in construction. Bricks can vary in their geometry and thermal coefficient, which can impact their ability to transfer heat through the wall. The geometry of a brick can affect its thermal properties by altering the amount of air trapped within it and the surface area available for heat transfer. Hollow bricks or those with complex geometries may have lower thermal conductivity than regular solid bricks due to the air pockets trapped within them. Conversely, larger surface areas on the exterior of the brick can increase heat transfer. The thermal coefficient of clay, a common material used in brick production, is another important factor. Clay has relatively low thermal conductivity, meaning it is a poor conductor of heat. However, the quality of the clay, as well as the firing temperature and duration used in brick production, can impact its thermal coefficient. Higher firing temperatures and longer firing times can result in a more compact and dense clay brick, which can improve its thermal properties. In summary, the thermal insulation properties of building walls can be significantly affected by the type of bricks used in their construction. It is important to consider the geometry and thermal coefficient of the bricks when designing a building to achieve the desired level of thermal insulation. By selecting bricks with appropriate properties, designers can help to improve the energy efficiency and comfort of the building while reducing its environmental impact. Full article

Currently, the amount of man-made waste worldwide is steadily increasing. It is, therefore, necessary to constantly look for effective ways of utilization and recycling. It is also necessary to reduce the use of non-renewable resources and reduce the impact on the environment. The use of coal industry waste is currently quite insignificant, amounting to some 10% of the total volume. The work aimed to study the properties of raw materials and study the processes of structure formation during the forming, drying, and firing of composite ceramic produced using overburden rock and additives. The work’s relevance lies in the need to solve environmental, economic, and technological problems related to the utilization of coal mining waste. Experiments of the past prove the possibility of using the waste coal industry as additives in the production of building materials. The article presents the results of studies of the chemical, mineralogical, and granulometric composition of overburden rock in coal mining. Peculiarities of structure formation during the forming, drying, and firing of ceramic composites based on optimal fractional compositions from coal-mine overburden were revealed. Organic and chemical additives were used for the correction of technological properties and improvement of the quality of finished composite products. The physical and mechanical indices of the obtained composite ceramic samples were determined, the analysis of which revealed that the use of highly mineralized carbonaceous rocks as solid additives provided a 2–2.5-fold increase in the strength of the product, 5.6% reduction in water absorption, and an increase in the product frost resistance by 20–25 cycles. The aluminum oxychloride influence on the physical and mechanical indices of the obtained composite articles was reflected in a reduction in their water absorption from 8.2 to 7.0%, a 10–12% increase in strength in compression, and an increase in freeze–thaw resistance by 30–35 cycles. Research results proved that the composition and properties of coal-mine overburden rock are close to those of conventional clays. With special technological preparation, they can be used for the production of composite ceramic products. This will significantly reduce the cost of bricks, to make up for the shortage of high-grade clay raw materials and improve the environmental situation. Nevertheless, further research into the use of coal-mine overburdens in the composite ceramic material technology is warranted. Full article

This research explores the potential of using municipal solid waste incinerator bottom ash (MSWIBA) as a partial replacement for fine aggregate and ordinary Portland cement (OPC) as a stabilizer in the production of compressed stabilized earth blocks (CSEBs). The study investigates the effect of varying levels of cement content (ranging from 0% to 10%) and MSWIBA content (ranging from 0% to 25%) on the strength and durability of CSEBs. The strength characteristics of CSEBs were evaluated through tests such as wet and dry compressive strength, flexural strength, water absorption, and stress–strain behavior, while durability was tested through wetting–drying cyclic tests. The results indicated that CSEB blocks made with 20% MSWIBA content and 10% cement were able to fulfill strength criteria. Additionally, using these blocks could result in cost savings of 8% during construction when compared to using fired clay bricks (FCB). Furthermore, varying the cement content while maintaining a constant proportion of MSWIBA showed a significant change in the stress–strain behavior and a cost analysis performed for CSEBs stabilized with the optimal quantity of MSWIBA-OPC combination showed that they can be a viable alternative to conventional earth blocks, providing an eco-friendly, sustainable, and cost-effective solution for construction initiatives. Full article

In this work, the recovery of valuable metals from Bayer red mud using hydrometallurgical techniques and the subsequent use of the solid remaining after leaching as the principal component of the fired bricks were analyzed. Water, sulfuric acid, and sodium hydroxide were used as leaching agents. Different L/S ratios and contact times were also tested. According to technical, economic, and environmental considerations, the optimal conditions to recover valuable elements from red mud were 2 M H₂SO₄, in contact for 24 h, with an L/S ratio = 5. Under these conditions, high leaching yields of valuable elements such as La (47.6%) or V (11%) were achieved. After the leaching process, the remaining solid was mixed with clay and water to produce bricks. Two doses of red mud (50 and 80% w) and two different sintering temperatures (900 and 1100 °C) were tested. When the proportion of treated RM in the mix was increased, the compressive strength of the bricks was reduced, but it was increased as the sintering temperature was increased. The environmental safety of the bricks manufactured (leaching of heavy metals and radionuclides) was also studied, and it was found that it was more favorable when red mud was treated instead of fresh red mud being used. Full article

The advent of new materials and technologies in building materials has changed the way of building. New lighter materials with easier application methods and improved mechanical behaviors, have become necessary for the market. Moreover, the new environmental policy (2022) aims to transform the waste management into sustainable materials management to ensure the long-term protection and improvement of the environment. For the brick and tile industry, raw materials and the additives that compose the product mixture seem to be a key factor in this direction. Furthermore, every product type (solid or perforated brick) requires different additives to achieve the properties that are postulated by the international standards. For the study, the wide range of additives that were used have been assorted into three (3) categories: the inert materials, the lightweight materials, and the industrial remains. Totally, eight (8) different materials were used as additives into ceramic mass, in different proportions each time. Almost all additives used for this research were pore-forming agents. These burn out almost completely before reaching the full-fire temperature, and do not change the fired body. As a result of additives burnt out, the necessary pore volume is formed in the fired brick body, which, if combined with an appropriate percentage of voids, result in raw density readings. The pore structure is significant as long as the ultimate strength of lightweight bricks is acceptable. In this study, additives between 3 and 25% by weight were added to the clay mixture. The extrusion of specimens in solid form was carried out using the Laboratory’s vacuum press. Firstly, the extrusion of specimens from the original raw material was implemented. Secondly, it was made on the material mixed with the additives mentioned above. A series of experimental activities were followed to determine the variations of the mechanical and physical properties as well as their production procedures (extrusion, drying, and firing). According to five (5) key properties measured in the current study and compared with the mixture without additives, it was found that the variation in thermal conductivity improvement is between -11% and 19%. The bending strength of the fired products showed a decrease from 16% to 55% except for the addition of bauxite residue, which increased the strength by 8%. Bigot drying sensitivity decreased from 11% to 27%. The density in two cases increased from 2% to 7% while in the majority the mixtures with the additives showed a decrease in density from 1% to 14%. Finally, the addition of the necessary water for shaping during extrusion showed a variation from a 10% decreased to a 14% increased water. Full article

The permeable pavement system (PPS) has effectively contributed to stormwater management as a low-impact development (LID) technology. The suitability of clay bricks, consolidated with waste materials, for sustainable PPS applications in urban infrastructure needs further attention. In this study, several series of permeable clay paving bricks samples were prepared by mixing different ratios and particle sizes of sawdust (SD) with clay soil and firing at 900 °C. The raw soil and SD samples were characterized through sieve analysis, X-ray Fluorescence (XRF), X-ray diffraction (XRD), and Fourier-Transform Infrared Spectroscopy (FTIR). The bricks were tested for their compressive strength, bulk density, apparent porosity, water adsorption, permeability coefficient, and stormwater treatment efficiency. The clay soil comprised 17.5% clay/silt with appropriate amounts of SiO2 (50.47%), Al2O3 (19.14%), and fluxing agents (15.34%) and was suitable for brick manufacturing. XRD and FTIR analysis revealed that the soil predominantly comprises quartz, dolomite calcite, feldspar, kaolinite, illite, and chlorites. The SD samples were enriched with amorphous and crystalline cellulose. The compressive strength of the bricks decreased, while the permeability of the bricks increased with an increasing percentage of SD. An optimal percentage of 10% SD achieved a 21.2 MPa compressive strength and a 0.0556 m/s permeability coefficient, meeting the ASTM specifications for PPS. The optimal size of SD, between 0.5 and 1.0 mm, achieved the desired compressive strength of the bricks. The permeable bricks effectively removed the total suspended solids (TSS), turbidity, and BOD5 from the stormwater, which complies with the guidelines for wastewater reuse applications. Full article