This study investigates the effects of waste glass (GL) and silica fume (SF) on the physical, mechanical, and microstructural properties of clay-based ceramic materials produced from low-grade calcite-rich clay loam. Waste glass and silica fume were incorporated at 10–20 wt.%, and the specimens were fired at temperatures ranging from 1050 to 1150 °C. The average density, water absorption, compressive strength, phase composition (XRD), and microstructure (SEM) were evaluated. The results showed that waste glass significantly enhanced the sintering behavior of the ceramic body through liquid-phase formation at elevated temperatures. The average density increased from approximately 1650 to 2200 kg/m³, while water absorption decreased from 6.5% to 3.2%. The optimum firing temperature was 1125 °C, at which the ceramic compositions containing 10 wt.% and 15 wt.% waste glass exhibited no visible deformation and achieved compressive strengths of 32–36 MPa. In contrast, silica fume was less effective as a fluxing additive, resulting in lower strength, increased deformation, and cracking at temperatures above 1100 °C. SEM observations confirmed the formation of a denser, more homogeneous microstructure in the waste glass-modified specimens, while XRD analysis revealed a reduction in quartz content, accompanied by enhanced formation of the diopside and anorthite phases. Among all investigated compositions, the ceramic material containing 10 wt.% waste glass and fired at 1125 °C exhibited the most balanced combination of density, water absorption, and compressive strength, demonstrating its potential for producing high-performance clay-based ceramic materials.

Despite the large volumes of marbleized limestone processing waste (MLPW) generated by the stone industry, its utilization in the production of high-strength masonry materials remains limited, and systematic comparative studies of white and gray Portland cements in hyperpressed MLPW-based bricks are scarce. In this study, four mixture formulations containing MLPW (70–85 wt.%), white Portland cement (CEM I 52.5, M500) or gray Portland cement (CEM I 42.5, M450), and water were prepared at a constant water-to-cement ratio of 0.25. Specimens were manufactured by hyperpressing under compaction pressures of 28 and 41 MPa and cured for 7 days in a sealed moist environment. The formulations compacted at 28 MPa achieved compressive strengths corresponding to brick strength grades M350 and M400. Increasing the pressure to 41 MPa yielded grades M400–M550 with white cement; under identical conditions with gray cement, grades M400 and M450 were attained. Among the tested formulations, those containing 75–80 wt.% MLPW (20–16 wt.% cement) showed the most favorable combination of compressive strength and density. The mechanical performance correlated well with the microstructural features observed by scanning electron microscopy (SEM) and EDS analysis. The average density of all specimens exceeded 2100 kg/m³, classifying the materials as heavyweight concrete. The novelty of this work lies in the comparative evaluation of white and gray Portland cements in hyperpressed MLPW bricks and the establishment of relationships between compaction pressure, binder type, overall mixture composition, and resulting strength grades. The results demonstrate a promising route for converting high volumes of industrial marble waste into high-strength masonry units. However, further investigation of durability-related parameters, including water absorption, frost resistance and flexural strength, is required before the practical application of the developed materials can be fully evaluated.

This study presents a comparative evaluation of natural clays from the Koksay (K-Cl), Shemolgan (S-Cl), and Uzynagash (U-Cl) deposits in the Almaty region of Kazakhstan, followed by a detailed investigation of the firing behavior of K-Cl. The raw materials were characterized in terms of physical and technological properties, particle-size distribution, and chemical composition. The three clays exhibited similar oxide compositions dominated by SiO₂ (62.81–63.41 wt.%), Al₂O₃ (13.57–13.77 wt.%), and relatively high CaO contents (10.38–10.94 wt.%). K-Cl was selected for firing at 1050, 1100, and 1150 °C based on the combined raw-material screening results. Limited densification occurred at 1050 and 1100 °C. Firing at 1150 °C increased the fired density to 2221 kg/m³, linear shrinkage to 10.10%, and compressive strength to 54.21 MPa, while water absorption decreased to 3.9%. XRD analysis revealed substantial reorganization of the crystalline assemblage, including an increase in the relative contribution of hedenbergite from 28% to 50% between 1100 and 1150 °C. SEM–EDS observations showed the development of a more consolidated microstructure at the higher firing temperature. Overall, the results indicate the potential of K-Cl as a local raw material for dense fired construction ceramics and identify 1100–1150 °C as a promising range for further optimization of the firing conditions.

Marbleized limestone processing waste (MLPW) was used as the primary raw material in this study. White Portland cement (CEM I 52.5, M500) and gray Portland cement (CEM I 42.5, M450) were employed as binders. The mixtures were prepared with an MLPW content ranging from 70 to 85 wt.% while maintaining a constant water-to-cement ratio (w/c) of 0.25. The specimens were manufactured by hyperpressing under compaction loads of 200 and 300 kN and subsequently cured for 7 days in a sealed moist environment. Specimens compacted at 200 kN achieved compressive strengths corresponding to brick strength grades M350 and M400. Increasing the compaction load to 300 kN resulted in specimens meeting the requirements of strength grades M400 and M500. When gray Portland cement (M450) was used as the binder at identical MLPW contents and water-to-cement ratio, specimens compacted at 300 kN attained compressive strengths corresponding to grades M400 and M450. The mechanical performance of the hyperpressed bricks produced with both white and gray Portland cement correlated well with the microstructural characteristics observed by scanning electron microscopy (SEM). The average density of all specimens exceeded 2100 kg/m³, allowing the developed materials to be classified as heavyweight concrete. The study aims to develop optimized compositions and a manufacturing technology for hyperpressed bricks based on marbleized limestone processing waste, thereby promoting the sustainable utilization of industrial by-products in the production of high-performance masonry materials.