Thermal Performance of Ceramic Building Materials: The Influence of Clay Matrix and Organic and Inorganic Waste—A Review

Abstract

This review evaluates how clay mineralogy, waste composition, and processing conditions govern the thermal, physical, and mechanical performance of fired clay ceramics containing organic and inorganic residues. Following PRISMA 2020, 125 original studies published between 2000 and 2025 were selected from Scopus and Web of Science. Keyword co-occurrence analysis and relative-change matrices were used to examine research trends and variations in apparent porosity, water absorption, bulk density, compressive strength, and thermal conductivity. Organic residues generally promoted pore formation, reduced density, and lowered thermal conductivity, but these changes were often accompanied by proportionally greater losses in compressive strength. Inorganic residues showed more heterogeneous responses because they may act as pore-forming, fluxing, filler, or phase-forming components, depending on their chemical composition, interaction with the clay matrix, and firing conditions. The results confirm that total porosity or residue content alone cannot predict thermal performance, since pore geometry, connectivity, phase development, and solid-matrix continuity also govern heat transfer and mechanical behavior. Relative-change matrices summarized net property trajectories within each experimental configuration, and intermediate incorporation levels were considered when they altered the apparent thermal–mechanical balance. Technically suitable formulations must balance thermal insulation, mechanical integrity, moisture stability, processing reproducibility, durability, and environmental safety.