Enhancing the sustainable production of cost-effective ceramics with high strength using kaolin, sewage sludge and blast-furnace slag

Solid waste treatment remains an unavoidable environmental burden for modern cities. Currently, the multipurpose utilization of solid waste in construction and building materials is worth in-depth research as it furnishes high-value commercialization pathways with environmental and economic benefits for managing waste and addressing resource scarcity. This study explored the cost-effective ceramic fabrication from 40 % sewage sludge, 10 % blast-furnace slag and 50 % kaolin through in-situ sintering method, which enhanced the sustainable production of ceramic materials. The influences of firing temperature on the ceramic sintering effects, including mineral composition, micromorphology, pore structure and process performance, were systematically investigated. Results showed that the particle consolidation and sintering degrees of finished ceramics continuously increased as the firing temperature raised, presenting different surface, cross-sectional and pore structure characteristics. This was because increasing the firing temperature changed natures of the formed glass phase, such as content and viscosity. Moreover, variations in the ceramic structure would further affect its process performance. The ceramics prepared at 1250 degrees C were determined to have best firing effects with the densest structure and excellent performance, and the corresponding water absorption, bulk density, apparent porosity and compressive strength were 0.97 %, 2.32 g/cm3, 2 % and 70 MPa, respectively. Finally, comparisons with other researches confirmed that the developed ceramics possessed strong competitiveness in process performance. The presented study provided data support for the value-added application and sintering optimization of waste slag and sludge in ceramic production.