Development of Sustainable Artificial Lightweight Aggregates with Binary Mixtures of Waste Rich in Aluminosilicate and Carbonate in Kaolinitic Clay

In Brazil, artificial lightweight aggregates (LWAs) are predominantly produced in the Southeast Region using clay as the primary raw material. However, clay extraction has significant environmental impacts and limits access to LWAs in the North and Northeast regions, resulting in high costs and hindering sustainable construction solutions. This study addresses these challenges by developing sustainable LWAs in the Northeast Region using raw materials from the metropolitan area of João Pessoa, Paraíba, namely chamotte (CHT), which is rich in aluminosilicates, and eucalyptus firewood ash (EFA), which is rich in carbonates, combined with kaolinitic clay (KC). Sixty-four binary mixtures were produced, demonstrating diverse properties in density, water absorption, and compressive strength. EFA-rich mixtures achieved the highest expansion (80%) and lowest density (1.20 g/cm3), while CHT-rich mixtures provided superior strength (>10 MPa) and deformation (>20 GPa). These properties highlight their suitability for diverse applications, from structural uses to landscaping, enhanced by distinct color variations. Statistical optimization identified the residue content and sintering temperature as key factors, confirming the technical viability of incorporating up to 80% industrial waste into sustainable LWA production. Therefore, the results confirm the technical feasibility of producing LWAs using CHT and EFA in the metropolitan region of João Pessoa/Paraíba, achieving properties comparable to commercial LWAs. By incorporating up to 80% industrial waste, this study reduces dependence on non-renewable resources, decreases CO2 emissions and transportation costs, and promotes sustainable practices. The findings offer a scalable, eco-friendly solution to resource-limited regions’ material scarcity.