Optimizing the Thermal Treatment of Mining-Waste-Amended Clays for Ceramic Aggregates in Pavement Applications

Mining activities generate large volumes of tailings with significant environmental impact but also the potential for sustainable reuse in construction materials. This study evaluates the production of ceramic aggregates from mixtures of clay, sand, and iron ore waste subjected to thermal treatment at temperatures ranging from 600 to 1100 °C. The influence of calcination temperature on mineralogical transformations and mechanical integrity was investigated using X-ray diffraction (XRD) and the α-Treton parameter, derived from standardized impact resistance testing. The results indicate that the formation of metakaolinite between 700 and 900 °C enhances mechanical resistance, while higher temperatures (>900 °C) lead to structural degradation, followed by partial recovery due to mullite crystallization. The α-Treton curve exhibited clear correlation with the phase changes identified by XRD, demonstrating its applicability as a low-cost, sensitive proxy for optimizing thermal activation. A simplified methodology is proposed to optimize the thermal activation of such materials by correlating firing temperature with mineralogical evolution and mechanical integrity, contributing to the development of sustainable ceramic aggregates for pavement applications.