Recycling Red Ceramic Waste as a Raw Material for Lightweight Aggregates

The growing demand for lightweight aggregates (LWAs) in the construction industry is driving the development of sustainable alternatives based on the reuse of solid industrial waste. The aim of this study was to assess the technical feasibility of using red ceramic waste (RCW) as a partial or total substitute for red clay (RC) to produce lightweight expandable aggregates. Six formulations were made with different proportions of RCW and RC and sintered at four temperatures (1100, 1150, 1200 and 1250 °C). They were characterised using physical, thermal, morphological, chemical and mechanical analyses, according to standard protocols. The results showed that almost all the formulations sintered at 1200 and 1250 °C had a positive bloating index (BI > 0), particle density of less than 2.0 g/cm3, low water absorption of less than 2% and mechanical strength of more than 5.4 MPa, revealing strong potential for use in lightweight structural and non-structural concrete. The main conclusion is that RCW, even used in isolation, has physicochemical and mineralogical properties suitable for the production of lightweight aggregates under optimised thermal conditions, contributing to the development of sustainable materials with a competitive technical performance compared to commercial LWAs.