Innovative use of Cariri stone waste for developing anorthite‐based porous ceramics

Abstract Cariri Stone is a type of limestone extensively quarried in the region of Cariri, Ceará (Brazil). However, its extraction process generates large volumes of waste—up to 70% of the total extracted material—which is often disposed of improperly, resulting in significant environmental impacts. This study explored the technical feasibility of incorporating Cariri stone waste (CSW) as an alternative raw material in porous ceramic formulations based on kaolin and alumina. Compositions were developed with CSW content ranging from 10% to 28%. Test specimens were shaped by uniaxial pressing (40 MPa) and subjected to sintering at temperatures of 1100°C, 1150°C, 1200°C, and 1250°C. The sintered specimens were characterized in terms of apparent porosity, bulk density, water absorption, mercury intrusion porosimetry, total porosity, linear shrinkage, and three‐point flexural strength. Microstructural aspects and thermal behavior were also evaluated. It was observed that compositions containing 21% and 28% of waste exhibited higher porosity, good dimensional stability, and flexural strength reaching values around 38 MPa. The anorthite was the predominantly crystalline phase. Mullite and gehlenite were also identified. The results demonstrated that CSW has the potential to produce sustainable and innovative porous ceramics with good dimensional stability and mechanical resistance.