Optimization via Taguchi of Artificial Lightweight Aggregates Obtained from Kaolinite Clay and Ceramic Waste: Develop-ment and Industrial Applications.

Abstract

Lightweight artificial aggregates (LWAs) are widely used in civil construction, but their conventional production depends on pure clays, a finite natural resource that negatively impacts the environment. This study aims to contribute to minimizing this issue by exploring the use of sustainable ternary mixtures of kaolinitic clay (KC), chamotte residues (CHT), and eucalyptus firewood ash (EFA), promoting a more environmentally friendly approach to the manufacture of LWAs. Thus, the aim was to develop and optimize LWAs using different replacements of industrial waste. Furthermore, the Taguchi method is employed to identify the optimal manufacturing parameters, such as waste content, sintering temperature, and heating time. The research involved the production of 32 distinct mixtures with different proportions of KC, CHT, and EFA, processed through grinding and sintering at temperatures ranging from 1075 ◦C to 1180 ◦C. The samples were evaluated for density, water absorption, mechanical strength, and expansion index. Statistical analysis was conducted using ANOVA to validate the most significant factors. The results revealed that mixtures with 80% of waste presented an aggregate expansion index of up to 60%, a minimum bulk density of 1.20 g/cm3 (which aligns with requirements for structural applications but exceeds the maximum bulk density for some lightweight aggregates), and crushing strength higher than 5 MPa, satisfying the normative criteria for commercial LWAs. In addition, 63 industrial applications were identified for the developed materials, ranging from structural lightweight concretes to thermal and acoustic insulation with varied microstructures. Therefore, the partial replacement of clay by CHT and EFA waste represents a promising alternative for producing sustainable LWAs, helping to reduce environmental impacts while providing quality materials for various applications in the most diverse industrial sectors.