Abstract
This study investigates the potential of burnt clay shale (BCS) from the Mynaral deposit (Zhambyl region, Kazakhstan) as an active mineral additive in composite cements and arbolite. Thermal and X-ray diffraction analyses revealed progressive dehydration, decarbonation, and decomposition of kaolinite, chlorite, and calcite, with optimal activation at 900 °C. Pozzolanic activity tests confirmed maximum reactivity at this temperature. Mechanical testing showed that 10–15% BCS increased cement strength up to 51 MPa, while higher dosages reduced performance. Arbolite samples with ash-and-slag binders and controlled alkaline additives demonstrated superior density and strength, supported by SEM evidence of dense crystalline microstructures and strong binder–filler adhesion. The findings highlight BCS as an effective, eco-friendly component reducing clinker consumption and CO2 emissions.