Development of lightweight and thermally efficient clay bricks using expansion additives: effects of firing temperature and additive ratios on physicomechanical properties

Abstract Clay bricks are widely used in construction due to their sustainability and cost-effectiveness. However, challenges such as high density and thermal conductivity hinder their broader application in energy-efficient buildings. This study investigates the effects of an expansion additive and varying firing temperatures (1000–1150 °C) on the physicomechanical properties of lightweight clay bricks. Six sample groups were prepared, incorporating expansion additive ratios from 0 to 4%. Key properties, including unit volume weight, water absorption, porosity, compressive strength, and thermal conductivity, were evaluated. Results identified the optimal conditions as 3.5% expansion additive and a firing temperature of 1150 °C, yielding a unit weight of 712 kg/m³, thermal conductivity of 0.1795 W/mK, and compressive strength of 7.05 MPa. These findings demonstrate the potential of chemically modified lightweight bricks for sustainable, energy-efficient construction.