Optimizing engineering potential in sustainable structural concrete brick utilizing pond ash and unwashed recycled glass sand integration

The Australian construction sector faces a dual challenge of high demand for concrete bricks and the need for sustainable materials. This research investigates eco-friendly structural concrete brick formulations, incorporating pond ash and unwashed recycled glass sand. It aims to provide scientific evidence on their engineering performance as per AS/NZS 4455.1:2008 standard, thermal insulation, and fire resistance properties. Additionally, microstructural, chemical, and pore-structure analyses are carried out to gain insights into the reaction mechanisms and the evolution of their properties. Findings indicate that bricks with 15 % pond ash and 20 % unwashed glass sand meet structural requirements with compression strength of 29.63 MPa at 28 days. Enhanced thermal insulation is observed due to the lower densities of pond ash and glass sand. After a 2-hour exposure to elevated temperatures, the unexposed surface of these bricks remains below 180°C, satisfying fire resistance criteria for wall elements. However, microstructure and chemistry analyses suggest lower compression and tensile strength comparable conventional bricks because of low reactivity of the pond ash and the smooth surface of the glass sand.