Mechanical and Seismic Behaviour of Lightweight Geopolymer Concrete Using Expanded Perlite

The development of sustainable structural materials is critical for reducing the environmental impact of construction. This study investigates lightweight geopolymer concrete (LWGC) incorporating expanded perlite aggregate (EPA) at 0–20% replacement of fine aggregate. Fresh and hardened properties, including workability, density and compressive and flexural strengths, are evaluated experimentally, while the modulus of elasticity is determined empirically. Microstructural investigation is conducted to examine the interaction between EPA and the geopolymer matrix. Finite element analysis (FEA) is employed to evaluate structural response under seismic loading using experimentally derived material properties. The experimentally observed porosity and stiffness reduction due to lower modulus of elasticity, were reflected in the seismic response analysis, demonstrating enhanced damping capacity. Existing studies on LWGC with EPA primarily address density reduction and strength development, with limited consideration of seismic performance. The results indicate that increasing EPA content improves workability and reduces density while maintaining adequate mechanical properties.