Mechanical Properties of Fiber-Reinforced Self-Compacting Geopolymer Concrete Using Lightweight Aggregate under Microwave Curing Condition

Geopolymer composites are remarkable binding materials due to their sustainability and recyclability. This study investigates the behaviour of Self-Compacting Geopolymer Concrete (SCGC) as a viable alternative to conventional concrete. It examines the effects of adding Lightweight Coarse Aggregate (LWCA) and Steel Fibre (SF) under different curing environments on the fresh and hardened properties of SCGC. Curing was applied using microwave and ambient environments. SF was added at 0%, 0.5%, 1%, and 1.5% of the binder content. Natural coarse aggregate was partially replaced with LWCA by weight at 0%, 33.3%, 66.67%, and 100%. The SCGC mixes were analysed in both fresh and hardened states to evaluate their mechanical properties. Results showed that higher LWCA and SF ratios led to more viscous and cohesive mixes. SCGC specimens under ambient curing exhibited lower compressive, flexural, and tensile strengths compared to those under microwave curing. Microwave-cured samples demonstrated improved performance, with a 38.09% increase in compressive strength for the B6 mix and a 28.02% enhancement in flexural strength. The highest tensile strength (TS) was 4.67 MPa for the B3 mix with 1.5% SF. However, using 66.67% LWCA under microwave curing resulted in a 27.9% reduction in TS. The study recommends using industrial-scale microwave curing and recycled materials, such as steel fibres and LWCA, to produce cost-effective and sustainable SCGC.