Experimental and numerical study of steel fibre reinforced geopolymer concrete slab under impact loading

Geopolymer concrete (GPC) is a promising, environmentally friendly alternative to ordinary Portland cement concrete (OPC), but its brittleness remains a challenge. This study investigates the behaviour of steel fibre reinforced geopolymer concrete (FR-GPC) slabs under both static and impact loading, using hooked-end steel fibres at a 0.5 % volume fraction. Impact test was performed using a 565 kg pendulum at varying impact velocities between 2.5 m/s and 4.9 m/s. The static and impact performances of FR-GPC slabs in comparison to plain GPC slabs were evalauted. The results reveal that under both static and dynamic loading conditions, FR-GPC slabs demonstrate enhanced punching shear resistance, energy absorption, and impact resistance. The addition of steel fibres alters the failure mode from pure punching shear to combined shear and flexural failure. A detailed numerical model, validated against experimental results, is developed to predict the dynamic behaviour of FR-GPC slabs. Subsequent parametric studies are conducted to assess various factors on impact resistance, where the enhanced performance of FR-GPC slabs in impact resistance and energy absorption is primarily influenced by the slab thickness and concrete strength, while the reinforcement ratio has a lesser effect. Based on these studies, empirical formulas are proposed to estimate the dynamic punching resistance of reinforced FR-GPC slabs.