Effects of recycled tyre rubber and steel fibre on the impact resistance of slag-based self-compacting alkali-activated concrete

Accumulation of waste tyres causes an environmental disaster because of the rapid rise in transport vehicle demand resulting from modern developments, Covid-19 and similar pandemics. Thus, recycling waste tyres in the form of aggregates as a sustainable construction material can be a solution to reduce the environmental problems. Current research focuses on the impact resistance and mechanical properties of the crumb rubber self-compacting alkali-activated concrete reinforced with 1% steel fibres (SFs) where fine and coarse crumb rubbers (CR) are partially replaced with 10% and 15% replacement ratios. The compressive, flexural, splitting tensile strengths and modulus of elasticity were investigated; impact resistance was found using a drop hammer impact test. The incorporation of CR reduced the mechanical properties, and the reduction was found more with increased rubber contents, whereas the incorporation of SF compensated for the strength loss. The impact performance was enhanced with the CR and SF incorporations. The 15% CR incorporation improved the impact energy up to three times, whereas both 1% SF and 15% CR incorporations significantly enhanced the impact energy up to 30 times. Similar mechanical strengths were obtained for the different sizes of CR. However, impact performance was significantly influenced by the sizes of CR.