Impact of crumb rubber and pre-treatment on the energy absorption of geopolymer concrete
Mohamed Aown, Safat Al‐Deen, Damith Mohotti
Abstract
This study investigates the energy absorption behaviour of Geopolymer Crumb Rubber Concrete (GCRC), a sustainable alternative to conventional concrete that replaces fine aggregates with crumb rubber derived from waste tyres and eliminates Portland cement through the use of alkali-activated binders. The research focuses on the effects of incorporating 25 % crumb rubber, with and without sodium hydroxide (NaOH) pre-treatment, on the static and dynamic performance of GCRC under localised concentrated loading. A total of 138 cube specimens (100 mm) were tested using a semi-spherical striker in both quasi-static and drop-weight impact regimes across a mid-range energy spectrum (75–105 J). This testing configuration, designed to simulate localised impact scenarios, offers a novel approach not previously applied to GCRC. Results show that untreated crumb rubber significantly increases normalised dynamic energy absorption by 41–59 % relative to control mixes, primarily due to the reduction in compressive strength. NaOH pre-treatment improves matrix bonding and restores peak impact force, but results in a 15–25 % reduction in normalised energy absorption due to increased stiffness and reduced ductility. A comparative analysis of mixes with similar compressive strengths confirms that strength, rather than rubber content alone, governs energy absorption per unit of strength. The experimental data generated in this study also provide a valuable reference for calibrating existing material models or validating new ones, enabling more accurate numerical simulations of GCRC under impact loading. These results serve as a foundation for future structural-scale testing, modelling, and design of impact-prone infrastructure components.