Effect of partial replacement of sand by recycled fine crumb rubber on the performance of hybrid rubberized-normal concrete under impact load: experiment and simulation

In this study, the effect of partial replacement of sand by recycled fine crumb rubber on the performance of hybrid concrete (double layer beam with rubberized top and normal bottom) under impact three-point bending loading was investigated experimentally and numerically. Rubberized concrete mixes were prepared by partial substitution (10% and 20% replacements by volume) of sand by recycled fine crumb rubber of particle size 0.16–2.36 mm. Two types of specimens (size 50 mm × 100 mm × 400 mm) namely, plain concrete and hybrid concrete were loaded to failure in a drop-weight impact machine by dropping a 20 N weight from height 300 mm to the middle of a simply supported beam, and similar specimens were used for the static load test. The bending load–displacement behavior was analyzed for the normal and hybrid concrete beams, under static and impact loads. The dynamic beam behavior was also analyzed numerically using the finite-element method (FEM) based on LUSAS V.14 software. eral, the results reveal that the impact ultimate bending load that can be resisted by the hybrid beam increases with increase in the percentage of sand replacement by recycled fine crumb rubber, while the static peak bending load always decreases. The use of hybrid rubberized concrete beam improves flexural impact performance of the beam during dynamic loading compared to the static loading. Moreover the addition of rubber improved the toughness and deformation ability of the normal concrete.