Crumb rubber in concrete: Static and dynamic evaluation

In this study, six different concrete mix designs containing various amounts of coarse and fine crumb rubber were tested for properties important to concrete safety barriers. Eighteen samples – three of each mix design – were tested under static compression to determine the compressive strength and elastic modulus values. Another eighteen samples were subjected to dynamic drop tests to assess the effect of rubber on energy dissipation. Test results show that increasing the amount of rubber decreases the compressive strength and elastic modulus of the concrete, while significantly increasing impact time and energy dissipation capacity. It was determined that replacing 20–40% of aggregates with crumb rubber creates concrete mixes that would be useful for concrete safety barriers in locations where strength, fracture resistance and energy dissipation are required. Finally, concrete mixes with greater than 60% of aggregates replaced by crumb rubber would be useful for concrete impact attenuators in locations where low impact severity is of ultimate importance, and fracture or fragmentation upon impact is acceptable.

► Compressive strength decreases with an increase in the amount of rubber in concrete.
► The maximum impact load decreases as the amount of rubber increases.
► Rubber increases concrete’s impact resistance and energy dissipation capacity.
► Ability to absorb energy greatly reduces vehicle occupant injury risk during an accident.
► Flexible concrete incorporating rubber aggregate can be used as highway barriers.