Zones of weakness of rubberized concrete behavior using the UPV

•Crumb rubber from recycled tires was used in partial replacement of sand in concrete.•Rubberized concrete performance under compression load.•Optimal content of crumb rubber in concrete mix.

Many studies have addressed the recycling of rubber tires as a replacement material for fine or coarse aggregates used in concrete mixes. This research has focused on detecting the optimal amount of crumb tires as a partial substitute for fine aggregates in concrete mixes without radically affecting its main properties. Moreover, the performance of rubberized concrete with crumb rubber partially substituted for fine aggregates in various percentages (from 0% up to 100%) by volume has been studied under axial compression. The nondestructive, Ultrasonic Pulse Velocity (UPV) testing method has been implemented for this purpose. This approach has not been used for this purpose in the literature so far. The test results indicated three zones of weaknesses in rubberized concrete. However, Zone A demonstrated that even though the compressive strength is reduced it remains within accepted limits. Therefore the optimal rubber percentage was found to be 25% which is the boundary of zone A.