Effect of polymer fibers recycled from waste tires on properties of wet-sprayed concrete

This study explores the possibility of using recycled tire polymer fibers (RTPF) as a micro-reinforcement in wet-sprayed concrete mixes. Two groups of mixes were made: sprayed concrete mixes with and without an air-entraining admixture. Each group comprised mixes with 0.9 and 1.8 kg/m 3 of RTPF. To facilitate comparison, the groups contained either a plain mix, without fibers, or a mix with polypropylene (PP) fibers, usually used to control early-age cracking. The mixes were tested for their transport properties, including capillary absorption and gas permeability, freeze–thaw resistance, and autogenous and restrained deformation. Results show the beneficial effect of RTPF during freeze–thaw cycles and the deformation resistance of wet-sprayed mixes. Observed differences in the transport properties between mixes with and without air entrainment are explained by changes in pore structure, tested using mercury intrusion porosimetry (MIP).