Study on early-age cracking resistance of multi-scale polypropylene fiber reinforced concrete in restrained ring tests

Abstract

The primary cause of early-age cracking is high tensile stress resulting from restrained shrinkage of concrete structures. This study examined the shrinkage performance of polypropylene fiber reinforced concrete (PFRC) through restrained ring and free shrinkage tests. The impact of polypropylene fiber on shrinkage deformation and restrained shrinkage stress of concrete was analyzed. Furthermore, the mechanism of multi-scale polypropylene fiber to improve the crack resistance of PFRC was discussed. Test results demonstrated that adding polypropylene fiber to concrete significantly reduced the possibility of early cracking in concrete matrix. Plain concrete (A0) showed the highest potential for early-age cracking. At 28 days of age, the cracking risk factor of single-doped, double-doped, multi-doped polypropylene fiber reinforced concrete (A1, A2, and A3) was 0.851, 0.793, and 0.665, which decreased by 7.1%, 13.43%, and 27.4% compared with A0, respectively, suggesting the effect was better positive in reducing the crack risk when multi-scale polypropylene fiber hybridized.