Effects of hybrid fibers on workability, mechanical, and time-dependent properties of high strength fiber-reinforced self-consolidating concrete

Abstract

Abstract This paper aims to systematically investigate the impacts of hybrid fibers on properties of high strength fiber-reinforced self-consolidating concrete (FRSCC). In total, nine mixtures with different fiber types (Polyvinyl Alcohol/PVA, and hybrid fibers) and fiber factors (λ\xa0=\xa00\xa0~\xa070) were fabricated with same basic mix proportioning. Workability tests include slump flow, T50 time, and J-ring tests were carried out to quantify the effects of fiber factor. The compressive strength, four-point bending tests, drying shrinkage, and compressive creep tests were performed on hardened concrete to reveal the intrinsic effects of single/hybrid fibers. Finally, a hyperbolic drying shrinkage prediction model with fiber factor was proposed. Experiment results indicated that single PVA fibers displayed identical influences on slump flow as steel fiber with similar fiber factor, however, can result in higher viscosity. Meanwhile, PVA fibers reduced the compressive strength and displayed limited restraining effects on the specific creep. However, the positive synergetic effects of hybrid fibers can reverse the reductions in compressive strength caused by the PVA fiber and increase flexural performances with multi-scale bridge effects. Moreover, hybrid fibers are more effective in inhibiting the time-dependent strains of FRSCC, followed by steel fiber and synthetic PVA fiber. The proposed hyperbolic drying shrinkage model is capable of predicting the drying shrinkage of FRSCC with a suitable shrinkage halftime.