Predicting the flexural behavior of steel-PVA hybrid fiber reinforced cementitious composite

Abstract

In this paper, experimental and theoretical investigations were performed on the flexural response of steel-PVA hybrid fiber reinforced cementitious composite (SPHFRCC). For the experimental part, a series of slump flow tests, direct tensile tests, and four-point bending tests were performed to explore the effect of the sand/binder ratio (S/B) (1.08, 1.18, 1.28), fiber content (0, 1.5%, 1.6%, 1.75%, 1.9%), and fiber hybrid proportion (1:15, 1:6, 4:15, 2:5, 3:4). The main findings manifested that increasing PVA fiber content can seriously weaken the workability of SPHFRCC, while the impact of S/B was negligible. Maintaining a steel fiber content of 1.5% and adding PVA fiber from 0 to 0.4% resulted in a decrease in the slump by 12.3% and slump flow diameter by 43.0%. The post-cracking tensile response of SPHFRCC demonstrated strain hardening due to the presence of PVA fibers. Moreover, increasing PVA fiber proportion can tremendously raise the flexural strength and toughness, while the enhancement at an excessively high proportion of PVA fibers would be weakened. With a total fiber content of 1.75%, the addition of PVA fibers at 0.25%, 0.5%, and 0.75% to partially replace steel fibers resulted in an increase in the flexural strength by 9.3%, 34.3%, and 22.4%, and the flexural toughness corresponding to the deflection L/150 by 43.8%, 42.2%, and 47.2%, respectively. In the theoretical part, a novel tensile constitutive model was developed considering the probabilistic model and the effect of fiber pullout orientation. Also, a calculation method for the flexural response of SPHFRCC beams was presented in accordance with the sectional analysis. The validity of the developed models was evaluated by the comparisons between the test values and estimated curves.