Corrosion resistance of multiscale polypropylene fiber-reinforced concrete under sulfate attack

To study the corrosion resistance properties of multiscale polypropylene fiber-reinforced concrete (MPFRC) when subjected to sulfate attack, two types of fine polypropylene fiber (FPF) and one type of coarse polypropylene fiber (CPF) were selected for single doping or hybridization into concrete. A sodium sulfate solution (10 wt%) was used in the sulfate attack drying-wetting cycle. A one-dimensional SO42- concentration distribution model was established. The corrosion resistance mechanism of polypropylene fiber-reinforced concrete (PFRC) was revealed based on concrete compressive strength tests, ion concentration tests, and micro tests under different sulfate attack ages. The results showed that PFRC maintained its integrity even after being subjected to sulfate attack. After 20 drying-wetting cycles, the MPFRC exhibited the highest compressive strength; the SO42- concentration of the double-doped polypropylene fiber-reinforced concrete and MPFRC at 18 mm depth were 9.07% and 9.52% lower than those of the plain concrete and single-doped polypropylene fiber-reinforced concrete, respectively. The SO42- concentration distribution model could well describe the SO42- concentration distribution characteristics of the PFRC under one-dimensional sulfate attack. The diffusion coefficients (D) of the double-doped polypropylene fiber-reinforced concrete and MPFRC were 30.0% and 47.7% lower than that of plain concrete, respectively. Thus, among the concrete specimens used in this study, the MPFRC showed the best performance in terms of corrosion resistance.