Ordinary concrete has high brittleness and low fatigue resistance, which cracks easily under the action of internal and external factors, such as load, temperature and humidity changes, shrinkage, and so on. The addition of fibers to ordinary concrete can effectively improve the tensile strength, flexural strength and toughness. Specifically, the randomly distributed fibers in concrete limit the expansion and cracking of concrete and improve its crack resistance. The addition of fibers inevitably affects the transmission of external hazardous substances in concrete while improving its mechanical properties and crack resistance, however, it is insufficient and not matured in this area.



This study focused on the effect steel fibers (0-1.5% by volume) and polypropylene fibers (0-0.5% by volume) on chloride transport in mortars under unsaturated and saturated conditions. Moreover, the micromorphology of fiber-mortar interface and the pore structure of fiber reinforced mortars were detected using scanning electron microscope (SEM) and mercury intrusion porosimetry (MIP), respectively. The results show that both of the steel fibers and polypropylene fibers have insignificant effect on the chloride diffusion coefficient of mortars, no matter under unsaturated and saturated conditions. The incorporation of steel fibers has no obvious action on the pore structure of mortars, and the interfacial zone around the steel fibers is not a preferential path for chloride transport. However, the addition of 0.1-0.5% polypropylene fibers refines the pore size of mortars, and yet slightly increases the total porosity. The polypropylene fiber-mortar interface is insignificant, while the agglomerate of polypropylene fibers exists.