Effect of fibers on chloride transport in mortars under unsaturated and saturated conditions

The effect of 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 was investigated using a natural immersion method. Moreover, the micromorphology of the fiber-mortar interface and the pore structure of fiber reinforced mortars were detected using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP), respectively. The results show that both of the steel fibers and polypropylene fibers have an insignificant effect on the chloride diffusion coefficient of mortars, no matter under unsaturated or 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.