The influence of polypropylene fibers on the properties of mortar

The influence of polypropylene fibers on mortar properties:

1. Polypropylene fibers play a role in transmitting stress inside mortar, bearing internal stress caused by substrate shrinkage. The average spacing between fibers in mortar is small, and there are more fibers per unit volume of mortar. The bonding area between fibers and cement matrix is large, and the interfacial bonding force between fibers and cement matrix increases the mortar's ability to resist shrinkage, deformation, and cracking.

2. Due to the addition of polypropylene fibers, the water retention performance of the mortar is improved, reducing the evaporation of moisture on the surface of the specimen; Polypropylene fibers, due to their small diameter and moderate length, are evenly dispersed after mixing, forming a three-dimensional random distribution in the mortar specimen. The fibers are in a bent state, increasing the bonding strength between the fibers and the mortar, suppressing the sinking of particles in the mortar, thereby reducing the capillary channels formed by water overflow in the mortar, delaying the occurrence of cracks, and controlling the development of cracks.

3. During the hardening process of mortar, due to the chemical shrinkage of cement slurry, tensile stress is generated at the bonding surface between cement slurry and aggregate. This is because there are a large number of extremely small microcracks in the mortar, which are prone to stress concentration and damage when the mortar is subjected to stress. Polypropylene fibers can effectively reduce the early shrinkage of mortar, that is, reduce the tensile stress at the bonding surface, thereby reducing the possibility of early failure of mortar.