The Effect of Freeze-Thaw Cycles on the Basic Mechanical Properties of PVA-ECC Materials

Abstract

To investigate the frost resistance and mechanical performance stability of Polyvinyl Alcohol Engineered Cementitious Composites (PVA-ECC) in cold regions, a series of rapid freeze-thaw tests were conducted on PVA-ECC specimens with four fiber volume contents (0%, 1.0%, 1.5%, and 2.0%). The effects of freeze-thaw cycles (0, 50, 100, 150, and 200 cycles) on the surface morphology, mass loss rate, relative dynamic elastic modulus, and cubic compressive strength of the specimens were systematically analyzed. The results indicate that freeze-thaw cycles cause cumulative damage to PVA-ECC, manifested as aggravated surface mortar spalling, increased mass loss, decreased relative dynamic elastic modulus, and degraded compressive strength. However, the incorporation of PVA fibers significantly improves the material's frost resistance and mechanical stability through the bridging effect and structural optimization. With the increase in fiber volume content, the damage degree of PVA-ECC under freeze-thaw cycles is remarkably reduced. After 200 freeze-thaw cycles, the specimen with 2.0% fiber content maintains an intact overall structure, with a mass loss rate of only 2.76%, a relative dynamic elastic modulus retention rate of 73.19%, and a cubic compressive strength of 31.73 MPa (strength loss rate of 30.26%). In contrast, the fiber-free specimen fractures after 75 freeze-thaw cycles, with a mass loss rate of 9.49% and a strength loss rate of 50.05%. This study demonstrates that PVA fibers can effectively inhibit the initiation and propagation of microcracks induced by freeze-thaw cycles, enhance the bonding stability between the matrix and fibers, and reduce internal structural damage. The findings provide experimental data and technical support for the application and popularization of PVA-ECC in cold-region engineering.