Research on freeze-thaw damage and life prediction model of polyethylene fiber-reinforced cementitious composites based on reliability analysis

Engineered Cementitious Composite (ECC), is a fiber-reinforced cementitious composite with excellent ductility, toughness, impact resistance and multi-crack development characteristics. In addition to the excellent mechanical properties, the durability of ECC has also received equal attention. In order to investigate the frost resistance of polyethylene fiber-reinforced cementitious composites (PE-ECC), PE-ECC and normal concrete (NC) specimens were subjected to different numbers of freeze-thaw cycles, and the changes in compressive strength, mass loss rate and relative dynamic modulus of elasticity of the specimens before and after freezing and thawing were tested, so as to compare the freeze-resistant properties of PE-ECC and NC. A freeze-thaw damage model was established using the two-parameter Weibull distribution function, and the freeze-thaw reliability of NC and PE-ECC was analyzed based on the Wiener process analysis, based on which a life prediction model was established to predict the life of NC and PE-ECC under freeze-thaw environment. The results show that after 200 freeze-thaw cycles, the compressive strength loss rate, mass loss rate and the relative dynamic elastic modulus loss rate of NC and PE-ECC are 32.97%, 2.35%, 50.28% and 17.28%, 0.71%, 6.57%, respectively, and the damage indexes of PE-ECC are lower than that of NC, and the NC after 200 freeze-thaw cycles has reached the standard of freeze-thaw damage, while PE-ECC is still at a lower level of freeze-thaw damage; it shows that the frost resistance of PE-ECC is better than that of NC, and the addition of PE fibers can effectively improve the frost resistance of concrete; the results of the damage model and the reliability analysis coincide well with the experimental results, and the results of life prediction are given in some cold regions, which can provide a basis for the application of PE-ECC in practice.