Effect of ultra-low temperature freezing-thawing cycles on bending fatigue properties of PE-ECC

As human progress forges ahead in the domain of ultra-low temperature advancements, conventional concrete materials have been inadequate in addressing the exigencies of practical engineering demands, Engineered Cementitious Composites (ECC), an emerging class of novel composite materials, whose investigation concerning performance under ultra-low temperature environments assumes profound significance. This paper employed Polyethylene (PE) fibers to fabricate Engineered Cementitious Composites (ECC) and investigated the impact of varying ultra-low temperature freezing-thawing cycles lower limit temperatures, as well as the number of freezing-thawing cycles, on the bending static load strength and bending fatigue properties of PE-ECC specimens. The results show that changes in lower limit temperatures and the number of freezing-thawing cycles have a substantial effect on the flexural static load strength of PE-ECC, the flexural strength and bending deflection of the specimens exhibit a notable decrease in values. Across various freezing-thawing conditions, the toughness value is consistently lower than that of the control group unaffected by freezing-thawing, thereby indicating a compromised energy absorption capacity of the matrix. The strength of the interfacial bonding between the fibers and the matrix is reduced, leading to a conspicuous increase in fiber pullout damage when the specimen fails. The fatigue life of PE-ECC subjected to freezing-thawing in ultra-low temperatures follows the two-parameter Weibull distribution, the fatigue life equations of PE-ECC under different freezing-thawing conditions with different probabilities of reliability are obtained by regression analysis. The results of this study can serve as a reference for analyzing the fatigue life of PE-ECC at ultra-low temperatures freezing-thawing cycles.