@Article{sdhm.2026.083733,
AUTHOR = {Yongbing Sun, Dewen Liu, Qian Wang, Yuexia Yang, Canhuan Pan},
TITLE = {Investigation of Early-Age Freeze-Thaw-Induced Damage Evolution in UHPC and the Structural Strengthening Efficacy of CFRP Systems},
JOURNAL = {Structural Durability \& Health Monitoring},
VOLUME = {},
YEAR = {},
NUMBER = {},
PAGES = {{pages}},
URL = {http://www.techscience.com/sdhm/online/detail/27749},
ISSN = {1930-2991},
ABSTRACT = {During winter construction in cold regions, ultra-high performance concrete (UHPC) is susceptible to early-age freeze-thaw cycles caused by improper curing or sudden cold waves. This study investigates the damage evolution of UHPC under freeze-thaw cycles and the subsequent strengthening effect of carbon fiber reinforced polymer (CFRP). Early-age (7-day cured) UHPC specimens were subjected to coupled freeze-thaw and chloride salt (5% NaCl) exposure. Damage was characterized by ultrasonic wave velocity, compressive strength, and SEM-EDS analysis. Results show that as the number of freeze-thaw cycles increases, mass loss reaches 1.35% at 150 cycles, while wave velocity decreases by 1.14%. Control specimens (without freeze-thaw) exhibited a 24.6% increase in compressive strength with age (corresponding to 150 cycles), whereas the strength of specimens subjected to 150 cycles decreased by 19.9%. After CFRP strengthening, the ratio η (strength of strengthened specimens to that of unstrengthened control specimens of the same age) declines with increasing cycles. The ratio α (strength of strengthened damaged specimens to that of unstrengthened damaged specimens of the same age) reaches 113.1% at 150 cycles, a 3.60% decrease from its initial value, indicating that more severe freeze-thaw damage leads to lower reinforcement efficiency. Microscopic analysis reveals that after 150 cycles, the chloride ion content reaches 0.3 wt%, steel fibers corrode, and the number of pores and microcracks increases. Meanwhile, the Ca/Si atomic ratio decreases due to calcium ion leaching and secondary hydration of silica fume. This study elucidates the evolution mechanism of early-age freeze-thaw damage in UHPC and validates the effectiveness of CFRP strengthening, providing a practical basis for the protection and retrofitting of UHPC structures in cold regions.},
DOI = {10.32604/sdhm.2026.083733}
}