Degradation of properties of panel concrete under the coupled environment of freeze–thaw and carbonation Available to Purchase

Panel concrete structures of concrete-faced rockfill dams (CFRDs) in China’s Three-North regions are frequently exposed to freeze–thaw (FT) cycles and carbonation, which pose significant durability challenges. In this study, the durability performance of panel concrete under the coupled effects of FT and accelerated carbonation (AC) was investigated. The mass loss, relative dynamic modulus of elasticity, splitting tensile strength and carbonation depth were evaluated under individual and combined environmental conditions. The degradation behaviour of the panel concrete was systematically analysed. The results showed that the loss of dynamic modulus under coupled action exceeded that observed under individual exposure, regardless of whether AC preceded FT cycles or whether FT preceded AC. The interactive deterioration mechanism between FT and AC was further explored through scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. The results revealed that FT cycles led to the propagation of microcracks and accelerate the penetration of carbon dioxide and carbonation reactions. Although carbonation increased the compactness of the concrete, the volume shrinkage of reaction products caused internal stress and cracking, and the long-term coupling effect of FT and AC two will accelerate damage. A damage prediction model for panel concrete subjected to the coupled effects of FT and AC was subsequently established. The remaining life of panel concrete in different climatic zones of China was estimated, offering critical scientific support for the durability design of CFRD engineering.