Microstructural damage and durability of plateau concrete: Insights into freeze-thaw resistance and improvement strategies

Extreme environmental conditions and inferior building materials in plateau regions present significant challenges to the durability of concrete structures, particularly in resisting freeze-thaw cycles. This study employs an actual mix ratio from a concrete mixing station in the Qinghai-Tibet Plateau for a comparative analysis against conventional mixes in plain terrains. Utilizing a fast-freezing test with controlled variables, the study explores the microstructural evolution of plateau concrete. Results reveal that although the adapted mix ratio meets strength criteria, it falls short in frost resistance compared to standard concrete used in plain regions. Further, the plateauspecific curing conditions were shown to increase both the width and porosity of the interface transition zone (ITZ). High clay content in building materials for plateau construction also impacts the cement paste's microstructure. The study offers engineering recommendations aimed at enhancing the quality and performance of concrete in plateau conditions to address the unique challenges posed by extreme environmental factors.