Abstract: Freezing-thawing environment will cause freezing damage to hydraulic concrete, including skin peeling, cracking, and loosening, detrimental to the durability of hydraulic concrete in cold regions. The frost resistance of hydraulic concrete can be improved by adding materials to enhance the internal pore structure. We made a review on the influences of concrete structure, construction conditions and external environment on the freezing damage of hydraulic concrete in cold regions, and summarized the changes in strength, quality and elastic modulus of fiber concrete, nano-concrete and air-entrained concrete after freezing and thawing. Furthermore, we expounded the mechanism of enhancing the frost resistance of hydraulic concrete by adding materials, and put forward the research prospect in technologies enhancing the performance of hydraulic concrete in cold regions. Such researches should include: the failure characteristics and reinforcement technology of hydraulic concrete under multiple freeze-thaw cycles at ultra-low temperature with large temperature difference; the coupling effect of freeze-thaw, salt erosion and load on frost resistance of hydraulic concrete; a set of comprehensive evaluation system to objectively reflect the strengthening effect of external materials on concrete; the advantages of enhancement technologies, the economy, environmental protection, durability and other objective factors; verification and optimization of demonstration projects, and practical engineering application of reinforcement technologies of hydraulic concrete in cold regions.

Key words: hydraulic concrete, freezing damage, freezing resistance, reinforcement mechanism, research progress