水工混凝土冰冻害机理及抗冻性能研究进展

Research Progress of Freezing Damage Mechanism and Frost Resistance of Hydraulic Concrete

冻融环境作用下水工混凝土会发生冰冻害破坏,出现表皮脱落、开裂和松动等现象,显著影响寒区水工混凝土的耐久性。外加材料可增强内部孔隙结构,从而提高水工混凝土的抗冻性。综述了混凝土自身结构、施工条件和外部环境等因素对寒区水工混凝土的冰冻害影响;总结纤维混凝土、纳米混凝土以及引气混凝土在冻融后的强度、质量以及弹性模量变化;进而阐述外加材料对水工混凝土抗冻性的影响机理。最后,提出寒区水工混凝土性能增强技术的研究构想:开展超低温-大温差以及多次冻融循环条件下水工混凝土破坏特性及增强技术研究;加强冻融、盐侵蚀及荷载耦合作用对水工混凝土抗冻性能的影响研究;提出一套完整的评价体系以客观地反映外加材料对混凝土的增强作用;综合考虑水工混凝土增强技术性能优势、经济环保、耐久性等客观因素,加强寒区水工混凝土增强技术示范工程验证与优化,扩大其实际工程应用。研究成果可为我国寒区水利工程中混凝土构筑物的建设及运营维护等提供重要技术支撑。

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.