柴达木盆地冻融、盐蚀环境下混凝土腐蚀机理及耐久性研究

为研究柴达木盆地地区强腐蚀环境下混凝土结构的耐久性,配制与现场土壤腐蚀浓度相近的腐蚀性溶液,对掺加特定外加剂的不同强度等级混凝土试件进行冻融、盐浸循环试验,通过检测试件的电通量、强度损失率、质量损失率等参数研究其腐蚀规律及耐久性。试验结果表明,在强腐蚀环境下,低强度混凝土耐久性较差;掺加抗冻防腐剂后混凝土密实性可提高28%~53%,抗压强度损失率可减小22%~54%;氯盐对混凝土的侵蚀破坏起主导作用;混凝土腐蚀破坏前期表现为盐类结晶膨胀型破坏,后期主要是氯盐溶蚀破坏;混凝土破坏为氯盐和硫酸盐共同腐蚀的破坏效果叠加。根据试验结果及腐蚀机理,提出强腐蚀环境下考虑设计、施工、养护的混凝土结构耐久性综合设计方案。

Study on Corrosion Mechanism and Durability of Concrete Subjected to Freeze-thaw and Salt Erosion Qaidam Basin

In order to study the durability of the concrete structure in the strong corrosive environment in the Qaidam Basin,Prepare a corrosive solution that is similar to the on-site soil corrosion concentration,Perform freeze-thaw and salt immersion cycle tests on concrete samples with different strength levels mixed with additives,By testing the electrical flux,strength loss rate,mass loss rate and other parameters of the concrete specimen after the test,the corrosion law and durability of the concrete in this environment are studied.Through experiments,it is found that under strong corrosion environment,the durability of low-strength concrete is poor;after adding antifreeze antiseptic,the density of concrete can be increased by 28%~53%,the compressive strength loss rate can be reduced by 22%to 54%;the erosion of concrete by chloride salts in Qaidam area is dominant;the corrosion damage of concrete in the Qaidam area in the early stage showed salt crystal expansion damage,and the later period was mainly chloride salt corrosion damage;under the common corrosion of chloride and sulfate,the destruction effect of the two is superimposed;finally,according to the test results and the corrosion mechanism,a comprehensive design scheme for durability of concrete structures considering design,construction and maintenance in a strong corrosion environment is proposed.