盐冻循环下混凝土结构的寿命预测

Life prediction of concrete structures under salt-freeze cycle

针对西北寒旱地区混凝土结构在服役过程中由于遭受温差、盐离子等因素的影响导致耐久性降低的问题,选取与研究对象具有相似服役环境和年限的参照建筑物,并构建具有相似配合比的混凝土试件进行室内快速冻融试验。建立室内外试验耐久性指标的衰减模型并对其衰变常数进行修正,进而完成对实际服役环境中混凝土结构寿命的评估和预测。结果表明:服役环境中渡槽近地面位置的损伤程度较大,危险系数更高,且排架对于槽身所遭受损伤较为严重,可直接制约渡槽整体使用寿命;盐冻循环中水灰比对混凝土影响较大,适量范围内水灰比越小混凝土的抗冻耐久性越好;通过试验数据进行拟合后发现二次多项式拟合的R2精度值较高,可以将混凝土的冻融损伤程度更为精确的表达出来。

In view of the durability reduction of concrete structures in cold and dry areas of Northwest China due to the impact of temperature difference,salt ions and other factors during service.The reference buildings with similar service environment and service life as the research object were selected and concrete specimens with similar mix ratio were constructed for indoor rapid freezing-thawing test.The decay model of indoor and outdoor test durability index was established and its decay constant was modified,and then the life of concrete structure in actual service environment was evaluated and predicted.The results show that in service environment,the damage degree of aqueduct near the ground is greater,the risk coefficient is higher,and the rack suffers more serious damage to the tank body,which can directly restrict the overall service life of aqueduct.In the salt-freeze cycle,the water-cement ratio has a great influence on concrete,and the smaller the water-cement ratio in the appropriate range,the better the freezing-resistance durability of concrete.After fitting the test data,it is found that the R2 precision value of quadratic polynomial fitting is higher,which can express the freeze-thaw damage degree of concrete more accurately.