盐渍土环境下混凝土的抗冻性研究

THE FREEZING RESISTANCE PERFORMANCE OF CONCRETE IN SALINE SOIL ENVIRONMENT

文中主要研究了盐渍土环境中复合盐溶液、氯化钠溶液、硫酸钠溶液和水中不同强度等级混凝土的抗冻耐久性,研究结果表明,对于含气量4%的C30混凝土在水中冻融时可到达F200,C40和C50强度等级的混凝土可达到F300次以上,其破坏以相对动弹性模量的降低为主要表现形式;C30、C40、C50混凝土在4%氯化钠溶液中分别在90、105和260次冻融循环后即发生了破坏,表现形式为表面剥蚀;混凝土在硫酸盐溶液中的冻融破坏表现为相对动弹性模量降低和剥落量增加同时发生,冻融破坏次数介于水和氯盐之间;混凝土在复合盐溶液中的破坏高于单一盐溶液,在冻融-干湿循环耦合作用下,混凝土的破坏更为迅速,在复合盐溶液中经历5次耦合循环作用即发生破坏。

This article mainly studies the freezing resistance of concrete of different strength grade in saline soil environment including compound salt solution,sodium chloride solution,sodium sulfate solution,and water.The results show that freeze-thaw cycling times can reach F200 levels in water for C30 concrete with 4%air content and more than F300 levels for C40 and C50,moreover,the main form of failure is the decrease of the relative dynamic elastic modulus.In addition,the freeze-thaw cycling times of concrete whose strength grade are C30,C40,C50 in 4%sodium chloride solution reaches 90,105 and 260 respectively with the surface scaling failure mode;The freeze-thaw damage of concrete in sulfate solution showed that the decrease of relative dynamic elastic modulus and the increase of scaled mass simultaneously,and the freeze-thaw cycling times are between water and chloride salt solution.Furthermore,the damage of concrete in the compound salt solution is stronger than that of a single salt solution;Under the coupling effect of freezing resistance and dry-wet cycles,the failure of concrete is within a rather short time,and the failure occurs after 5 times of coupling cycles in the compound salt solution.