复合盐与干湿循环双重因素作用下混凝土耐久性试验

吉林省大安市是松嫩平原土壤盐渍化最严重的地区之一，以苏打盐渍土为主，境内的土壤与地表水中的易溶盐分量相似。为了研究复合盐与干湿交替环境下混凝土的耐久性，根据大安地区盐渍土中主要易溶盐的含量，配制了4种不同质量分数的复合盐侵蚀溶液，再以水溶液用于试验对比，共制备了5种配合比的混凝土，进行盐浸-热烘试验。结果表明：在干湿循环条件下，复合盐对混凝土材料有较强的腐蚀性，而且盐溶液的质量分数越大，混凝土破坏越严重；干湿循环作用后，混凝土的质量变化规律为先增加后减少，而动弹性模量先呈小幅增长，达到一定干湿循环次数后，呈下降趋势；引气剂与粉煤灰均能够提高混凝土抗盐蚀-干湿循环的破坏能力，但引气混凝土提高效果更显著。

Experiment of the Concrete Performance the Condition of Multiple Salts and Dry-Wet Cycles

Da’an City, in the west of Jilin Province, is one of the most severe regions that suffer soil salinization in Songnen Plain. Saline-sodic soil is the main type in this area, and the composition of soluble salts in the soil is similar to that in the environmental water. In order to study the concrete durability under such an exposure condition, experimental work on the effect of the multi-salt and dry-wet cycles on concrete performance was carried out. Water and four solutions of different concentration of multi-salt were prepared and used to simulate the concentration and the main types of the dissolved salts in the saline soil in Da’an region. The durability property of the concrete with five different mix proportions was evaluated through the tests of multi-salt and dry-wet cycles. The experimental results indicated that multi-salt had corrosive action on concrete under the condition of dry-wet cycles, and the higher the concentration of the multi-salt solution, the more severely the concrete was degraded. With the increasing times of dry-wet cycles, the mass of concrete and the dynamic elastic modulus of concrete showed a slight increasing at first, and then reduced after a certain number of dry-wet cycles. Air-entrained concrete and fly ash concrete were found have better behavior under such exposure condition, and much better improvement could be observed in the air-entrained concrete.