干湿交替下混凝土内部相对湿度变化规律  

Experimental Study on the Internal Relative Humidity in Concrete under Dry-Wet Cycles

作　　者：高原[1,2] 张君[1,2] 韩宇栋[1,2] 

机构地区：[1]清华大学土木工程系,北京100084 [2]清华大学土木工程安全与耐久教育部重点实验室,北京100084

出　　处：《建筑材料学报》2013年第3期375-381,共7页Journal of Building Materials

基　　金：国家自然科学基金资助项目(51178248);国家重点基础研究发展计划(973计划)项目(2009CB623200)

摘　　要：分别采用清水和硫酸盐溶液作为湿润溶液,对C30和C80这2个强度等级混凝土进行了干湿交替试验,测量了干湿交替下混凝土不同深度处的相对湿度随时间的发展规律.结果表明:在覆膜养护阶段,混凝土内部相对湿度的发展遵循两阶段发展模式,即首先经历一段湿度饱和期(湿度为100%),然后进入湿度下降期;混凝土内部相对湿度沿高度呈现明显的梯度;当混凝土进入干湿交替过程后,只有距混凝土表层一定深度范围内的相对湿度发生变化,大于此深度处的混凝土相对湿度基本保持不变,此深度即为干湿交替影响深度;不同强度等级混凝土在相同干湿交替条件下影响深度不同,混凝土水灰比越小,强度等级越高,影响深度越小;湿润过程采用硫酸盐溶液时,混凝土的干湿交替影响深度要比采用清水时大.Using clean water and sulfate solution as the wetting medium, the internal relative humidity in concrete under dry-wet cycles was measured. The test results show that at the beginning of concrete placement, the variation law of the internal relative humidity in concrete with age can be described by a watervapor saturated stage with 100% relative humidity followed by a stage that relative humidity gradually decreases and significant humidity gradient along the height can be found. Under dry-wet cycles, the changes of the relative humidity occur just within a certain depth from the concrete surface. This depth is common- ly known as the influencing depth. Under the same dry-wet cycles, different influencing depths were ob- served for concretes with different strength. The lower the water to cement ratio and/or the higher the concrete strength, the shorter the influencing depth. The influencing depth is larger when sulfate solution is used as the wetting medium than that when the clean water is used.

关 键 词：混凝土 干湿循环 内部相对湿度 

分 类 号：TU528.01[建筑科学—建筑技术科学]