海洋环境下混凝土相对湿度响应

Relative humidity response of concrete under marine environment

混凝土放置于青岛室内大气环境、海洋大气区、浪溅区环境以及模拟干燥的恒温恒湿、45°C烘干环境,模拟湿润的毛细吸水环境,测试混凝土深度为10-40 mm的相对湿度演变。研究结果表明：饱和混凝土相对湿度受环境湿度影响先稳定、再快速下降然后缓慢下降,包括水气饱和期和相对湿度减小期。混凝土内部相对湿度对环境湿度响应时间上存在滞后性,离表层越近响应速度越快,环境湿度越小,影响深度越大。室内大气环境、海洋大气区、海洋浪溅区、恒温恒湿及烘干环境下养护42 d,混凝土10-20 mm深度的相对湿度分别为90%-92%,85%-90%,90%-95%,89%-92%和57%-58%。干燥过程中混凝土相对湿度与时间变化关系受水分向外扩散过程控制;混凝土表观湿度扩散系数随深度增加而线性增加,表面层平均相对湿度与深度的关系符合对数函数关系。在湿润过程中,表面层相对湿度演变可用毛细传输系数公式进行分析,内部相对湿度演变是传输与扩散共同作用所致。

Concretes were placed in marine environment including indoor atmospheric zone, marine atmospheric zone,splash zone, and placed in simulated marine tidal zone including drying environment and wetting environment. Then the inner relative humidity（RH） evolution of concrete under above-mentioned environments was systematically investigated.The results show that the inner RH evolution of concrete includes vapor phase saturation stage and relative humidity decrease stage. The RH of concrete keeps steady firstly, and then rapidly decreases with time, lastly slowly declines. The inner RH response of concrete lags behind the environment humidity and the RH response speed of surface zone are faster than those of interior zone. The smaller the environmental humidity, the bigger the influence depth. The RH of concrete in 10-20 mm depth, which occurred in indoor atmospheric zone, marine atmospheric zone, marine splash zone,constant temperature and humidity environment and in drying environment for 42 d, is 90%-92%, 85%-90%, 90%-95%,89%-92% and 57%-58%, respectively. The inner RH change of concrete under drying environment is controlled by water diffusion from the interior to exterior, and can be described by the revised diffusion flux law. The apparent humidity diffusion coefficient decreases with depth, and the relationship between mean relative humidity of surface zone and depth can be represented by logarithmic function. In the wetting environment, the RH evolution in surface zone of concrete can be analyzed by the water capillary transport function, but the interior RH change is due to the capillary absorption and diffusion mechanism.