混凝土干湿过程及循环制度的研究

Investigation of the Process and Regime of Drying and Wetting of Concrete

关键词:  干湿循环制度  干燥和湿润过程  蒸发/吸水量  相对湿度

Key words:  drying wetting cycle regime  drying and wetting process  mass of water evaporation/absorption  relative humidity

摘要:

将混凝土的干湿循环过程分解为干燥和湿润过程，对其干湿过程中不同深度相对湿度的变化规律、水量蒸发/吸收规律及氯离子对水分传输的影响进行了研究.结果表明：测定混凝土干湿过程中的蒸发/吸水量、相对湿度，可合理制定干湿循环制度，并进行室内试验与现场环境的加速倍率换算；在干湿初期，混凝土失水/吸水速率最大，之后大幅减小；干燥时间决定了混凝土的劣化深度，制定干湿循环制度时宜延长干燥时间，缩短润湿时间；离子的存在不影响混凝土水分的传输方式，但会大大降低其毛细吸附和扩散传输效果.

Abstract:

Process of the drying and the wetting for concrete were investigated separately. The change of relative humidity(RH) in different depths of concrete with time during the drying and the wetting was monitored. The mass of average evaporation/absorption of water during the drying and the wetting process was also measured, and then the influence of chloride ion on water transportation was considered. The test results show that the drying and wetting regime of concrete can be rationally determined according to the RH and the water evaporation/absorption during the drying and wetting process. The RH and the water evaporation/absorption obtained in the lab can be transferred to assess the effect of drying and wetting on the in site concrete. The evaporation/absorption rate is the highest during the early drying and the wetting process, and subsequently slows down. The degraded depth of concrete is determined by the drying process, therefore the drying time shall be long while the wetting time be short. Water transportation mode shall not be influenced by the chloride ion, while the capillary absorption coefficient and diffusion coefficient of concrete markedly decreases.