不同环境对水泥混凝土早龄期水分蒸发效应的影响

The influence of different environment on water evaporation effect of cement concrete at early age

混凝土早龄期水分蒸发是微裂纹萌生的内动力,受温度、湿度(日照)、风速等因素影响,通过试验讨论环境风速、相对湿度、表层温度(日照)对混凝土水分蒸发速率影响的差异。结果表明:单一条件下,风速小于5 m/s时,温度对混凝土表面水分蒸发速率影响最大,风速影响次之,相对湿度影响最小;当风速大于5 m/s时,风速影响占主导,温度影响次之。环境风速、温度和相对湿度对混凝土表面水分蒸发速率峰值均出现在8 h以内,且风速和相对湿度存在一个明显的增强梯度值,其中风速梯度为大于9 m/s(极端天气才存在)、相对湿度梯度为小于50%(青藏高原常见),因此,青藏高原地区应关注浇筑后12 h内的保湿养护。

The evaporation of water in the early age of concrete is the internal driving force for the initiation of micro-cracks,which is affected by factors such as temperature,humidity(sunshine),and wind speed. In this paper,the effects of ambient wind speed,relative humidity,and surface temperature(sunshine) on the evaporation rate of concrete are discussed through experiments. The results show that when wind spead is less than 5 m/s,temperature has the greatest influence on the evaporation rate of concrete surface under a single condition,followed by wind speed,relative humidity. When the wind speed is greater than 5 m/s,the effect of wind speed is dominant,followed by temperature. The peak value of water evaporation on the concrete surface by ambient wind speed,temperature and relative humidity all appears within 8 hours,and there is an obvious enhanced gradient value of wind speed and relative humidity,in which the wind speed gradient is greater than 9 m/s(existing only in extreme weather). The relative humidity gradient is less than 50%(common on the Qinghai-Tibet Plateau). Therefore,the Qinghai-Tibet Plateau should pay attention to moisturizing and maintenance within 12 hours after pouring.