温湿度耦合效应下早龄期混凝土的相对湿度场

早龄期混凝土温度和相对湿度的时间空间变化规律是揭示混凝土早期开裂的关键。为此,建立了早龄期混凝土温度湿度耦合作用分析模型,采用无条件稳定向后差分格式,考虑水化作用、自干燥作用、温湿度扩散作用以及温湿度耦合机制,分析早期混凝土相对湿度的时间空间变化规律,定量揭示相对湿度的空间不均匀性,分析了水灰比、环境相对湿度以及表面水分交换系数等对相对湿度及其空间变化规律的影响。与实验结果的对比验证了模型的合理性,结果表明:温湿度扩散作用对相对湿度的影响随距扩散表面距离的增加而减小,水灰比对相对湿度的影响与位置无关,而环境相对湿度和表面水分交换系数主要影响混凝土扩散表面附近的相对湿度场。

Relative humidity analysis of early-aged concrete based on temperature and humidity interaction

The temporal and spatial variation characteristic of the temperature and relative humidity of early-aged concrete are dominant for the shrinkage cracking of early-aged concrete. The temperature and relative humidity interaction analysis model of early-aged concrete is present by the application of unconditional stable backward finite differential method. In the proposed model, the coupling effects of hydration, chemical drying and the diffusion of temperature and relative humidity are taken into account. The temporal and spatial variation of the relative humidity of early-aged concrete are simulated. The rationality of the proposed model is verified by the comparison with the test results. The parameters analysis have shown that the influence of temperature and humidity diffusion on relative humidity decreases with the distance from the diffusion surface. The influence of water-cement ratio on relative humidity is independent of position. The environmental humidity and surface moisture exchange coefficients primarily affect the relative humidity field near the concrete diffusion surface.