论文部分内容阅读
混凝土的质扩散系数(Dm)是混凝土材料的一种湿物性,它反映混凝土内部的湿份在空间上趋于均匀的能力。在混凝土温度保持不变的条件下,混凝土质扩散系数取决于材料的微观孔隙结构、初始含湿量的大小及其在空间上分布的均匀性。对同一种混凝土材料而言,混凝土质扩散系数强烈地依赖于混凝土内部的初始含湿率。本文首先从湿度扩散矩的概念上论证了混凝土的质扩散系数与其平均值(Dm)的关系;接着研究平均质扩散系数代替质扩散系数以后,混凝土湿度场的变化趋势;最后讨论了两种不同质扩散系数下混凝土干缩速度、干缩应变、非均匀干缩引起的约束应力等。以北方地区拆模后的大体积混凝土为例,计算了混凝土表面最大干燥应力与干燥深度,其成果可以为混凝土表面保护设计提供参考。
The mass diffusion coefficient (Dm) of concrete is a kind of wet physical property of concrete material, which reflects the ability of the internal moisture content of concrete to become more uniform in space. Under the condition of constant temperature of concrete, the diffusion coefficient of concrete depends on the microscopic pore structure, the initial moisture content and the uniformity of its distribution in space. For the same kind of concrete, the diffusion coefficient of concrete strongly depends on the initial moisture content of concrete. In this paper, the relationship between the mass diffusion coefficient and the average value (Dm) of concrete is first demonstrated from the concept of humidity diffusion moment. Then the variation trend of concrete humidity field after the average mass diffusion coefficient is replaced by the mass diffusion coefficient is discussed. Finally, two different Concrete diffusion rate under dry shrinkage rate, shrinkage strain, non-uniform shrinkage caused by restraint stress. Taking the large-volume concrete demolished in northern area as an example, the maximum dry stress and the drying depth of concrete surface are calculated. The results can provide references for the design of concrete surface protection.