基于细观力学方法的混凝土热膨胀系数预测

建立混凝土材料的有效性质与微结构参数之间的关系,是混凝土材料优化设计的基础。本文用细观力学方法对复合材料宏观有效热膨胀系数进行研究,得到了含有一球形夹杂物的无限大介质在均匀变温作用下的应力场。假定混凝土为由骨料和砂浆基质组成的二相复合材料,根据混凝土宏观体积热膨胀量与组成混凝土的各相介质细观体积热膨胀量相等的原则,采用基于Mori-Tanaka方法的混凝土宏观有效剪切模量,推导出混凝土有效热膨胀系数的解答。对稀疏解法、自洽方法和有限单元数值试验结果的比较说明,本文提出的基于自洽方法的混凝土宏观有效热膨胀系数的理论公式能够较好的描述混凝土的热学特性,该方法可以推广到多相复合材料宏观有效热膨胀系数的预测中。

Prediction on thermal expansion coefficient of concrete based on meso-mechanics method

Correlating the effective properties of concrete materials with their micro-structures is a basis for optimization of concrete materials.In this article,the stress field of infinite medium uniformly heated containing a spherical inclusion is obtained by use of the theorem of meso-mechanics to study the macroscopic effective coefficient of thermal expansion of concrete.Assume that the concrete is a two-phase composite composed of mortar and aggregate and that the quantity of the macroscopic volume expansion of concrete is equal to the total quantity of mesoscopic volume expansion of the two-phase medium of concrete.Using the macroscopic effective shear modulus of concrete based on method of Mori-Tanaka gives the solution of the macroscopic effective coefficient of thermal expansion of concrete.The comparison of the numerical results derived from dilute method,self-consistent method and finite element method,respectively,illustrates that the theoretical formula of macroscopic effective coefficient of thermal expansion of concrete based on the self-consistent method provided in this paper, can be applied to describe the thermodynamics behavior of concrete.This method can be used to predict the macroscopic effective coefficient of thermal expansion of multi-phase composites.