基于多尺度方法的高性能混凝土自收缩机理研究

Compared to ordinary concrete, the high performance concrete (HPC) shows great advantages in both strength and durability. Due to the high content of binders, the early age self-desiccation as well as autogenous shrinkage of HPC is much more pronounced. As a result of the intrinsic complexity, the mechanism of autogenous shrinkage has not been fully understood yet for HPC. Herewith, based on the integrated cement hydration model and the porous media mechanics, we shall perform a multiscale study towards the investigation of the mechanism of autogenous shrinkage for HPC. As expected, the multiscale study shall benefit a lot to the long durability and service life for HPC.

相较于普通混凝土，高性能混凝土兼顾优异的强度和耐久性。由于胶凝材料含量高，高性能混凝土存在一个不容忽视的问题，即水化早期的自干燥效应及其导致的自收缩行为。由于材料本身的复杂性，高性能混凝土自收缩的机理研究还存在一定的不足。本项目结合水泥水化模型和多孔介质力学模型，基于多尺度方法深入探讨高性能混凝土自收缩的内在机理。本项目对于确保高性能混凝土材料的耐久性和服役寿命具有重要意义。

本项目首先全面考察了基体微观结构的分形几何特征，包括体积分形、孔隙-固相界面分形以及固相质量分形，提出了模拟分形微观结构的一般化方法。其次，结合MIP测试结果，本项目进一步阐明固相分形是基体中最有可能存在的分形模式，基于一般化分形方法，提出了模拟微观结构的固相分形模型。最后，本项目在模拟基体分形微观结构的基础上，提出结合有限元方法预测基体的弹性模量，为进一步阐明混凝土的收缩机理做铺垫。