饱和状态下水泥浆体的微观结构冰冻损伤模型

摘要

为了研究水转化为冰所带来的体积膨胀对水泥浆体的微观结构的危害,量化微观结构的内部损伤,建立了一个饱水状态下水泥浆体的冰冻破坏模型.首先使用模拟水泥浆体微观结构的数值模型(HYMOSTRUC)生成一个模拟结构,根据这个模拟结构中的孔结构,分析水分在孔隙中发生的相转变;将含有冰、水和水化产物的水泥浆体微观模拟结构转变为三维格构结构,并把水分发生相变时产生的体积膨胀引入其中,从而分析格构结构的受力及断裂;最后得到水泥浆体微结构内部微裂缝的分布.该模型真实反映了冰冻作用对微观结构的破坏,模拟结果显示微裂缝产生在由水转变为冰的孔隙周围的抗拉强度低的固相水化产物中.%In order to investigate the microstructural change of cement paste caused by the volume expansion of water-to-ice change and to quantify the internal damage of the microstructure, a numerical frost damage model of saturated cement paste is proposed. A virtual microstructure of cement paste is first obtained by use of a numerical model namely HYMOSTRUC (hydration, morphology and structure). Then according to the pore structure of the virtual microstructure of cement paste, the phase change of water in pores is analyzed. The next is to convert the microstructure of cement paste containing ice, water and hydration products into a three-dimensional (3D) lattice structure. The volumetric expansion of water-to-ice is imposed in the 3D lattice structure. Thus the fracturing process of the 3D lattice structure is obtained and the distribution of micro-cracks in the microstructure of cement paste is revealed. The modeling shows that the micro-cracks occur in the hydration products of low tensile strength around the pores filled with ice.