骨料形状对混凝土拉伸强度的影响

Influence of aggregate shape on tensile strength of concrete

运用Monte-Carlo方法模拟产生了由骨料、水泥砂浆基体和两者之间的胶结带组成的三相复合材料混凝土试件,采用各向同性的Mazars损伤演化模型描述混凝土细观各相弹性损伤退化过程,利用有限元方法分别进行了混凝土二、三、四级配圆形、多边形骨料试件的单轴拉伸数值模拟.试验结果表明:同一级配任意多边形骨料试件的极限承载力总体上要大于圆形骨料试件的承载能力;二、三、四级配混凝土试件强度依次递减;在应力-应变曲线的软化阶段,圆形骨料较多边形骨料试件软化曲线平缓;多边形骨料混凝土试件的脆性指数较圆形骨料混凝土试件的脆性指数高.

Concrete is conceptualized as a three-phase composite consisting of mortar, aggregate and their interface. The Monte-Carlo method is used to generate the random aggregate model, the Mazars isotropic damage evolution model is employed to describe the meso-mechanics deterioration of elastic damage of the concrete, and the finite element method is adopted to numerically simulate the uniaxial tension tests of two, three and four grade specimens with circular and polygonal aggregates, respectively. The results show that the ultimate load capacity of an arbitrary polygonal aggregate specimen is greater than that of a circular one of the same grade, and that the concrete strength from two grade up to four grade decreases in sequence. It is also concluded that, during the softening stage of the stress-strain curve, the softening curves of the circular aggregate specimens are gentler than those of the polygonal ones, and that the brittleness indexes of the polygonal aggregate specimens are larger than those of the circular ones.