针、片状骨料对混凝土单轴拉压破坏影响细观模拟

Meso-simulation on effect of acicular and flaky aggregate on uniaxialtensile-compressive failure of concrete

为了研究针、片状骨料对混凝土力学性能的影响,建立细观层次的混凝土随机骨料三维数值模型,以粗骨料中针、片状颗粒的粒形和体积占比为变量,对含针、片状骨料二级配立方体混凝土模型在单轴受拉和单轴受压荷载作用下的破坏过程进行模拟研究。结果表明:①混凝土的抗拉、抗压强度随着针、片状骨料含量的增加而降低,针、片状骨料含量对混凝土抗拉强度的影响比抗压强度小。②针、片状骨料对混凝土在单轴拉压荷载下的破坏影响主要与其排列方式有关,具有较大横向骨料-砂浆交界面的骨料对混凝土拉伸损伤的产生和发展起到主导影响,在单轴受压荷载作用下,混凝土中竖向或者近似竖向排列的针、片状骨料表面更容易产生裂缝。③针、片状骨料对混凝土的强度和破坏过程均产生不利影响,影响大小的排序为片状骨料>针状骨料>针、片状骨料混合。

In order to study the influence of acicular and flaky aggregate on the mechanical properties of concrete,a three-dimensional numerical model of concrete random aggregate at the meso-level was established in this study.The particle shape and volume ratio of deformed particles in coarse aggregate were taken as variables,the failure process of two graded aggregate concrete cubic model with acicular and flaky aggregate under uniaxial tension and uniaxial compression load was simulated.The results show that:①The tensile and compressive strength of concrete will decrease with the increasing of acicular and flaky aggregate content.The effect of acicular and flaky aggregate content on the tensile strength of concrete is smaller than that of compressive strength.②The influence of acicular and flaky aggregate on the failure of concrete under uniaxial tensile and compressive loads is mainly related to its arrangement.The aggregate with larger transverse aggregate-mortar interface plays a dominant role in the generation and development of concrete tensile damage.The surface of acicular and flaky aggregate vertically or approximately vertically placed in concrete is more likely to crack under uniaxial compressive load.③The acicular and flaky aggregate have adverse effects on the strength and failure process of concrete,and the influence from big to small is flaky aggregate>acicular aggregate>mixed aggregate.