基于Mazars损伤模型评价不同粗糙度机制砂砂浆的抗裂性能

Assessment of Crack Resistance of Mortars Prepared from ManufacturedSands with Different Roughness Based on the Mazars Damage Model

采用8字模拉伸试验和平板约束开裂试验,结合数字图像相关法(DIC)测试了含不同粗糙度机制砂水泥砂浆的早期拉伸能力和非均匀变形。基于砂浆Mazars损伤模型,计算分析了砂浆的等效拉应变,统计了其中的非均匀变形和损伤场分布。研究发现,机制砂粗糙度增大能提高砂浆早期的拉伸能力,同时降低砂浆整体的收缩变形;砂浆由收缩变形引起的损伤主要分散在约束相周围,以砂浆-约束相界面为起点向砂浆发散,越靠近界面其损伤程度越大。综合考虑损伤面积和等效拉应变的影响,计算了砂浆的损伤因子,发现机制砂粗糙度增加到1.51时,损伤因子降低为0.0043ε,约束相间隙浆体的损伤区域基本消失,砂浆收缩开裂的风险下降。

The early tensile strength and non-uniform deformation of cement mortar containing manufactured sands with different roughness levels were investigated by the 8-shaped tension test and plate-constrained cracking test,combined with digital image correlation(DIC)technique.Based on the Mazars damage model,the equivalent tensile strain in mortar was calculated,and the distribution of non-uniform stress and damage field was statistically characterized.It was found that increasing the roughness of manufactured sand resulted in improved the early tensile strength of the mortar,accompanied by a reduction in overall shrinkage deformation.The damage induced by shrinkage deformation was primarily concentrated around the constrained phase,and propagating towards the mortar from the mortar-constrained phase interface.As the damage neared the interface between the mortar and restraining phase,the severity of the damage escalated.The damage index calculated form the damage area and the equivalent tensile strain in mortar.It was found that when the roughness of the manufactured sand increased to 1.51,the damage index decreased to 0.0043ε,and the damage area in the interfacial mortar between the restraining phases nearly disappeared,lead to low micro-cracking risk in the mortar.