机制砂砂浆界面过渡区特性研究

Characteristics of Interfacial Transition Zone in Manufactured Sand Mortar

研究机制砂砂浆界面过渡区特性对于提升机制砂砂浆强度与耐久性具有重要意义。通过扫描电子显微镜(SEM)、纳米压痕和三维图像相关(3D-DIC)技术观测了河砂砂浆和机制砂砂浆的界面微观结构、微区力学强度和非均匀变形。结果表明,机制砂砂浆的界面过渡区宽度大于河砂砂浆,但砂浆中细骨料颗粒与浆体的界面裂缝却更小,同时机制砂棱角位置易产生微裂纹。机制砂的界面过渡区弹性模量略高于河砂,说明机制砂能一定程度削弱骨料的边壁效应。砂岩机制砂砂浆的收缩变形非均匀性最大,其内部出现较大的拉伸应变,最终引起了更严重的损伤分布,这表明细骨料中刀片状颗粒占比偏多会增大砂浆局部开裂风险。

The study of interfacial transition zone characteristics in manufactured sand mortar is of great significance in enhancing the strength and durability of manufactured sand mortar.The interface microstructure,microzone mechanical strength,and non-uniform deformation of mortar composed of river sand and manufactured sand were examined through scanning electron microscopy(SEM),nanoindentation,and three-dimensional digital image correlation(3D-DIC)techniques.The results indicate that the width of the interfacial transition zone in manufactured sand mortar exceeds that in river sand mortar.Nevertheless,the interface cracks between fine aggregate particles and mortar matrix are smaller in manufactured sand mortar.Notably,microcracks are prone to occurring at the edges of manufactured sand particles.The elastic modulus of the interfacial transition zone in manufactured sand is slightly higher than that in river sand,suggesting that manufactured sand can mitigate the edge effect of aggregates to a certain extent.The non-uniformity of shrinkage deformation is most conspicuous in sandstone manufactured sand mortar,displaying larger internal tensile strains,ultimately leading to a more severe distribution of damage.This implies that an excessive proportion of blade-shaped particles in fine aggregates may heighten the risk of cracking in mortar.