Investigation of the mechanical behaviour of concrete with severe delayed ettringite formation expansion focusing on internal damage propagation under various compressive loading patterns
Investigation of the mechanical behaviour of concrete with severe delayed ettringite formation expansion focusing on internal damage propagation under various compressive loading patterns
复制标题
DOI：
10.1016/j.cemconcomp.2022.104433
复制
发表时间：
2022-02
影响因子：
10.5
通讯作者：
Nirmal Raj Joshi;A. Matsumoto;S. Asamoto;T. Miura;Y. Kawabata
中科院分区：
文献类型：
--
作者：
Nirmal Raj Joshi;A. Matsumoto;S. Asamoto;T. Miura;Y. Kawabata
钙矾石形成延迟 (DEF) 导致的膨胀会导致混凝土强度严重恶化；与内部损坏相关的失效过程仍不清楚。在本研究中，论证了预先存在的 DEF 裂纹对压缩破坏过程的影响。 DEF 膨胀大于 2% 的混凝土试件在单调、阶梯、循环和持续加载模式下进行测试，提供应力-应变关系。使用 X 射线 CT 图像对由于载荷引起的内部裂纹扩展进行量化。即使在低应力水平下也会发生较大的塑性应变。失效时的峰值应力和应变几乎与载荷历史无关。随着载荷的增加，集料周围形成的间隙分别在载荷方向和垂直方向上闭合和打开，从而有助于塑性应变积累。在高应力水平下，裂缝沿着骨料界面逐渐相互连接，导致样本失效。在循环或持续载荷下逐渐闭合间隙减少了相同应力下的额外塑性变形。
Expansion due to delayed ettringite formation (DEF) can cause severe concrete strength deterioration; the failure process related to internal damage remains unclear. In this study, the influence of pre-existing DEF cracks on the compressive failure process was demonstrated. Concrete specimens with DEF expansions greater than 2% were tested under monotonic, step, cyclic, and sustained loading patterns, providing stress–strain relationships. Internal crack propagation due to loading was quantified using X-ray CT images. Large plastic strains occurred, even at low stress levels. Peak stress and strain at failure were almost independent of the loading history. Gaps formed around the aggregate with increased loading were closed and opened in the loading and perpendicular directions, respectively, contributing to plastic strain accumulation. Gradual interconnection of cracks along the aggregate interfaces at high stress levels led to specimen failure. Gradual gap closing under cyclic or sustained loading reduced additional plastic deformation under the same stress.