Zhang Zhen, Rao Fengrui, Ye Guanbao, Liu Jiangting
Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education, Department of Geotechnical Engineering, Tongji University, Shanghai 200092, China.
Shanghai Construction No. 2 (Group) Co., Ltd., Shanghai 200090, China.
Materials (Basel). 2022 Feb 24;15(5):1711. doi: 10.3390/ma15051711.
Cement-based lightweight materials have received much attention recently in embankment backfill applications, the boundary of which is more close to a plane strain condition. To study the influence of plane strain condition on the behavior and void structure of cement-based lightweight material under cyclic loading, this paper conducted a series of compression tests on foamed cement pastes with densities of 700 and 900 kg/m subjected to static and cyclic loading under plane strain conditions. The X-CT technique was adopted to obtain the three-dimensional (3-D) void structures of the specimens before and after the loading tests. The results showed that the plane strain conditions yielded specimen compression strengths 30-50% higher than the unconfined conditions. The specimen integrity endured under load levels of less than 0.5, but failed after approximately 1000 cycles under a load level of 0.8, indicating that cyclic loading could accelerate the degradation of the specimena. The void structures of the specimens showed that the void volumes were featured bfatured an unimodal distribution with unimodal positions in a range of 0.1-0.2 mm. The unimodal position became higher with the increasing cyclic load level. Slices of the specimens after static and cyclic loading tests suggested that cyclic load could easily lead to the rupture of voids that then merge into bigger voids and the connection of voids forming cracks.
水泥基轻质材料近年来在路堤回填应用中备受关注，其边界更接近平面应变条件。为研究平面应变条件对循环加载下水泥基轻质材料性能和孔隙结构的影响，本文对密度为700和900kg/m³的泡沫水泥净浆在平面应变条件下进行了一系列静载和循环加载压缩试验。采用X射线计算机断层扫描（X-CT）技术获取加载试验前后试件的三维孔隙结构。结果表明，平面应变条件下试件的抗压强度比无侧限条件下高30%-50%。试件在荷载水平小于0.5时保持完整，但在荷载水平为0.8时经过约1000次循环后破坏，表明循环加载会加速试件的劣化。试件的孔隙结构表明，孔隙体积呈单峰分布，单峰位置在0.1-0.2mm范围内。随着循环荷载水平的增加，单峰位置升高。静载和循环加载试验后试件的切片表明，循环荷载容易导致孔隙破裂，进而合并成更大的孔隙，孔隙连通形成裂缝。
