Action of Hydraulic Pressure on Portland Cement Mortars - Current Understanding and Related Progress of the First-Ever In-Situ Deep Sea Tests at a 3515 m Depth
Action of Hydraulic Pressure on Portland Cement Mortars - Current Understanding and Related Progress of the First-Ever In-Situ Deep Sea Tests at a 3515 m Depth
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DOI：
10.3151/jact.19.226
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发表时间：
2021-03
影响因子：
2
通讯作者：
Keisuke Takahashi;Y. Kawabata;Mari Kobayashi;Shinpei Gotoh;S. Nomura;T. Kasaya;M. Iwanami
中科院分区：
文献类型：
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作者：
Keisuke Takahashi;Y. Kawabata;Mari Kobayashi;Shinpei Gotoh;S. Nomura;T. Kasaya;M. Iwanami
为了实现水泥基材料在深海这一特殊极端环境中的利用，作者启动了一个旨在建立一个技术平台的项目，该平台具有用于监测和评估位于深海底部站点的水泥基材料的原位方法和系统。目前，世界上第一个现场试验正在南开海槽3515米深处进行，目的是研究波特兰水泥砂浆长期暴露于深海条件后的体积稳定性和微观结构的时间依赖性。本文综述了深海水压对水泥基材料影响的研究成果，在实验室规模上用波特兰水泥砂浆验证了短期水压的作用，并介绍了深海原位试验的最新进展。室内试验结果表明，在短期水压作用下，液态水的渗透和约束引起了尺寸变化，但在蠕变等应力作用下的时间依赖性行为尚未出现。在加压和减压过程后，监测水泥砂浆的增重、孔径分布、抗压强度和抗折强度的变化。
In order to realize the utilization of cement-based materials in the special extreme environment, the deep sea, the authors have launched a project targeted at creating a technology platform with in-situ methods and systems for monitoring and evaluating cement-based materials located at deep ocean bottom sites. The first in-situ test in the world with a view to investigating the time-dependence of the volumetric stability and microstructure of Portland cement mortar following its long-term exposure to deep-sea conditions is currently underway at a 3515-m depth in the Nankai Trough. This paper reviews previous studies about the influences of deep-sea hydraulic pressure on cement-based materials, verifies the action of short-term hydraulic pressure using Portland cement mortars on a laboratory scale, and introduces the ongoing progress of in-situ deep-sea tests. Results from laboratory tests indicate that dimensional changes were provoked by liquid water infiltration and confinement while under short-term hydraulic pressure, however, time-dependent behavior under stresses such as creep has not appeared. Weight gain, changes in pore-size distribution, compressive strength and bending strength of the cement mortar were monitored after pressurization and depressurization processes.