Physicochemical properties of the Portland cement-based mortar exposed to deep seafloor conditions at a depth of 1680 m
Physicochemical properties of the Portland cement-based mortar exposed to deep seafloor conditions at a depth of 1680 m
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DOI：
10.1016/j.cemconres.2020.106335
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发表时间：
2021-01-15
影响因子：
11.4
通讯作者：
Kawabata, Yuichiro
中科院分区：
文献类型：
--
作者：
Kobayashi, Mari;Takahashi, Keisuke;Kawabata, Yuichiro
要在海洋技术方面取得突破，就需要开发淹没在深海环境中的基础设施，深海环境对水泥基材料的物理化学影响与浅海环境有很大不同。然而，很少有研究集中在水泥基材料经受深海条件。研究了水泥砂浆在1680 m海底放置608 d后抗压强度和相组成的变化。从海底打捞上来的砂浆样本显示出严重的可见损坏，包括软化的泥状结构和显著降低的抗压强度。所获得的X射线衍射，扫描电子显微镜，和核磁共振数据显示，氢氧化钙的溶解，脱钙（铝）硅酸盐水合物，形成水镁石，镁（铝）硅酸盐水合物，水滑石样相，碳硫硅钙石，钙矾石可能有助于砂浆的解体，这可能会进一步加速由深海环境的低温。
Achieving breakthroughs in marine technologies requires the development of infrastructures submerged in deepsea environments, whose physicochemical effects on cement-based materials considerably differ from those of shallow seas. However, very few studies focused on the cement-based materials subjected to deep-sea conditions. This work investigates the changes in the compressive strength and phase composition of the cement mortar kept on the seafloor with a depth of 1680 m for 608 d. The mortar specimens salvaged from the seafloor exhibited severe visible damages, including softened mashy structures and significantly decreased compressive strengths. The obtained X-ray diffraction, scanning electron microscopy, and nuclear magnetic resonance data revealed that the dissolution of portlandite, decalcification of calcium (alumino) silicate hydrate, and formation of brucite, magnesium (alumino) silicate hydrate, a hydrotalcite-like phase, thaumasite, and ettringite likely contributed to the disintegration of mortar, which could be further accelerated by the low temperature of the deep-sea environment.