Open AccessPhysical properties of portland cement based concrete exposed at a depth of 3520 m in the Nankai Trough
Author(s) -
Shun Nomura,
Takafumi Kasaya,
Yuki Sakoi,
Hisashi Fukada,
Akira Matsumoto
Publication year - 2022
Publication title -
acta polytechnica ctu proceedings
Language(s) - English
Resource type - Journals
ISSN - 2336-5382
DOI - 10.14311/app.2022.33.0411
Subject(s) - portland cement , durability , seawater , submarine , cement , geology , trough (economics) , environmental science , geotechnical engineering , materials science , oceanography , metallurgy , composite material , economics , macroeconomics
Concrete is widely used in large-scale construction of submarine infrastructure because of its high strength, durability, and ease of handling. However, knowledge of its durability in deep seawater is lacking. In the deep sea, materials are exposed to high pressures and low temperatures, which may cause early deterioration of concrete over time. Concrete materials may also be affected by the chemical composition of seawater, which induces the leaching of calcium. In situ exposure tests are therefore important for understanding degradation processes in the deep sea. In this study, Portland cement based concrete specimens were placed at a depth of 3520 m on the northern edge of the Nankai Trough in 2018 and retrieved in 2019, in the deepest exposure testing conducted to date. Here we provide an outline of the tests, describe the physical properties of materials exposed to deep seawater, freshwater, and air, and discuss possible concrete degradation mechanisms.