Over the past decades, concrete material has been widely applied in the engineering structures of low temperature environment increasingly. The scientific understanding of the mechanical properties of concrete materials and components at cryogenic temperatures is the basis for the safety design of engineering structures under the extreme low temperature environment. However, the existing test conditions and measurement technology at low temperatures limit the researches on cryogenic concrete. In order to further investigate the mechanical performance and the corresponding failure mechanism of cryogenic concrete, Professor JIN Liu and his team developed a comprehensive mesoscale modelling approach with thermo-mechanical coupling. In the mesoscale model, accounting for the meso-structure characteristics and ice-strengthening effect, the cryogenic concrete was modelled with coarse aggregates, mortar matrix as well as the equivalent ice, and a 2-stage sequentially thermo-mechanical coupling analysis was conducted. The first stage was heat conduction analysis of cryogenic concrete which aimed to obtain the temperature and stress field distributions and establish the relationship between temperature and stress. Based on the heat conduction, considering the temperature-dependency of mechanical parameters of meso-components, mechanical response analysis of concrete was subsequently conducted.

In this study, the uniaxial compressive failure behaviors of concrete at various low temperatures were captured. The influences of environmental temperature, moisture content and specimen size on uniaxial compressive failures of cryogenic concrete were discussed in terms of failure patterns, deformation curves, elastic-modulus, failure strengths as well as energy absorption. The action mechanism of pore ice on crack development and strength enhancement at low temperatures has been revealed. A good consistency between the simulations and tests verified the effectiveness of the mesoscale modelling approach with thermo-mechanical coupling, which contributes to developing the soundness assessment for cryogenic concrete materials. The results have recently been published in the Cold Regions Science and Technology.

The first author of this study is Ph.D. Student YU Wenxuan of BJUT. The work was done in collaboration with Prof. JIN Liu and ZHANG Renbo of BJUT.

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