Mesoscale modelling of compressive fracture failure of cryogenic concrete considering ice-strengthening effect: Fid-Bau Portal

Mesoscale modelling of compressive fracture failure of cryogenic concrete considering ice-strengthening effect

Yu, Wenxuan / Jin, Liu / Zhang, Renbo / Du, Xiuli

Abstract This paper proposes a comprehensive mesoscale modelling approach with thermo-mechanical coupling, accounting for the meso-structure characteristics and ice-strengthening effect to capture the compressive mechanical performances of concrete at various low temperatures. Meso-structure of cryogenic concrete composed coarse aggregates, mortar matrix and the equivalent ice was modelled and a 2-stage numerical analysis was conducted. The first stage was heat conduction analysis of cryogenic concrete which aimed to obtain the temperature and stress field distributions. Based on the heat conduction, uniaxial compressive failure analysis was subsequently conducted, which discussed the influences of environmental temperature, moisture content and specimen size. Results show that the ice can directly resist partial external load at the initial stage of compressive loading and the expansion of ice produces prestress on the surrounding mortar matrix which will suffer a multiaxial stress state. Consequently, the compressive strength, elastic-modulus as well as energy absorption of concrete are enhanced with the dropping temperature, showing a low temperature strengthening effect which is enhanced as the moisture content increases or the specimen size decreases. A good consistency between the simulations and tests indicates that the established mesoscale modelling approach can effectively reproduce the compressive fracture failure behaviour of cryogenic concrete, which contributes to developing the soundness assessment for cryogenic concrete materials.

Highlights • A sequentially coupled thermal-mechanical mesoscale model for cryogenic concrete was developed. • Non-linear mechanical responses of cryogenic concrete under uniaxial compression were simulated. • Failure mechanism of low temperature strengthening effect was analyzed considering the ice effect. • Influences of environmental temperature, moisture content and specimen size were investigated.