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Increased strength and related mechanisms for mortars at cryogenic temperatures |
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| Affiliation: | 1. Department of Architectural Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea;2. Department of Civil Engineering, The University of British Columbia, 6250 Applied Science Lane, Vancouver, BC V6T 1Z4, Canada;1. College of Geology and Environment, Xi''an University of Science and Technology, Xi''an, Shaanxi 710054, PR China;2. Geological Research Institute for Coal Green Mining, Xi''an University of Science and Technology, Xi''an, Shaanxi 710054, PR China;3. Shaanxi Provincial Key Laboratory of Geological Support for Coal Green Exploitation, Xi''an, Shaanxi 710054, PR China;4. College of Civil Engineering, Tongji University, Shanghai 200092, PR China;5. College of Architecture and Civil Engineering, Xi''an University of Science and Technology, Xi''an, Shaanxi 710054, PR China |
| Abstract: | Properties of cement-based materials at cryogenic temperatures are quite different from those at room temperatures. The strength of mortars at cryogenic temperatures was experimentally studied and an empirical model was established. The freezing thermodynamic process of pore water and pore size distribution in mortars were characterized by differential scanning calorimeter (DSC) and thermoporometry (TPM), respectively. The relationship between the increased cryogenic strength and pore ice formation was discussed. The results showed that flexural strength of mortars increased at a higher rate than compressive strength. Water content and initial strength at room temperatures were the main factors influencing the cryogenic strength. Higher water content and higher initial strength resulted in higher cryogenic strength. Ice formation in pores is one of the main reasons for the mortar’s cryogenic strength increase. Nearly half of the water remained unfrozen in pores with radius less than 40 nm at −40 °C. Both ice formed in capillary pores and gel pores contributes to the strength increase observed at cryogenic temperatures. |
| Keywords: | Compressive strength Freezing Pore water Cryogenic temperatures Thermoporometry |
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