Effect Mechanism of Ice Crystals on Mechanical Properties of Shale Ceramsite Concrete

To investigate the mechanism responsible for the embrittlement of concretes containing lightweight aggregates at cryogenic temperatures, a series of experiments were performed on all-lightweight shale ceramsite concrete (ALWSCC) and icicles at temperatures from -5 to -15 °C. The mechanical properties of ALWSCC specimens at cryogenic temperatures were analysed, the dependence of cryogenic mechanical properties on ice crystal volume and freezing temperature was also investigated. The Hansen model was used to invert the elastic modulus of ice crystals by a step-bystep approach. Results show that the compressive strength of ALWSCC specimens increases with the increasing volume fraction of ice crystals, and the strengthening effect gradually decreases after the ice crystal volume fraction exceeds 16.5%. The cubic compressive strength of ALWSCC specimens with ice crystals is more sensitive to freezing temperatures than that of dried ALWSCC specimens. Shear failure occurs when icicles are compressed, and the density and strength of ice increase with decreasing temperature below the freezing point. The elastic modulus of ice crystals is much higher than that of icicles at the same temperature, showing a huge size effect, and the ratio of the elastic modulus is less affected by temperature. The conclusions obtained in this study are important for understanding the mechanism of variation in the material properties of lightweight aggregate concrete in regions that experience cryogenic temperatures © 2021,Journal of Engineering Science and Technology Review. All rights reserved