Mode Ⅰ fracture behaviors of concrete at low temperatures

Abstract

This paper investigated the cubic compressive strength and mode Ⅰ fracture behaviors of concrete at temperatures between 20 °C and −80 °C. 144 concrete cubes and 72 three-point bending notched concrete beams were prepared and classified into six groups on the water/cement ratio, water content and type of concrete, respectively. The fracture toughness, fracture energy and characteristic length of concrete at temperatures between 20 °C and −80 °C were determined. Results showed that the crack resistance and ultimate bearing capacity of three-point bending concrete beams increased at low temperatures. As the temperature falls from 20 °C to −80 °C, the fracture toughness and fracture energy of concrete significantly increase, but its characteristic length is reduced. According to the experimental results and regression analysis, three empirical formulae were established to determine the concrete fracture energy at low temperatures. Finally, the extended finite element method was applied to investigate the failure mechanism of three-point bending beams, and parametric analysis was conducted to study the influencing mechanism of critical parameters on fracture behaviors of three-point bending concrete beams.