Mechanical properties of alkali-activated concrete exposed to cryogenic temperature

As a promising and sustainable construction material, alkali-activated concrete (AAC) may be exposed to harsh cryogenic environments. However, the mechanical properties of AAC at cryogenic temperatures remain unexplored. This is probably the first study that focuses on the mechanical performances, i.e., compressive strength, elastic modulus, splitting tensile strength, fracture energy, characteristic length and fracture toughness of AAC exposed to cryogenic temperatures as low as -160 degrees C. According to the test results, the mechanical properties of the AAC enhanced dramatically as temperature decreased. Due to the high moisture content and water-accessible porosity, above hardened properties of AAC with lower strength grades were more susceptible to low temperatures. Compared to ordinary Portland cement-based concrete (OPCC) with similar strength grades, AAC exhibited superior mechanical characteristics at comparable temperatures. Based on the test data, empirical relations were proposed to correlate the mechanical performances of AAC and temperatures.