Mechanical behavior of steel fiber reinforced concrete at cryogenic temperatures: Characterization with 3D meso-scale modelling

To investigate the mechanical properties of SFRC (Steel Fiber Reinforced Concrete) in low-temperature environments, a 3D mesoscale model approach was employed to simulate the mechanical behavior of SFRC specimens at cryogenic temperatures. The model considers SFRC a multiphase material composed of mortar, aggregate, ITZ (Interface Transition Zone), and steel fiber. Using the mesoscale modelling, the damage pattern, stress-strain curve, load-deformation curve, dissipated energy, strength under compressive and splitting-tensile loadings, strength prediction formula as well as the flexural toughness of SFRC specimens with different steel fiber content at low temperatures were obtained and analyzed. The results show that the compressive/splitting tensile strength significantly increases with the decrease in temperature. The splitting tensile strength, the peak deformation as well, and the dissipated energy increase in the case of a greater steel fiber volume fraction while the improvement effect of fiber content is weaker with the decrease in temperature. A prediction formula that considers the coupling effect of fiber volume fraction and temperature on the tensile strength of concrete was proposed. The effect of steel fiber on compressive strength is not obvious regardless of temperature. The flexural toughness index of SFRC increases significantly with increased steel fiber content but is insensitive to temperature changes.