Modeling and Mesoscale Simulation of Ice-Strengthened Mechanical Properties of Concrete at Low Temperatures

Abstract

Formation of ice plays a key role in the behavior of concrete materials at low temperatures in cold and wet regions. The internal stresses generated during the freeze-thaw process could cause serious damage and other durability problems to concrete structures. However, just concerning the stage while the temperature is below 0°C, ice could reduce the stress concentration in the porous matrix by filling the capillary pores and result in a significant increase of elastic modulus and strength, which is usually beneficial for concrete under mechanical loads (either static or fatigue). Meanwhile, pore pressures at low temperatures will also play an important role in either accelerating or delaying the microcracking. In order to establish a mesoscale approach [which usually treats concrete as a composition of coarse aggregate, mortar, and interfacial transition zone (ITZ) between them] based on the rigid-body spring method (RBSM) for the aforementioned issues, in the first stage, the ice-strengthened elastic properties of the mortar are estimated based on multiscale continuous micromechanics. Then a mesoscale model based on RBSM is developed to simulate the nonlinear mechanical behavior under uniaxial compression, tension, and splitting for concrete, in which the ice-strengthened elastic properties in mortar and ITZ, as well as the pore pressures caused by ice formation, are taken into consideration. The range and tendency of the simulated strength values agree well with experimental data.