Multiscale Modeling and Simulation of Ice-Strengthening Effects in Mesocracks of Saturated Frost-Damaged Concrete under Freezing Temperature

Abstract

It is widely known that concrete structures in cold and humid environments usually suffer frost damage and thus deteriorate faster, especially those structures without using air-entraining agents and with exposure to excessive moisture. Most available research on concrete under a freezing environment could be roughly categorized into: (1) intact concrete under freezing temperature where the ice-strengthening effect in pores was predominant; and (2) frost-damaged under room temperature where the damaging effect because of mesocracks was predominant. In fact, once the mesocracks of frost-damaged concrete are filled with water and the water freezes into ice under low temperature, the ice could provide an extra strengthening effect to the porous skeleton of concrete materials. In other words, both strengthening and damaging effect exist for frost-damaged concrete under freezing temperature. Specifically, it is of great importance to clarify such ice-strengthening effects in mesocracks so that the mechanical performances of the frost-damaged concrete under freezing temperature could be further studied. As the first step, the fully saturated case is the focus to develop rational and reliable models for further exploration and extension to the partially saturated case. In this paper, the authors develop comprehensive multiscale models that consider the damaging effect of ice formation on concrete as well as the strengthening effect of ice-filled pores and ice-filled mesocracks. The developed models are implemented into a discrete numerical application, then rigid body and spring model simulations are conducted. Experiments including uniaxial compression and splitting tension of concrete specimens are also executed to demonstrate the ice-strengthening phenomenon in mesocracks’ proposed models as well as the simulations by the developed program.