Poro-elastic-plastic model for cement-based materials subjected to freeze-thaw cycles

This paper presents a poro-elastic-plastic model to predict changes in the pore structure and reduction in the mechanical property of cement-based materials when subjected to freeze-thaw cycles. In this model, the macroscopic porous material is assumed composed of a series of microscopic spherical units, thermodynamics of in-pore crystallization and unsaturated poroelasticity are employed to compute the frost stresses originated from pores (i.e., pressure in liquid and pressure in crystals), nonlinear elastic-plastic behavior is incorporated to analyze the irreversible deformation of the microscopic spherical units. Pore structure and hardness measurements are carried out to determine and verify the parameters about elasticity and plasticity. Finally, the proposed model is applied to a cement paste to predict its porosity, pore size distribution and damage factor after a certain number of freeze-thaw cycles, and influences of pore geometry on the freeze-thaw damage are discussed on the hypotheses of cylindrical pores and spherical pores, respectively. (C) 2018 Elsevier Ltd. All rights reserved.