Cement mortar cracking under accelerated steel corrosion test: A mechanical and electrochemical model

Abstract

Corrosion of the embedded steel is one of the main degradation problems limiting the service life of reinforced and pre-stressed concrete structures. A model able to provide approximate predictions of the evolution of the cracking process can be useful for designing accelerated corrosion tests of reinforced cement mortar or concrete specimens. An electrochemical model has been used for describing the inner displacements and strains caused by the accumulation of steel corrosion products around the rebar during electrically accelerated corrosion tests of reinforced cement mortar specimens with simple geometries. Subsequently, a mechanical model using the XFEM-Based Crack Growth Simulation module of Ansys Software, has been implemented to describe the distribution of stresses in the cross-section of the specimens. The combined electrochemical and mechanical model has led to acceptable predictions of the time to appearance of the first surface crack and the evolution of crack width over time. This combined model, which needs only data of a few experimental parameters, and uses only readily accessible standard software, could easily be implemented with other experimental configurations. For a more realistic description of the distribution of the tensile stresses and of the whole cracking process, the model must consider the initiation of several cracks, at least eight, around the rebar perimeter. The inclusion in the model of higher number of cracks increases greatly the computation time and effort, and may lead to convergence difficulties.