Finite-Element Analysis of Chemical Transport and Reinforcement Corrosion-Induced Cracking in Variably Saturated Heterogeneous Concrete

Abstract

Reinforcement corrosion owing to chemical attack could lead to premature steel-mortar debonding, concrete cracking, and catastrophic failure of structures if not well attended. In conventional design and maintenance practices, heterogeneous concrete matrix is commonly treated as a homogeneous medium when the evolution of chemical ingress and concrete cracking need to be determined. Such oversimplification has caused significantly inaccurate prediction and evaluation of structural service life. This paper presents a finite-element (FE) model developed to evaluate the service life of reinforced concrete (RC) structures in three key steps: chemical ingress, steel corrosion, and concrete cracking. The mass conservation principle is employed in the first step to model the ingress of multiple chemical species into variably saturated heterogeneous concrete matrix. By using Faraday’s law, steel corrosion and the incurred diametric expansion are then formulated as a transient displacement boundary condition for subsequent analysis of concrete cracking. The cracking pattern of concrete under the expansion force of corrosion products is finally characterized by using a cohesive-fracture approach. The FE model is validated with laboratory experiments.