Wetting and Drying of Concrete: Modelling and Finite Element Formulation for Stable Convergence

The simulation of moisture movement in concrete is vital for estimating its durability performance under the given conditions of service. A robust analysis of the nonlinear phenomenon relies on the implementation of an efficient numerical algorithm. This entails a comprehension of the underlying mathematical models, the numerical analysis scheme and the related issues of stability and convergence. This paper describes a computational scheme to facilitate the estimation of moisture distribution in concrete subjected to wetting–drying exposure due to intermittent rains, an exposure type which severely impairs the durability performance of structural concrete under tropical climatic conditions. Beginning with a brief review of the conventional moisture transport models for concrete, this paper proposes a modified model using dimensionless parameters, which enhances the computational efficiency of the delineated scheme. This paper also describes the formulation of a one-dimensional, nonlinear finite element scheme for the modified model and discusses the issue of numerical oscillations concomitant to the numerical analysis of the problem. The suitability of the first-order element in providing stable convergence when implemented in conjunction with a lumped-mass scheme has been mathematically interpreted. The validity of the delineated proposition has been illustrated using a test problem.