A numerical formulation for moisture migration in masonry

Abstract

The moisture content and migration in cementitious materials determine its time dependent response. Much research has been do ne over the last decades to gain insight in these phenomena and to distinguish between true and apparent mechanisms of creep and shrinkage. However, experimentally as well as computationally much remains to be done to characterise the indentified role players, for instance, true material shrinkage, stress-induced shrinkage, basic creep and the coupled effect of cracking and accelerated moisture migration. This contribution addresses these issues. A numerical model for the finite element analysis of creep, shrinkage and cracking in cementitious materials has been described in an accompanying report (Van Zijl 1999). Here, a model is elaborated tor analysing the moisture migration, the underlying mechanism of shrinkage and creep. The coupling with the mechanical analysis is also described. The material of interest is masonry, to be regarded as a particular cementitious concretelike material. Existing experimental data on masonry is employed tor the model parameter estimation and the validation. However, the experiments were not devised to distinguish between the different phenomena included in the numerical model. This excludes the possibility of the estimation of parameters even by an inverse approach. For this reason an experimental program is proposed with specific tests on small specimens for determining the model parameters and separate tests of wall parts on the meso-scale tor the validation of the model.