Damage mechanisms in porous building materials due to salt crystallization: formulation of equivalent materials for masonry

An equivalent material approach is presented for the computation of the elastic properties of brick masonry and for the assessment of salt crystallization in masonry structures. A stacked brick-mortar system consisting of a series of parallel layers which behave elastically is introduced. This is extended such that masonry with two sets of mortar joints (bed and head joints) can be represented by an equivalent homogeneous orthotropic elastic material. It is then extended to salt deteriorated brick masonry by including salt crystals induced within the pores. In terms of the elastic properties of the brick and mortar, as well as relative thicknesses, expressions for the equivalent material's elastic properties are derived. The mechanical properties of salt deteriorated masonry are computed in terms of effective porosity and saturation ratio. Using this derivation, the stresses in the brick-and-mortar joints are calculated for a masonry wall partial deteriorated by salt and subjected to thermal stress variation.