McMaster University, Hamilton, Ontario
and G.N. PANDE University College of Swansea


This paper presents a theoretical basis for the calculation of compressive and tensile strengths of saturated masonry materials, that is materials of which the masonry units, such as clay bricks or concrete blocks, are made. The strength in the wet state is estimated based on an effective stress principle and the kinematic constraint of undrained deformation of the saturated material-First, the estimates based on TERZAGHI’S effective stress principle, commonly used in soil mechanics, are derived. These estimates seem to be inaccurate, in view of the existing experimental data. A new effective stress principle, applicable to masonry materials, is then proposed. This principle invokes porosity as an additional material constant. The numerical predictions of compressive and tensile strength of saturated materials, based on this principle, appear to be more accurate.