Compressive behaviour of fired-clay brick and lime mortar masonry components in dry and wet conditions

Abstract

This paper examines the fundamental mechanical properties of masonry elements incorporating fired-clay bricks and hydraulic lime mortars under ambient-dry and wet conditions, corresponding to 48 h submersion in water. In addition to complementary material characterisation assessments, two types of specimens are tested: cylindrical cores in compression, and wall elements in compression. Overall, a detailed account of more than 50 tests is given. Apart from conventional measurements, the use of digital image correlation techniques enables a detailed assessment of the influence of moisture on the constitutive response, confinement effects and mechanical properties of masonry components. The uniaxial compressive strengths of wet brick elements and brick–mortar components, resulting from tests on cylindrical cores with height-to-depth ratios of around two, are shown to be 13–18% lower than those in ambient-dry conditions. The tests also show that enhanced confinement levels in brick units mobilise 67–92% higher strengths than in the corresponding unconfined cylinders. Moreover, experimental observations indicate that the presence of significant confinement reduces the influence of moisture on the mechanical properties as a function of the brick and mortar joint thickness and their relative stiffness. As a result, the failure of wet masonry walls in compression is found to be only marginally lower than those in ambient-dry conditions. Based on the test results, the influence of moisture on the constitutive response and mechanical properties of masonry components is discussed, and considerations for practical application are highlighted.