Shear-Compression Failure Envelopes for Clay Brick Lime Mortar Masonry Under Wet and Dry Conditions

This study describes an experimental investigation into the fundamental mechanical properties of masonry incorporating fired-clay bricks and hydraulic lime mortars under ambient-dry and wet conditions, used in many historic structures. The investigation includes tests on cylindrical cores in compression, square panels in diagonal compression and triplets in shear. Apart from conventional measurements, the use of digital image correlation techniques enables a detailed assessment of the influence of moisture on the constitutive properties and on the response kinematics of the member, including behaviour characteristics of the brick-mortar interfaces, crack propagation in tension and confinement effects in compression. The tests results show that on average the uniaxial compressive strength of wet brick-mortar cylinders is about 15% lower than their dry counterparts, whilst the shear strength of wet triplets is about 20% lower than of those in dry conditions. The diagonal tension strength of wet panels depends largely on the mortar properties and is about 30% lower on average than that of the dry panels. Based on the test results, the material shear-compression strength envelopes for wet and dry masonry are evaluated and compared with existing assessment models.