Mechanical characterization of Eastern Canada’s field-extracted old clay brick masonry constituents and assemblies via experimental testing

Canada is one of the few earthquake-prone countries worldwide without a performance-based building code, partly because of lacking reference mechanical values for its existing structures. This is particularly concerning for Eastern Canada’s unreinforced masonry (URM), whose constituent- and assembly-scale mechanical behaviour is mostly still unknown. This work is the first in Canada to quantify experimentally, in controlled conditions, the uniaxial compression or shear-compression (referred to simply as shear hereinafter) responses of 19th-20th century field-extracted clay brick URM constituents (bricks, mortars) and assemblies (mortared brick masonry prisms) – essential yet previously missing data for conducting informed structural assessments. First, masonry constituents are tested individually to infer physical, elastic and plastic properties using compression tests of bricks and double punch tests of mortars. Then, under uniaxial compression (ASTM C1314), masonry assemblies were subjected to monotonic or cyclic loading for measuring Young’s modulus (680–2740 MPa), strength (4.2–14.1 MPa) and compression fracture energy (17.3–65.2 N/mm²) parameters – mixed joint-brick failures were often observed. Shear tests (EN 1052–3) were conducted on masonry assemblies at three distinct levels of precompression (0.2, 0.6, 1.0 MPa), yielding shear modulus (341–626 MPa), friction coefficient (0.44–0.69), dilatancy (1.3–30.6) and cohesion (0.1–0.2 MPa), as well as Mode II fracture energy (0.07–0.49 Nmm/mm²), exhibiting behaviours mostly governed by dry friction and joint sliding. This paper also provides first recommendations for predictive equations useful in design, including a shear/Young’s modulus ratio, a correlation equation between masonry Young’s modulus and compressive strength and an equation estimating masonry compressive strength using constituent values.