Masonry material characteristics such as compression stress-strain behaviour and the relationships between brick, mortar and masonry compressive strengths are required for the detailed analysis and assessment of masonry structures. These properties have been investigated previously, but most past studies were laboratory based and did not include within their scope the testing of existing masonry buildings. The present study aimed to characterise the compressive strength and the compression stress-strain relationship of vintage clay brick masonry used in New Zealand unreinforced masonry (URM) bearing wall buildings that were generally constructed between 1880 and 1940. Testing was performed on 45 masonry prisms that were extracted from eight New Zealand historic URM buildings and on 75 masonry prisms that were constructed in the laboratory using 14 different brick/mortar combinations. It was found that the laboratory constructed sample test results adequately replicated those from the field extracted samples, and predictive equations and a numerical compression stress-strain model for use in the detailed seismic assessment of URM buildings were developed based on the experimental results.

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The importance of sufficient masonry mortar joint bond strength when a structure is subjected to in-plane and out-of-plane loads has been emphasised by several authors. However, masonry unit/mortar bond strength is difficult to predict and performing mechanical tests on existing masonry buildings to determine masonry flexural bond and shear bond strengths is generally not practical, such that predictive expressions relating the masonry flexural bond and shear bond strengths to other masonry properties are desirable. Although relationships between brick/mortar bond and compressive strength have been investigated previously by researchers located in many different parts of the world, most of these studies were laboratory based and did not include the testing of existing masonry buildings within their scope. The present study aimed to characterise the material properties of New Zealand unreinforced clay brick masonry (URM) buildings that were generally built between 1880 and 1930, with in-situ testing and sample extraction performed on 6 heritage buildings. Masonry compression, bond wrench and shear bond tests were undertaken. The experimental results indicate that the masonry flexural bond strength and the bed joint cohesion can be satisfactorily related to the mortar compressive strength.

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