New test for determination of masonry tensile bond strength

The bond strength between masonry units and mortar has been of considerable interest to researchers for some time. The flexural bond strength of masonry in particular is needed for the design of masonry walls subjected to horizontal forces applied normal to the face of the wall, such as wind forces. Researchers and standards have suggested different kinds of specimens and test procedures to determine the flexural bond strength. These include the test on wallettes (small walls), the bond wrench test, the Brench test, the direct tensile test, and the crossed couplet test. Each of these tests has its own drawbacks and problems. This paper presents a test method to determine the flexural bond strength, f(fb), by bending. The test could be used for laboratory research to investigate the many factors affecting bond strength and also for deriving design values for masonry standards. The specimen is constructed from two brick units in a Z-shaped configuration, and three-point loading induces a flexural bond failure parallel to the bed joint. Three different types of clay brick, one calcium silicate brick, and three different types of mortar were used in the experimental program. The results derived show that the proposed new specimen and test procedure are capable of determining the flexural bond strength easily and accurately.