A comparative study in flexural tensile bond strength normal to bed joints between masonry cement mortars and Portland cement lime mortars

Four brands each of masonry cements type S and N were selected to produce mortars for comparison to Portland cement lime mortars of types S, N, and O. Sixteen masonry prism specimens in stack-bond of five units high along with three samples of mortar cubes for compressive strength were made for each mix. 88 specimens were tested in flexure by the bond wrench method (ASTM C1072-86) after 28 days of air curing in the laboratory. Results show Portland cement lime mortars provide better flexural bond strength than equivalent masonry cement mortars. The compressive strengths of mortar cubes show no correlation to flexural bond strength results. The comparative study between solid units and cored units revealed neither is remarkably superior to the other. Solid units performed more consistently as indicated by a lower variation in test results. (Abstract shortened with permission of author.).