Enhancement of brick-mortar shear bond strength using environmental friendly mortars

Abstract

Usage of masonry system in many regions of the world like the Eastern Mediterranean, the Middle East, India, and China is still significantly high, despite their highly energy and intensive emission. Most of the failures in this system are caused by low ductility of cement mortars. This type of failure could be seen in masonry structures in areas in east Iran after Kermanshah earthquake in 2017. The present study investigates the shear bond characteristics of structures constructed by masonry using green materials. “Taftan” natural pozzolan and two types of rice husk ash (RHA) were used in mix design of used mortars as green materials. In this investigation, a modified direct shear test (DST) device was used to determine brick-mortar shear bond strength. The proposed method of applying DST has the advantages of determining pure bond characteristics and applying various normal loads. For this purpose, two bricks were bonded by each type of mortar and then subjected to the shear load. Direct shear tests were performed on nine different types of mortars with different normal loads. The effect of increasing shear bond strength over time was also studied. Finally, friction angle and cohesion of each system were determined. The test results showed that waste materials such as RHA in mortar could be considered as appropriate and beneficial mortar additives. Using these additives resulted in enhanced mortar ductility and increased failure strain and also reduction in the cost of mortar and its detrimental environmental impacts.