Comparison of in-situ methods to measuring adhesion of polymer modified mortar and concrete

There are several methods for measuring the bond strength between repair mortars and concrete substrates. But most methods are laboratory and cannot be used in situ. Therefore, in this paper, by using in situ tests, the shear and tensile bond strength between polymer modified mortar and concrete substrate has been measured. The methods used are “Twist off” and “Pull off”. The styrene-butadiene rubber Latex Polymer has been used in mortars, which is added to mortars with 10, 15, and 20% ratios of cementitious materials. Then, using regression analysis, the relationship between shear bond strength and tensile bond strength has been determined. And the correlation coefficient between the “Twist off” and “Pull off” results is presented. due to the high correlation between shear adhesion strength and tensile adhesion strength resulting from "Twist -off" and "Pull-off" tests, it is possible to use a simple and inexpensive "Twist-off" machine instead of using an expensive "Pull-off" machine.