Study of Bond Strength between Polymer-Modified Mortars/Concrete and Their Mechanical Properties using “Friction-Transfer” and “Pull-off” Methods

Nowadays, polymers in cement-based mortars are frequently used to improve mechanical properties and increase the adhesion between the repair mortar and concrete substrate. In the present study, the mechanical properties of the polymer-modified mortars in the various ages were evaluated using the semi-destructive and in-situ “friction-transfer” and “pull-off” tests. For this purpose, the repair mortar was prepared with various styrene butadiene rubber (SBR) latex-cement ratios (10, 15, and 20%) and tested at 7, 42, and 90 days of age. The correlation between the results from semi-destructive tests and the compressive and flexural strengths of mortars were determined. The calibration diagrams were presented to determine the mechanical properties of the mortars. Also, the effect of the polymer was investigated on the shrinkage and bond strength between mortars and concrete substrate. Finally, the stress and cracks obtained from the “friction-transfer” and “pull-off” tests were presented using the finite element analysis software (ABAQUS). There was excellent congruence between the results from the above tests and the finite element analysis. There was a high correlation between the results of the “friction-transfer” and “pull-off” tests. Therefore, the simple and inexpensive “friction-transfer” device can be used instead of the expensive “pull-off” device. Besides, the significant correlation between the mechanical properties of the polymer-modified mortars and the above tests shows the suitability of the semi-destructive methods in investigating the mechanical properties of the mortars.