In-situ methods to evaluate the flexural strength of polymer-modified mortars and mortar/concrete adhesion

Nowadays, due to the fact that concrete and mortar are considered as one of the most widely used materials in construction, so the use of in-site tests to determine their flexural strength and adhesion between mortar and concrete substrate is inevitable and is increasing. There are several methods for evaluating the flexural and bond strength of cementitious materials on site. In this paper, the flexural and bond strength of polymer modified mortar (PMM), using the "Twist off" semi destructive test has been evaluated. The styrene butadiene rubber (SBR) Latex has been used in mortars, which is added to mortars with 10, 15, and 20% ratios of cementitious materials. The correlation between experimental and “twist off” semi destructive test using linear and power regression analysis was determined, and the calibration curves were presented. Calibration curves can be used to convert the results of the "Friction transfer" test to the compressive strength of PMM. The results show the positive effect of polymer on the mechanical properties of repair mortars.

Keywords:

Twist off , Flexural strength , adhesion , PMM.