Tensile Bond Strength of Polymer Modified Mortar

This paper describes an investigation of improving the bond strength of masonry mortars through the use of polymer additives, so that more efficient use of unreinforced masonry may be realized. A brief description of the mechanisms involved in polymer-modification of cementitious materials is provided as background for the experimental program. Results from a clay brick, type S cement-lime masonry mortar bond strength testing program investigating various admixtures are presented. The admixture treatments include numerous latexes, a defoaming agent, and a superplasticizer. Test specimens were cured under both moist and dry conditions. Very significant increases in bond strength were realized through the addition of several polymers, a plasticizer, and combinations of polymers and the plasticizer.