Influence of thickening agents on the adhesive and rheological properties of mortars

摘要

This paper presents an experimental study of adhesive and rheological properties of cement mortars proportioned with various contents of organic or mineral thickeners. Starting from a reference mortar formulation, we have investigated the effect of varying contents of a water-soluble polymer admixture and a bentonite-clay additive. To determine the adhesive properties the probe tack test was used. The tack test results have been exploited to identify the adhesion strength, the cohesion strength and the support’ adherence force. It is found that the cohesion component monotonically increases with bentonite content, while it displays a minimum when varying the polymer content. The behavior of the adherence force is more complex for both types of thickeners. In both cases, the evolution of the adhesive force versus thickener content displays optima depending upon the tack velocity. The rheological behavior of the mortars was also considered. By comparing the adhesive and the rheological properties, tack tests and rheological measurements appeared as complementary methods of characterization of mortars in the fresh state.