Evaluation of Fresh Adhesive Mortars Through Various Rheological and Imaging Techniques

Abstract

Adhesive mortars are meant to glue tiles and during application they are applied with a toothed comb to ensure that the proper amount of material is distributed over the substrate, also to ease the later tile placement. Throughout the application, different types of strains and stresses are imposed to adhesive mortars, and one method is not enough to fully characterize their behavior. Thus, in this investigation various techniques were used to evaluate the mortar’s fresh properties. Bulk and interfacial oscillatory rheology combined with MRI characterizations were used to understand the rheological properties evolution and skin formation over time simulating the waiting period until the tile is emplaced. Squeeze flow measurements at different waiting times were used to indicate mortars behavior during tile placement and were complemented with small depth-of-field optical microscopy technique to obtain the visualization of the contact between mortar and tiles. The experimental variable studied was the content of cellulose ether – widely used admixture in adhesive formulations as viscosity and water retaining enhancer – and the applied methodology was able to assess the effects of the admixture by covering a wide range of the required fresh properties of adhesive mortars.