Adhesive properties and interfacial rheology of adhesive mortars

Adhesive mortars consist basically of cement, sand, mineral fillers and a variety of additives (cellulose ethers, air-entraining, latex) and are used to glue ceramic tiles (and other pieces like stone, glass etc) to substrates.

They are usually applied in a large surface on the substrate in the form of ribs on which tiles are put. In order to obtain a good performance it is important that when the tile is installed, the mortar rheological properties allow for good contact between them, even after several minutes (open time) of exposure to ambient conditions either at internal or external building areas.

For this purpose, it is necessary to avoid the formation of a rigid and/or dry layer at the mortar-air interface, which may be difficult to be deformed or wet the tile surface properly.

Adhesive properties of mortar

As the initial contact between mortar and tile is the first step for the development of adhesive properties between the materials, a good comprehension of the rheological properties evolution at the air-mortar interface is of great importance for mortar producers and users.

In this context, this thesis firstly developed methods to evaluate interfacial properties and a microscopical technique to visualize the contact. Then, those techniques combined with already existent squeeze flow/tack test and rheological methods can be used to evaluate how polymer additives such as cellulose ether influence the adhesive mortar rheological properties in the volume and at interface to further understand the adhesive properties.

And finally, with the use of NMR, those properties could be correlated with water distribution evolution.