Dimensional changes of adhesive mortars under tile

High shrinkage of tile adhesive is believed to be a technological flaw, leading to the risk of faulty tile fixing. As in real‐life conditions, there is a very limited possibility of mortar movement under tile, the shrinkage/expansion‐induced stress could be created, which needs to be absorbed by the mortar. The significance of the problem increases with the tile size. On contrary, the length changes of such materials are usually measured on the prisms which reflects neither the application thickness nor the real‐life curing conditions of the mortar.

In this paper, we are aiming to measure tile adhesives' length change potential in simulated real‐life conditions. The test set‐up involves a Thin‐Layer‐Shrinkage‐Measuring‐System allowing for the examination of flat rectangular samples of 350x350 mm in size and several millimeters of thickness. Dimensional changes were measured in situ by the laser sensors. Additionally, the weight changes were monitored over the whole measurement. The obtained results were juxtaposed with the shrinkage measured on the prisms.

The paper provides valuable insights into the dimensional changes of tile adhesives in real‐life applications. Obtained results challenge the conventional measurements done on prisms stored in ambient conditions.