From Realtà Mapei International n° 71 - 21/11/2018
For example purposes, let’s choose three (excellent) materials: Carrara Marble, Red Verona Marble and Luserna Stone. But are they all really types of marble? Can I use the same bonding method for all three of them? How do they behave in damp conditions? These are all pretty basic questions but, as any stone installer knows only too well, apart from their commercial names, they are not the same at all. Their behavior in terms of compressive strength, abrasion resistance, water absorption and workability, for example, can vary quite considerably. And it is no mere coincidence that the reference norms divide stone materials into different families: marble, granite, travertine and natural stone (which includes everything not covered by the other definitions). Let’s look at each of the following three aspects separately: water absorption, dimensional stability and choosing the right installation system.
ARE STONE MATERIALS USED FOR FLOOR AND WALL COVERINGS IN THE RESIDENTIAL BUILDING SECTOR SENSITIVE TO CONTACT WITH WATER?
Some of them, yes. The presence of moisture underneath a marble floor, for example, can cause unsightly marks or stains in various colours to appear on the surface, such as yellow or red (which are often irreversible). In certain cases, the backs of slabs absorb so much water that a stone element can become permanently deformed. Where does the water underneath a floor covering come from? From a substrate that has not been dried correctly, for example, or if there is not an adequate vapour barrier to counteract rising damp. In certain particular cases, stone material may also absorb water contained in the adhesive itself.