What is meant by the term single grain mortar and why should this be used in combination with natural stone coverings?
The customary cement screeds are made from various grain fractions. As these include very fine granulations, these screeds are very dense in texture and any penetrating water is held for a relatively long time within the screed. Natural stone coverings absorb water, leading to among other things the formation of damp stains. It is therefore necessary to guide the water out of the structure as quickly as possible. This is done by using single grain mortars that contain a high proportion of cavities and therefore allow the water to drain more quickly from the screed. Single grain mortars are made from only one grain fraction (e.g. gravel with granulation of 2-8mm, or chippings with a granulation of 3-5mm) with the addition of trass cement and water. There are also “dry mortars” by several manufacturers on the market.
