The main cementing material of gypsum-based self-leveling mortar is gypsum, and it has the performance of automatic leveling. The ground leveled with it is accurate in size and extremely level. Gypsum itself has the property of micro-expansion. Using it as the basic material for self-leveling can make the leveled ground stable and greatly reduce the risk of cracking. At the same time, gypsum-based self-leveling mortar is constructed by pumping, which is very efficient. After leveling is completed, the strength can reach more than 90% of the design strength one day, and the decorative surface construction can be carried out in 1 to 2 days. A variety of floor materials can be laid on self-leveling mortar, including wooden floors, PVC plastic floors, floor paints, various tiles, marble, etc., but it is also reminded here that tile laying cannot be carried out directly.
Gypsum-based self-leveling mortar can harden in a short time, and people can walk on it 4-6 hours after the mortar is poured. However, a thin layer of mortar will form on the surface during the hardening process. This layer is too weak to be used for tiling and also slows down the drying time of the mortar. When cement-based adhesive is applied directly to the floor, the cement in the tile adhesive reacts with the gypsum in the self-leveling mortar to form a mineral called calcium sulfonate at the interface. The related structural changes are enough to completely separate the cementitious adhesive from the flattened base.
Therefore, before laying tiles on gypsum-based self-leveling mortar, necessary preparation measures should be taken to seal the porous surface of the gypsum base to prevent moisture from being absorbed from the tile adhesive, and to avoid the adverse reactions that often occur between cement-based mortar and gypsum substrates. Specifically, a primer can be sprayed between the gypsum self-leveling mortar and the tile to seal and isolate it. It can be a hydrophobic emulsion or a reactive resin to avoid problems such as poor adhesion caused by direct laying.
Gypsum-based self-leveling mortar is used for ground leveling layer, which has advantages that other materials cannot match. With the promotion of residential finished products, building floor heating backfill, and ground raising applications are becoming more and more common. The raising and leveling construction can be completed at one time with self-leveling mortar, and the use of floor heating backfill can also make the floor heating have better insulation and energy-saving effects during the application period. However, as we said before, a variety of floor materials can be laid on self-leveling mortar, but when laying ceramic tiles, primer spraying and sealing isolation measures should be carried out to achieve a good floor laying effect.