1. Cause of hollowing:
1), when smoothing the layer, the structural layer does not have a wetting process, and the structural layer absorbs moisture from the mortar;
2), the water-cement ratio of the mortar does not meet the design requirements;
3), the mortar is unevenly mixed and the cement is not fully mature;
4), the effective maintenance is not carried out after the construction is completed;
5), the main reason for moisture! Before laying the floor, if plastic film is not well laid, it will easily bulge!
2. Solution:
1) For the corners of the room, and the hollow area is not greater than 0 or 1 square meter and there are no cracks, it can generally not be repaired;
2), places where people are frequently active, the hollow area is greater than 0 or 1 square meter or smaller, but there are obvious cracks, repair should be carried out. During partial renovation, the hollow part should be chiseled into a square or round shape. After cleaning, fill with a mixture of the same material as the surface layer. Cover and cure immediately after final solidification to prevent early shrinkage cracks; (3) Large area of hollows, the entire surface layer should be chiseled and the bottom surface should be chiseled, and a new surface layer should be repaved according to the process requirements.
