The plastering mortar on the wall has low strength, insufficient marking, sand and powder loss, hollowing and cracking, and unevenness… Many people will find it very troublesome if the above situations occur!
However, if these phenomena are just superficial, they may not be as serious as you think. As long as there is nothing wrong with the main structure, these superficial problems are relatively easy to solve.
The sand and powder on the wall are peeling off, which is of course caused by the low strength of the plastering mortar and insufficient marking. The hollowing and cracking of the mortar layer on the wall may be caused by excessive cement dosage or excessive strength in the plastering mortar, especially cracking.
(Note: distinguish whether the wall mortar is cracking or the main wall is cracking? The main wall cracking is not included in this).

How to solve the problem of low strength of plastering mortar?

As mentioned above, low strength of wall plastering mortar will cause sand and powder to fall off the wall. The solution to this problem is simple. Just use sand to clean it. If the strength of the plastering mortar is low, use sand to clean it.

How to solve the problem of hollowing and cracking of the mortar layer on the wall?

Cause hollowing and cracking of the mortar layer. Exclude structural problems with the main wall. Mostly this is because the strength of the mortar is too high. That is, the amount of cement used is too large when mixing cement and sand. The higher the strength of the wall mortar, the more cracks and cracks will be more obvious.
Hollow mortar layer generally means that the bond between the base layer of the wall and the plastering mortar layer is not strong. Or delamination caused by insufficient density of plastering mortar.

Fix:

(1) Clean the floating sand and dust on the wall surface. Mix the sand-clean wall desanding repair solution evenly. Then spray it on the wall to make it fully moist and prevent it from running away. Plastered walls with moderate or severe desanding should be sprayed a second time after an interval of 30 minutes (an interval of 10-20 minutes if the suction material penetrates too fast, please refer to the on-site test). Check after 8 hours. If the effect is not achieved locally, analyze the reasons or perform a third spraying replenishment.
(2) For the desanding problem of the plaster layer caused by weathering over time, failure of the cement in the plaster mortar (or too low cement content) or excessive sand and soil content. This kind of situation will affect the “sand cleaning” effect. Such walls need to remove the old plaster layer and plaster it again.