Preventing hollowing and cracking of premixed mortar(Ⅱ)
Preventing hollowing and cracking of premixed mortar(Ⅲ)

1.Watering, cleaning and repairing the wall before plastering

The traditional method of plastering mortar is to water and clean the wall to be plastered the next day before leaving get off work the day before. The wall must be repaired. However, some construction operations do not water, clean or repair the wall the day before. This can easily cause hollowing and cracking of the wall.

Because the mortar will interrupt the hydration reaction when it lacks water. It will affect the strength and adhesion of the mortar. If the wall is not cleaned or repaired, the mortar layer and the base layer will be isolated. And the adhesion will be greatly reduced. Or some places are large and some places are small. In this way, the plaster layer will crack, even fall off, and hollow due to too little or unbalanced restraint.

2.The thickness of plastering should be appropriate

If the one-time plastering is too thick or the degree of dryness is not well controlled. It is very easy to cause construction hollowing and cracking and shrinkage hollowing and cracking. Construction hollowing is caused by insufficient roughness of the interface agent and the loosening of the mortar layer by workers before the mortar absorbs water. As a result, the mortar layer and the interface agent peel off.

Shrinkage hollowing is caused by the bond strength of the interface agent being lower than the shrinkage stress caused by the inconsistency of the shrinkage rates of the mortar and the base layer. As a result, the interface agent and the base layer peel off. When plastering in layers, if the time interval between the two processes is too short, the second layer of mortar is applied before the primer mortar has finally set. Although it is applied twice in form, it is actually applied once, and cracks may occur due to various reasons such as plastic shrinkage.