Five quality problems of wet-mixed mortar and their solutions

01 Drying time of plastering mortar on the wall

The drying time of the upper wall is mainly related to the water absorption of the wall, the water retention of the mortar, the setting time of the mortar, and the environmental humidity

The wall humidity is normal and the air humidity is normal and the construction thickness is within 2cm

In this case, the drying time on the wall is normal, which is the same as the mortar mixed on site

The wall humidity is very high or the air humidity is very high or the construction thickness exceeds 2cm

In this case, the drying time of the mortar on the wall is one to three hours longer than that of the on-site mortar.

solution

First, it is recommended to pour water on the wall of the construction site one to two days in advance to increase the water-absorbing coating of the wall to the mortar

Second, it is recommended to spin the slurry in advance to a certain thickness to an elevation of about 1~2cm for the thick part of the construction, and it can be patched up at one time the next day

The third is to reduce the amount of additives to reduce the water retention of the mortar

The fourth is to shorten the opening time of the mortar and let the mortar quickly reach the setting time to shorten the drying time

The thickness of the mortar

Thickness question

If the mortar is too thick, the construction surface will be rough and difficult to polish
.
Too fine mortar will cause workers to wipe the wall too thinly at one time, which will affect the construction progress, and the surface hardness of the hardened mortar will also decrease
.

solution

Before production, you must go to the sand yard to judge the thickness of sand in advance, and control the sand fineness modulus at 2.
4~2.
7 as the best
.

03 The problem of stones in mortar

The appearance of large stones in the mortar will seriously affect the performance of the mortar
.

solution

1.
Strictly clean the sand in the machine

2.
Strengthen the work awareness of forklift drivers to avoid mixing stones when shoveling sand

3.
Make sure the inside of the mixer truck is cleaned

4.
Strict cleaning should be carried out on the upper sand warehouse and belt

5.
Try to avoid that the buckets of different materials are too close to each other, and make sure that the sand bucket wall is not perforated to ensure that there will be no mixing

6.
Regularly check the screen of the sand screening machine to avoid the quality fluctuation of the sand after damage

04 The problem of mortar hollowing

Construction hollowing

The roughness of the interface agent is insufficient or the plaster layer is loosened by rubbing before the mortar has not collected water, or the bonding strength of the mortar itself is insufficient, causing peeling between the mortar layer and the interface agent layer

Contractile hollowing

Irregular treatment of the base layer or the adhesion of the interface layer is lower than the shrinkage stress between the mortar and the interface layer, causing the interface agent layer and the base layer to peel off

solution

The bonding force between the ready-mixed mortar itself and the smooth shear wall is far from enough, so an interface agent must be used
.

The function of the interface agent is to increase the bonding force between the mortar and the shear wall, and to increase the contact area between the mortar and the wall, so as to evenly disperse the shrinkage stress between the mortar and the wall, and effectively avoid the shrinkage stress from being too concentrated on the wall.
A large area hollowing phenomenon that is stowed in a certain place
.

At present, the most commonly used method on the construction site is to add construction glue and cement to make the interface rough
.
However, there are still many quality accidents of mortar hollowing in a lot of projects because of the randomness of construction in this way
.

The use of air compressors and spray guns to spray hair is more and more common, and the use of I type concrete interface treatment agent produced by professional manufacturers has solved the problem of excessively wide napping or missing napping, because its construction is relatively easy and labor-saving.
It can be sprayed in place everywhere
.
The spray point is uniform and rough, and the adhesive force is strong, which can effectively disperse the shrinkage stress generated during the drying process of the mortar
.

05 Cracking on the wall of plastering mortar

solution

1.
Strictly control the sand rate greater than or equal to 78%

2.
Strictly control the mud content of sand not to exceed 3%

3.
Try to avoid the use of mortar tail slurry