1、 Cracking after drying
After the plastering mortar dries, some surfaces may experience cracking or hollowing. The following aspects can be considered:
1. The gypsum used was burnt too much, resulting in high levels of the three anhydrous components;
2. During the construction process, due to excessive ventilation, the mortar is made too thin, and its water retention capacity is insufficient, which can also lead to cracking of the mortar during the plastic deformation process.
Recommended solution:
1. If the gypsum used is burnt, you can try to solve it through the following methods:
(1) Store the current gypsum powder for a period of time to reduce the content of the three anhydrous components;
(2) Select appropriate gypsum powder for formula design;
(3) Under the premise of using the gypsum powder, appropriate alkaline activators can be added to the formula;
2. The plastering gypsum can be made to an appropriate thickness through construction techniques. If the construction party needs to make it thinner, it is recommended to add sufficient cellulose ether in the formula design to ensure the water retention of the mortar.
2、 Powder loss after hardening
After the plaster is dried, there are problems with low surface strength and powdering on the surface. The following aspects can be considered:
1. The addition amount of inorganic/organic cementitious materials is insufficient, or their own strength that can be improved is not enough;
2. Perhaps the insufficient water retention capacity of the mortar leads to low strength and susceptibility to powdering;
3. When the slow setting time of gypsum mortar is too long, it can also cause the mortar to lose powder due to slow drying.
Recommended solution:
1. If it is related to the cementitious material, it is recommended to increase its addition amount or replace it with a suitable cementitious material;
2. When the water retention capacity of mortar is found to be insufficient, it is recommended to increase the amount of cellulose ether added or replace it with a suitable cellulose ether;
3. If it is found that the setting time of plastering gypsum is too long, it is recommended to reduce the amount of gypsum retarder added or replace it with a suitable retarder/gypsum powder.
3、 Color Hair Flower
Due to the long time from initial setting to final setting, or inconsistent thickness of scraping, the drying time of mortar in different places is not consistent, which can easily lead to color fading problems; Alternatively, after construction and before the strength of the mortar reaches a certain level, encountering rainy weather can also easily lead to color fading.
Recommended solution:
1. The plastering gypsum can be uniformly and appropriately thick through construction techniques;
2. If the initial to final setting time is too long, it is recommended to reduce the amount of retarder added or replace it with a suitable retarder/gypsum powder;
3. We need to avoid construction in rainy weather and reduce the occurrence of color bleeding.
4、 Roll leather during construction
1. If there is a rolling phenomenon during the first construction of plastering gypsum, it is generally caused by excessive dust on the base layer;
2. If the plastering gypsum rolls during the second layer of wall construction, it is generally due to insufficient water retention capacity, resulting in the mortar strength of the first layer not meeting the requirements of the second layer of construction.
Recommended solution:
1. If there is too much dust on the base layer during the first construction, it is recommended to clean the base layer in advance.
2. If there are problems during the second construction, it is recommended to increase the amount of cellulose ether added in the formula or replace it with a suitable cellulose ether.
5、 Mortar flow hanging
During the plastering and mortar construction, the phenomenon of sagging occurred, which can be analyzed from the following aspects:
1. It is possible that the anti sagging additives are not sufficient;
2. From the perspective of construction technology, it may be due to the thickness of the mortar being too thick.
Recommended solution:
1. Replace or add appropriate anti sagging additives, such as starch ether, thixotropic lubricants, etc., or use functional cellulose ether;
2. The plastering gypsum can be uniformly and appropriately thick through construction techniques.
6、 Fast hardening speed in the bucket
When plastering gypsum is being mixed during construction, it is found that its slow setting time in the bucket is getting shorter and shorter, which is not conducive to construction. This is because the residual mortar components in the previous bucket combined with water to form dihydrate gypsum, which has a setting promoting effect. As the amount of dihydrate gypsum remaining in the bucket increases, the speed at which the newly poured mortar hardens in the bucket becomes faster and faster.
Recommended solution:
After mixing the plastering gypsum several times on the wall, remember to clean the mixing bucket regularly and multiple times to reduce the content of dihydrate gypsum.
7、 Surface blistering
When plastering gypsum is used for wall construction, the surface gradually develops bulges and bubbles, which can be considered from the following aspects:
1. The shear wall has not been fully enclosed, resulting in bubbles in the plaster on the upper wall;
2. Perhaps due to the fine filling material in the plaster gypsum, the density of the mortar is too high, which can penetrate into the gaps of the wall and squeeze out bubbles, resulting in foaming;
3. It is possible that high viscosity cellulose ether or high molecular weight organic compounds were used, which caused the mortar to easily bubble.
Recommended solution:
1. Suggest using interface agents to seal the shear walls horizontally and vertically;
2. If it is caused by the filling material of plastering gypsum being too fine, it is recommended to readjust the formula and choose a suitable aggregate mix scheme;
3. Replace cellulose ether with appropriate viscosity and suitable additives.
