At present, it is about to enter summer, and the temperature is relatively high, especially in the northern region. The temperature is high and the air is dry. The surface temperature of the wall can reach 60°C. Due to the temperature, the cellulose often has problems such as poor construction and powder removal during construction. The main reason is that due to the high temperature of the wall, the water retention of the putty is not good, so the water in the putty is quickly absorbed or evaporated by the wall, so that the putty cannot be repeatedly coated and scratched. Hollowing and peeling appear. How to improve the water retention of powdery exterior wall putty mainly has the following methods:
1. Increase the amount of cellulose ether
Cellulose ether has good water retention, but the water retention performance does not increase after a certain amount of cellulose ether is added. At the same time, the increase in cellulose increases the viscosity of the putty and the construction is not smooth. In addition, the cost of the putty increases.
2. Increase the amount of lignocellulose
Lignocellulose has a certain water retention effect. The addition of wood fiber improves the water retention capacity of the material, makes the material system hydrated evenly, and can improve the workability at the same time, but the water retention principle of lignocellulose is different from that of cellulose. It has the characteristic of hair absorption. (Water conduction), there will be moisture between each fiber, and when the moisture in the surrounding environment of the fiber changes and decreases, the moisture between the fibers will be released evenly. Open time, not easy to crack. However, because the thickness of the putty on the exterior wall is very thin, the thickness of each scrape coating is only 0.5-1mm. When the surface temperature of the base layer and the air temperature are relatively high, its water retention performance is not obvious, and the repeated scrape coating performance is average.
3. Increase the amount of polymer
On walls with thinner putty, dry air and high base temperature, increasing the amount of polymer is one of the better ways to make the putty have repeated scraping properties, but the price of redispersible latex powder is relatively high , a large amount will greatly increase the cost of putty. It can also play a better role by adding a small amount of polyvinyl alcohol powder, but the viscosity of polyvinyl alcohol powder is relatively large, which will affect the workability, and the sanding property of the putty is not good. .
4. Add polymer lubricant
Through the test, it is considered that it is a better choice to add a high-volume lubricant to the exterior wall putty in the environment of high temperature in summer. The lubricant belongs to the polymer compound, and the rheological lubricant is mainly aimed at improving the construction performance in the cement-based system. Open time and consistent performance. Increases the workability and sag resistance of mortars, plasters, renders, plasters and adhesives and prevents delamination of self-leveling cement. The reason for water retention is that there are a large number of hydrophilic functional groups on its molecular chain. In the case of repeated scraping and coating, it will not lose water, has outstanding water retention performance, and has thickening and thixotropy at the same time, making the construction smoother and can partially replace cellulose, but its price is only cellulose ether, and its dosage is 0.1-0.2%. , is a very cost-effective material, if used together with cellulose ether, lignocellulose, and redispersible latex powder, the effect will be better.