Ash calcium powder, heavy calcium powder (or gypsum powder), and cellulose are the main substances that make up putty powder.
The function of ash calcium powder in putty is to improve the function of the product, including improving the strength, hardness, water resistance of the putty powder product, and the performance of scraping and grinding during construction. Heavy calcium powder is used as a filler to reduce production costs, and cellulose plays a role in water retention. , bonding and other functions.
In the construction of putty powder, foaming is a relatively common problem. What causes it?
Ash calcium powder (the main component is calcium hydroxide, which is a refined product of lime), heavy calcium powder (the main component is calcium carbonate, which is calcium carbonate stone powder directly ground from calcium carbonate stone) generally will not cause putty powder to crack after use. bubble phenomenon.
cause of blistering
The main reasons for the foaming of putty powder are as follows:
1. The base layer is too rough with small holes. When scraping, the putty compresses the air in the hole, and then the air pressure rebounds to form air bubbles.
2. The single-pass scraping is too thick, and the air in the pores of the putty is not squeezed out.
3. The base layer is too dry and the water absorption rate is too high, which will easily cause more air bubbles in the surface layer putty.
4. Water-resistant paint, high-grade concrete and other base surfaces with good airtightness will cause blistering.
5. Putty is prone to bubbles during high temperature construction.
6. The water absorption of the base material is too low, which leads to the relative water retention time of the putty is too long when scraped, so that the putty stays in the state of slurry on the wall for a long time and does not dry, so that the air bubbles are not easy to be squeezed out by the trowel, resulting in pinholes Pores are the reason why there are more air bubbles on the top of the scraped formwork than on the wall in engineering. The water absorption of the wall is large, but the water absorption of the formwork top is extremely low.
7. The viscosity of cellulose is too high.
Post time: Apr-19-2023