Due to its own hydration characteristics and physical structure, gypsum is a very good building material and is often widely used in domestic and foreign decoration markets. However, since gypsum sets and hardens very quickly, the working time is usually 3 to 30 minutes, which is easy to limit the use of gypsum. Therefore, it is particularly important to add gypsum retarder.
While the retarder changes the retarding time of gypsum, it also greatly damages the strength.
Advantages of gypsum retarder:
Adding less amount, longer retarding time
Higher hardness after coagulation, non-toxic, tasteless and more environmentally friendly
1. First mix construction gypsum powder with retarder, Yuhe hydroxypropyl methylcellulose or other additives evenly, then add sand, heavy calcium, etc., add sand or heavy calcium and stir for 15 minutes before releasing. (Note: Due to the different specific gravity of the materials, there will be stratification after long-term stirring, which will affect the product quality.)
2. For other products, such as mold gypsum and retarded gel water, you can put the retarder into the water first, and then add it to use after dissolving.
Practical formulations of gypsum products
Stucco plaster lower level:
Pure gypsum powder 300 kg
700 kg fine river sand
Hydroxypropyl methylcellulose 0.5-0.7 kg
Gypsum retarder 0.8-1 kg
Adhesive plaster (slow drying type):
Pure gypsum powder 800 kg
Heavy calcium powder 200 kg
Hydroxypropyl methylcellulose 2.5 kg
Retarder 2.5 kg
Paint plaster finish (gypsum putty):
Pure gypsum powder 500-700 kg
Heavy calcium powder 300-500 kg
Hydroxypropyl methylcellulose 2-2.5 kg
Gypsum retarder 1.5-2.1 kg
caulk plaster:
700 kg of pure gypsum powder
Heavy calcium powder 300 kg
Hydroxypropyl Cellulose 2.5kg
Dispersible latex powder 2kg
Gypsum retarder 2 kg