Plastering plaster will be the mainstream of interior wall plastering in the future
The plastering gypsum used for interior walls has the characteristics of light weight, moisture absorption, sound insulation, and strong living comfort. Gypsum plastering materials will become the mainstream of interior wall plastering in the future.
The hemihydrate gypsum used for interior wall plastering today is generally β-hemihydrate gypsum, and hemihydrate desulfurized gypsum, or natural gypsum, or phosphogypsum that meets environmental protection requirements is commonly used. The strength of the gypsum body varies from 2.5 MPa to 10 MPa. The quality of hemihydrate gypsum produced by gypsum manufacturers is very different due to the difference in raw material origin and process.
Formula Design of Plastering Gypsum for Engineering
The plastering gypsum used in engineering is usually heavy and sandy plastering gypsum. Due to the large construction area, the leveling thickness is more than 1 cm. Workers require fast leveling, so the gypsum is required to have good thixotropy. Good scraping, light hand feeling, easy to be exposed to light and so on.
analyze:
1. Good leveling performance. The gradation of sand is better, use medium sand with fine sand.
2. Good thixotropy. It is required that the filling property of the material is better. Can find thick, also can find thin.
3. No loss of strength. Use amino acid retarder, such as Italian Plast Retard PE.
Suggested formula for engineering plastering gypsum:
β-hemihydrate desulfurized gypsum: 250 kg (the strength of gypsum is about 3 MPa)
150-200 mesh heavy calcium: 100 kg (heavy calcium is not easy to be too fine)
1.18-0.6mm sand: 400 kg (14 mesh-30 mesh)
0.6-0.075mm sand: 250 kg (30 mesh-200 mesh)
HPMC-40,000: 1.5 kg (It is recommended to wash HPMC three times, pure product, less gypsum blooming, low viscosity, good hand feeling, and small air-entraining volume).
Rheological agent YQ-191/192: 0.5 kg (anti-sag, increase filling, light hand feeling, good finish).
Plast Retard PE: 0.1 kg (dosage is not fixed, adjusted according to coagulation time, protein, no strength loss).
Raw material example:
1.18-0.6 mm sand
0.6-0.075mm sand
β hemihydrate desulfurized gypsum (about 200 mesh)
The characteristics of this formula are: good construction, fast strength. Easy to level, relatively low cost, good stability, not easy to crack. Suitable for engineering.
Talking from experience
1. The gypsum returned from each batch should be inspected with the production formula to ensure that the setting time has not changed or is within the controllable range. Otherwise, the setting time is too long and it is easy to crack. If the time is too short, the construction time is not enough. Generally, the initial setting time of the design is 60 minutes, and the final setting time of gypsum is relatively close to the initial setting time.
2. The mud content of the sand should not be too large, and the mud content should be controlled at 3%. Too much mud content is easy to crack.
3. HPMC, low viscosity, high quality is recommended. The HPMC washed three times has low salt content, and the gypsum mortar has less frost. This surface hardness and strength are OK
4. When mixing dry powder, the mixing time should not be too long. After all the ingredients are fed, stir for 2 minutes. For dry powder, the longer the mixing time, the better. After a long time, the retarder will also be lost. It is a matter of experience.
5. Sampling inspection of products. It is recommended to sample and inspect the finished products from the beginning, middle and end of each pot. In this way, you will find that the setting time is different, and the retarder should be adjusted appropriately according to the needs.
Post time: Jan-18-2023