Hydroxypropyl methylcellulose HPMC is the main admixture of gypsum mortar, which has the functions of water retention and thickening, improving the adhesion between the mortar and the wall and improving the construction performance of the mortar.
According to the amount of desulfurized gypsum being 50% of the total mass and the amount of vitrified microbeads being 3.0% of the total mass, adjust the amount of gypsum retarder to keep the initial setting time of sprayed gypsum mortar at (100±20) min.
With the increase of the content of hydroxypropyl methylcellulose, the water retention rate of sprayed gypsum mortar gradually increased. When the content of hydroxypropyl methylcellulose ether was 0.20%, the water retention rate of the mortar reached 90%. Considering the actual use conditions of sprayed gypsum mortar, the tensile bond strength of sprayed gypsum mortar with concrete slabs and aerated concrete blocks was tested respectively. When the content of hydroxypropyl methyl cellulose ether reaches more than 0.15%, the tensile bond strength with the concrete slab is higher, and the change of the tensile bond strength is small with the increase of the content of cellulose ether; Concrete blocks have high water absorption, and the content of cellulose ether needs to reach more than 0.20% in order to achieve the effect that the tensile bond strength changes less with the increase of the content of cellulose ether. Considering that with the increase of the content of cellulose ether, the water consumption of mortar increases, and the flexural and compressive strength decreases, so the content of cellulose ether is determined to be 0.20%.
With anti-sag performance and pumping performance;
High water retention, improve the water retention performance of gypsum mortar products;
Reduce the phenomenon of hollow drum cracking;
Scratch performance is smooth;
Improve constructability, save time and reduce costs;
Sticky but not sticky, smooth stripping, suitable for machine spraying;
Improve gypsum product performance.
Application of hydroxypropyl methylcellulose gypsum series gypsum cellulose in machine-sprayed gypsum mortar:
1. Excellent water retention;
2. Good workability, sticky but not sticky, and smooth stripping.
3. Low initial viscosity and good fluidity;
4. Reduce the apparent viscosity of gypsum;
5. Reduce drying and cracking;
6. Increase pumpability and reduce labor intensity;
7. Good anti-sag performance;