In premixed spraying mortar, the addition of hydroxypropyl methylcellulose ether is very low, but it can significantly improve the performance of wet mortar. It is a main additive affecting the construction performance of mortar. Reasonable selection of cellulose ether with different varieties, different viscosities, different particle sizes, different viscosity and addition amount has a positive impact on the improvement of the performance of dry powder mortar. At present, many masonry and plastering mortars have poor water retention performance, and water slurry separation will occur after standing for a few minutes. Water retention is an important performance of methyl cellulose ether, and it is also the performance concerned by many domestic dry powder mortar manufacturers, especially those in areas with high temperature in the south. The factors affecting the water retention effect of dry powder mortar include the addition amount of MC, MC viscosity, particle fineness and the temperature of service environment. Cellulose ether is a synthetic polymer made from natural cellulose by chemical modification.
The important role of water-soluble cellulose ether in mortar mainly has three aspects: first, excellent water holding capacity, second, the influence on mortar consistency and thixotropy, and third, the interaction with cement. The water retaining effect of cellulose ether depends on the water absorption of base course, the composition of mortar, the layer thickness of mortar, the water demand of mortar and the setting time of setting material. The water retention of cellulose ether itself comes from the solubility and dehydration of cellulose ether itself.
Hydroxypropyl methylcellulose ether plays a role in water retention, thickening, delaying cement hydration power and improving construction performance in premixed spraying mortar. Good water holding capacity can make the cement hydration more complete, improve the wet viscosity of wet mortar, improve the bonding strength of mortar, and adjust the time. Adding hydroxypropyl methylcellulose ether into mechanical spraying mortar can improve the spraying or pumping performance and structural strength of mortar. Therefore, cellulose ether is widely used in ready mixed mortar as an important additive.