What are the effects of hydroxypropyl methylcellulose on cement-based building materials mortar?
Hydroxypropyl methylcellulose products for construction are widely used to improve the performance of hydraulic building materials, such as cement and gypsum. In cement-based mortars, it can improve water retention, extend correction time and open time, and reduce sagging.
1. Improve construction
The application of hydroxypropyl methylcellulose HPMC can improve the workability of mortar.
2. Air bubble content
High air bubble content results in better mortar yield and workability, reducing crack formation. It also reduces the intensity value, giving the appearance of “liquification”. The air bubble content usually depends on the stirring time.
A good sag-resistant mortar means that there is no sag or slump damage when working in thick layers. Sag resistance can be improved by hydroxypropyl methylcellulose for construction. In particular, the newly developed construction-specific hydroxypropyl methyl cellulose can provide better sag resistance for mortar.
4. Lubrication ability
All air-entraining agents act as wetting agents by reducing the apparent tension and helping to disperse the fines in the mortar when mixed with water.
5. Water retention
The special hydroxypropyl methyl cellulose for construction avoids the penetration of water into the wall. An appropriate amount of water stays in the mortar, so that the cement has a longer time for hydration. The water retention is proportional to the viscosity of the cellulose ether solution in the mortar. The higher the viscosity, the better the water retention. Once the water molecules progress, the water retention decreases. As for the same amount of hydroxypropyl methylcellulose solution for construction, an increase in the amount of water means a decrease in viscosity. The improvement in water retention will result in an extension of the curing time of the applied mortar.