Effect of hydroxypropyl methylcellulose HPMC on cement-based building materials mortar
Construction-specific hydroxypropyl methylcellulose products are widely used to improve the performance of hydraulic building materials, such as cement and gypsum. In cement-based mortars, it improves water retention, extends correction and open times, and reduces sagging.
1. Water retention.
Construction-specific hydroxypropyl methylcellulose prevents moisture from penetrating into walls. An appropriate amount of water stays in the mortar, allowing the cement to hydrate longer. 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 increase, the water retention decreases. Because for the same amount of building-specific hydroxypropyl methylcellulose solution, an increase in water means a decrease in viscosity. Increased water retention will lead to a longer curing time of the mortar being constructed.
2. Improve workability.
The application of hydroxypropyl methylcellulose HPMC can improve the workability of mortar.
3. Lubricating ability.
All air-entraining agents act as wetting agents by reducing surface tension and helping the fine powder in the mortar to disperse when mixed with water.
4. anti-sag
A good anti-sag mortar means there is no danger of sagging or downward flow when applied in thick layers. The sag resistance can be improved by construction-specific hydroxypropyl methylcellulose. In particular, the newly developed construction-specific hydroxypropyl methylcellulose can provide mortar with better anti-sag properties.
5. bubble content
High bubble content results in better mortar yield and workability, reducing crack formation. It also reduces the strength value and causes a "liquefaction" phenomenon. The bubble content usually depends on the mixing time.
