What Effects Do Cellulose, Starch Ether And Redispersible Polymer Powder Have On Gypsum Mortar?

Hydroxypropyl Methyl Cellulose HPMC
1. It has stability for acid and alkali, and its aqueous solution is very stable in the pH=2 ~ 12 range. Caustic soda and lime water do not have much effect on its performance, but alkali can speed up its dissolution rate and slightly improve the viscosity.
2. HPMC is an efficient water-retaining agent for dry mortar system, which can reduce the rate of mortar secretion and stratification, improve the cohesiveness of mortar, effectively inhibit the formation of mortar plastic cracks, and reduce the mortar plastic cracking index.
3, it is a non-ionic and non-polymeric electrolyte, which is very stable in aqueous solutions of metal salts and organic electrolytes, and can be added to building materials for a long time to ensure that its durability is improved.
4, the working performance of the mortar has been significantly improved, the mortar seems to have "oiliness", can make the wall joint full, smooth surface, so that the mortar and the base bond firmly, and can extend the operation time.

Water retention
The realization of internal curing is conducive to the improvement of long-term strength, the inhibition of bleeding, the prevention of mortar settlement, the shrinkage and the improvement of mortar cracking resistance.

Prevent segregation, improve the uniformity of mortar, improve the wet bond strength, and improve the anti-hanging performance.

Air entraining
Improving mortar performance. With the higher the viscosity of cellulose, the longer the molecular chain, the more obvious the air entraining effect.

Delayed coagulation
Cooperate with water retention to extend the opening time of mortar

Hydroxypropyl Starch ether
1. The higher hydroxypropyl content in starch ether gives the system stable hydrophilicity, turning free water into bound water, which plays a good water retention role.
2. Starch ethers with different hydroxypropyl contents have different abilities to assist cellulose in retaining water at the same dosage.
3. The substitution of hydroxypropyl group increases the swelling degree in water and compresses the space for particle flow, thus achieving the effect of thickening and viscosity increasing.

Thixotropic lubricity
Starch ether is rapidly dispersed in the mortar system, changing the rheology of the mortar and giving it thixotropy. When external force is applied, the viscosity of the mortar will be reduced, ensuring good construction and pumpability, and giving it thixotropy. It has a smooth feel. When the external force is withdrawn, the viscosity increases, giving the mortar good resistance to sagging. Among putty powders, it has the advantages of improving the brightness of putty oil and polishing brightness.

Auxiliary water retention effect
Starch ether itself has hydrophilic properties due to the role of hydroxypropyl groups in the system. When combined with cellulose or added in a certain amount to the mortar, it can increase water retention to a certain extent and improve the surface drying time.

Anti-sag and anti-slip
Excellent anti-sag effect and shaping effect.


Redispersible polymer powder
1. Improve the workability of the mortar. Redispersible powder or RDP particles are dispersed in the system, giving the system good fluidity and improving the workability and workability of the mortar.
2. Improve the bonding strength of the mortar. After the rubber powder is dispersed into a film, the inorganic and organic matter in the mortar system can be fused together. It can be imagined that the cement and sand in the mortar are the bones, and the latex powder forms the ligaments. The cohesion increases, the strength increases, and a flexible structure is gradually formed.
3. Improve the weather resistance of the mortar. Freeze-thaw resistant latex powder is a thermoplastic resin with good flexibility, which can enable the mortar to respond to external changes in cold and heat, effectively preventing the mortar from cracking due to temperature changes.
4. Improve the flexural strength of mortar. The polymer and the cement slurry form complementary advantages. When cracks are caused by external forces, the polymer can span the cracks and inhibit the expansion of the cracks, thereby improving the fracture toughness and deformability of the mortar.

Post time: Mar-06-2024