Redispersible latex powder is a commonly used organic gelling material. It is a powder obtained by spray drying a polymer emulsion with polyvinyl alcohol as a protective colloid. This powder can be uniformly dispersed in water after being put into water, forming an emulsion. Adding redispersible latex powder can improve the water retention of fresh cement mortar, as well as the bonding performance, flexibility, impermeability, and corrosion resistance of hardened cement mortar. 

Redispersible latex powder

The influence of redispersible polymer powder on the bond strength of cement-based materials

Emulsion and redispersible polymer powder can form high tensile strength and bonding strength on different materials after film formation. They are used as the second binder in the mortar to bond with the inorganic binder cement, cement and polymer respectively performs well to the corresponding specialties, so that the performance of the mortar can be improved. Through the observation of the microstructure of the polymer-cement composite material, it is believed that the addition of redispersible latex powder can make the polymer film and become a part of the pore wall. The internal force makes the mortar form a whole, which improves the internal content of the mortar. Poly strength, thereby increasing the failure stress of the mortar and increasing the ultimate strain. The long-term performance of the redispersible latex powder in the mortar was studied. It was observed by SEM that after 10 years, the microstructure of the polymer in the mortar remained unchanged, maintaining stable bonding, bending resistance and compression resistance. Strength and good water repellency. Wang Ziming et experts studied the formation mechanism of the strength of the tile adhesive with redispersible latex powder and found that after the polymer is dried to form a film, the polymer film forms a flexible connection between the mortar and the tile on the one hand, and the other hand, the polymer in the freshly mixed mortar increases the air content of the mortar and affects the surface formation and wettability. During the subsequent setting process, the polymer will also affect the hydration process and shrinkage of the cement in the binder. Better influence, all of which will have better help to improve the bond strength.

dry mix mortar

Adding redispersible latex powder to the mortar can significantly improve bonding strength with other materials. The reason is that the hydrophilic latex powder and the liquid phase of the cement suspension penetrate into the pores and capillaries of the matrix together, and the latex powder is in the pores and capillaries. The inner film is formed and firmly adsorbed on the surface of the substrate, thereby ensuring a good bonding strength between the cementing material and the substrate.

waterproof mortar

The optimization of the working performance of the latex powder on the mortar is due to the fact that latex powder is a polymer with polar groups. When the latex powder is mixed with EPS particles, the non-polar segments in the polymer main chain of the latex powder will physically adsorb on the non-polar surface of EPS. The polar groups in the polymer are oriented outwards on the surface of the EPS particles, which makes the EPS particles change from hydrophobic to hydrophilic. Due to the modification effect of latex powder on the surface of the EPS particles, it solves the problem that EPS particles are easily exposed to water, floating, and the problem of mortar delamination. At this time, mixing with cement, the polar groups adsorbed on the surface of the EPS particles interact with the cement particles and are closely combined, so that the workability of the EPS insulation mortar is significantly improved. This is manifested in that the EPS particles are easily wetted by the cement paste, and the bonding force between the two is greatly improved.

Redispersible powders

Post time: Dec-15-2021