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Effect of Redispersible Emulsion Powder on Properties of Cement Mortar

The redispersible emulsion powder has good redispersibility, redisperses into an emulsion upon contact with water, and its chemical properties are almost identical to the original emulsion. Adding dispersible emulsion powder to cement or gypsum-based dry powder ready-mixed mortar can improve various properties of mortar, such as: improving the bonding force and cohesion of the material; reducing the water absorption of the material and the elastic modulus of the material; enhancing the flexural strength, impact resistance, wear resistance and durability of the material; improving the construction performance of the material.

Mechanical properties and water resistance

Mixing latex powder in cement mortar will form a highly flexible and highly elastic polymer mesh membrane, thus significantly improving the performance of mortar, especially the tensile strength of mortar is greatly improved. When the external force is applied, due to the improvement of the overall cohesion of the mortar and the soft elasticity of the polymer, the occurrence of microcracks will be offset or slowed down. Through the influence of the content of rubber powder on the strength of thermal insulation mortar, it is found that the tensile bond strength of thermal insulation mortar increases with the increase of the content of latex powder, and the flexural strength and compressive strength decrease to a certain extent with the increase of the content of latex powder, but it can still meet the requirements of the exterior surface of the wall.
For cement mortar mixed with latex powder, the bond strength of 28d increases with the increase of latex powder content. With the increase of the content of latex powder, the bonding ability of cement mortar and old cement concrete surface is improved, which ensures its unique advantages for repairing cement concrete pavement and other structures. And the compression ratio of the mortar increases with the increase of the amount of latex powder, and the flexibility of the surface mortar increases. At the same time, it is also found that with the increase of latex powder content, the elastic modulus of mortar decreases first and then increases. On the whole, with the increase of poly-ash ratio, the elastic modulus and deformation modulus of mortar are lower than those of ordinary mortar.
The effect of the amount of latex powder on the bending strength of geopolymer mortar is very obvious. The flexural strength of fly ash-metakaolin geopolymer mortar can be increased by 1.8,1.9 and 2.9 times respectively when the dosage of latex powder is 3%,6% and 10%. The ability of fly ash-metakaolin geopolymer mortar to resist deformation increases with the increase of latex powder content. The flexural toughness of fly ash-metakaolin geopolymer increased by 0.6,1.5 and 2.2 times when the content of latex powder was 3%,6% and 10%, respectively.
SAE emulsion powder significantly improves the flexural and bond tensile strength of cement mortar, thus improving the flexibility of cement mortar and improving the bond tensile strength of cement mortar-concrete and cement mortar-EPS board system.
When the poly-ash ratio is between 0.3 and 0.4, the fracture elongation of polymer modified cement mortar jumps from less than 0.5% to nearly 20%, thus making the material change from rigid to flexible, and further increasing the content of polymer can obtain more excellent flexibility.
Increasing the amount of latex powder in mortar can improve the flexibility. When the content of polymer is about 15%, the flexibility of mortar has changed significantly, and when the content is higher than this, the flexibility of mortar increases with the increase of the content of latex powder.
Through the bridge crack ability and lateral deformation test, it is found that with the increase of latex powder content (from 10% to 16%), the flexibility of mortar gradually increases, the dynamic bridge crack ability (7d) increases from 0.19mm to 0.67mm, while the lateral deformation (28d) increases from 2.5mm to 6.3mm. At the same time, it is also found that the increase of the content of latex powder can slightly improve the impermeability pressure of the back surface of the mortar, and can reduce the water absorption of the mortar. With the increase of latex powder content, the long-term water resistance of mortar decreased gradually. When the dosage of latex powder is adjusted to 10%-16%, the modified cement-based slurry can obtain good flexibility and excellent long-term water resistance.