Regarding the amount of redispersible latex powder in mortar, most customers are concerned about the following. A brief introduction: Redispersible latex powder can greatly improve the adhesion between mortar and base, but it will also reduce the water resistance of mortar. sex. The water repellent can effectively improve the ability of the mortar to resist micro-pressure water, but the water repellent may reduce the cohesiveness of the mortar. Therefore, when formulating ready-mixed mortar products, we should comprehensively consider the influence of each component on the performance indicators of the mortar, and determine the economical, reasonable and technologically advanced mortar formula through experiments. Redispersible latex powder can significantly improve the bond strength of mortar. Due to the high price of redispersible latex powder, the larger the dosage, the higher the cost of dry-mixed mortar, so it must be considered from the cost. High bond strength can inhibit shrinkage to a certain extent, and the stress generated by deformation is easy to disperse and release. Therefore, bond strength is very important to improve crack resistance.
The research shows that the synergistic effect of cellulose ether and rubber powder is beneficial to improve the bond strength of cement mortar. With the increase of the amount of dispersible polymer powder, the bond strength gradually increases. When the amount of latex powder was small, the bond strength increased significantly with the increase of the amount of latex powder. For example, when the amount of latex powder is 2%, the bonding strength reaches 0182MPa, which has met the national standard requirement of 0160MPa. Take putty powder as an example: adding latex powder can significantly improve the bonding strength of putty and substrate, because 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 penetrates into the pores and capillaries. A film is formed in the capillary and is firmly adsorbed on the surface of the substrate, thereby ensuring a good bond strength between the cementitious material and the substrate. When the putty was removed from the test plate, it was also found that the increase of the amount of latex powder did improve the adhesion of the putty to the substrate. But when the amount of latex powder exceeds 4%, the increasing trend of bond strength slows down. Not only dispersible latex powder, but also inorganic materials such as cement and heavy calcium carbonate contribute to the adhesive strength of putty, so the adhesive strength does not show a linear law with the increase of the amount of latex powder.
Water resistance and alkali resistance of putty are an important test index to judge whether putty can be used as water resistance of interior wall or putty of exterior wall. When the amount of latex powder was lower than 4%, with the increase of the amount of latex powder, the water absorption showed a downward trend, and the effect was obvious. When the dosage is more than 4%, the water absorption rate decreases slowly. The reason is that cement is used as the binding substance in the putty. When the redispersible polymer powder is not added, there are a lot of voids in the system. It can form a film to block the gaps in the putty system, so that the surface layer of the putty can form a denser film after being scraped and dried, which can effectively prevent the infiltration of water, reduce the amount of water absorption, and enhance its water resistance. When the amount of latex powder reaches 4%, the polymer emulsion after redispersable latex powder can basically completely fill the voids in the putty system and form a complete and dense film, so that the water absorption of the putty decreases with the increase of the amount of latex powder. The increase becomes flat.
Considering the influence of latex powder on the bonding strength and water resistance of putty, as well as the consideration of the price of latex powder, the most suitable amount of latex powder is 3% to 4%, and the putty has high bonding strength and good water resistance. The emulsion polymer after redispersion of the latex powder can basically fill the voids in the putty system and form a complete film, so that the inorganic materials in the whole putty system can be bonded relatively completely, and there are basically no voids, so it can significantly reduce the amount of putty. water absorption.
Post time: Feb-20-2025