Redispersible polymer powders are essential additives in mortars that enhance the flexibility, bonding strength and water retention properties of the final product. However, there are many different types of redispersible polymer powders on the market, and choosing the one that suits your specific needs can be challenging.
First, it is necessary to understand the role of redispersible polymer powders in mortars. This product is a copolymer of vinyl acetate and ethylene, spray-dried from aqueous polymer emulsion. The powder is designed to improve the properties of mortars, particularly in terms of flexibility, workability, adhesion and water retention. Additionally, it promotes better cement hydration, reducing the risk of cracking, shrinkage and dusting.
The following are key factors to consider when selecting the right redispersible polymer powder for your mortar application.
Mortar type
The first factor to consider is the type of mortar you plan to use. There are many types of mortar, including cement-based mortar, lime-based mortar or gypsum-based mortar, and epoxy resin mortar. Each has its own specific properties and requirements, which will determine the type of redispersible polymer powder to be selected. Cement mortars are the most common and they require redispersible polymer powders with good water retention, bond strength and workability.
Application method
The application method is also critical when selecting a redispersible polymer powder. Some products are designed for use in dry mix formulations, while others are suitable for wet mix applications. In dry blend formulations, the polymer powder should be able to disperse quickly and evenly to form a stable emulsion with water. In wet mix applications, the polymer powder should have good redispersibility and be able to mix effectively with other additives and cement.
Performance requirements
The performance requirements of the mortar will also influence the choice of redispersible polymer powder. Different applications have different needs for strength, flexibility and durability. For example, if you want to make an exterior wall mortar, you will need a product with excellent water resistance and freeze-thaw stability. Alternatively, if you are using a tile adhesive, you need a redispersible polymer powder with good adhesion and cohesive strength.
Polymer powder properties
Another key factor to consider when selecting a redispersible polymer powder is the performance of the product. Key properties to look for include particle size, glass transition temperature (Tg) and solids content. The particle size of a powder affects its dispersibility and bonding strength. Smaller particle sizes (less than 80μm) provide better water retention, while larger particle sizes (greater than 250μm) provide better workability.
The glass transition temperature (Tg) of a redispersible polymer powder determines its flexibility and adhesion. A Tg above room temperature (25°C) means the powder is rigid, while a Tg below room temperature means the powder is flexible. Redispersible polymer powders with low Tg (below -15°C) are ideal for cold climates where mortars may experience freeze-thaw cycles.
Finally, the solids content of the redispersible polymer powder determines its application rate and the amount of water required for mixing. Higher solids content (over 95%) requires less powder to achieve desired properties, resulting in lower costs and less shrinkage.
in conclusion
Selecting the right redispersible polymer powder for a mortar application is critical to achieving the desired performance and durability of the final product. By considering the type of mortar, construction method, performance requirements and polymer powder characteristics, you can select a product that meets your specific needs. Remember, using the right redispersible polymer powder will not only enhance the properties of your mortar, but also reduce the risk of cracking, shrinkage and dusting, resulting in a long-lasting and beautiful finish.
Post time: Sep-14-2023