To improve the bonding strength, flexibility and reduce water absorption of putty, you can refer to the following methods:
1. Improve bonding strength
Optimize the amount of cementitious materials used: The recommended cement content for interior wall putty is not less than 15%, and for exterior wall putty, it is recommended to use at least 25%. Ensure that the active ingredient content of the cement or lime is sufficient to avoid insufficient bonding due to insufficient dosage.
Appropriately use redispersible polymer powder: Select a polymer powder with moderate hardness and ensure sufficient addition. The addition amount of redispersible polymer powder for interior wall putty is generally between 0.3% and 0.8%, and for exterior wall putty, it should be at least 1.5%. Redispersible polymer powder forms a polymer network, enhancing the putty's cohesion and molecular-level adhesion.
Application and Maintenance: After exterior wall putty is applied, curing can be performed by roller coating or spraying to fully hydrate the cement and improve bond strength. Avoid direct sunlight during application to prevent the primer from forming too quickly and affecting permeability. Dilute the primer with water to ensure it fully penetrates the base layer.
2. Improve flexibility
Adjust the polymer-cement ratio: This refers to the ratio of polymer to cementitious material. While maintaining strength, reduce the cement content while increasing the amount of redispersible polymer powder to improve the polymer-cement ratio. Generally, a higher polymer-cement ratio indicates greater flexibility.
Choose the right polymer powder: Select highly flexible redispersible polymer powders, such as ADHES RDP VE3211 or VE3213. These products can effectively improve the putty's flexibility and reduce the risk of cracking.
Optimize the formula: Adding some fine sand to the formula can also improve the putty's flexibility. However, be mindful of the sand's particle size and dosage to avoid affecting other putty properties.
3. Reduce water absorption
Optimizing filler selection: Reducing the amount of highly absorbent fillers (such as calcium carbonate) and increasing the amount of less absorbent fillers (such as quartz powder) can effectively reduce the water absorption of putty.
Adding hydrophobic components: Adding hydrophobic redispersible polymer powders, such as ADHES VE3311 or water repellent P760, to the putty has excellent hydrophobic properties and can significantly reduce the water absorption of the putty.
Improving putty density: Appropriately reducing the amount of air entrained in the putty reduces internal porosity, improves the putty's density, and thus reduces water absorption. Furthermore, ensuring the appropriate amount of cellulose ether added helps improve the putty's water retention and density.
Post time: Sep-19-2025