Redispersible polymer powder (RDP) is one of the indispensable and important additives in modern dry-mixed mortar systems, especially in tile adhesives. It is an organic polymer that converts emulsion into powder through a spray drying process. It has good redispersibility and can re-form a stable emulsion after mixing with water, thereby giving the mortar excellent bonding properties, flexibility and construction performance.
1. Mechanism of action of RDP in tile adhesive
Tile adhesive is a dry-mixed mortar product used to bond tiles to the surface of the base, mainly composed of cement, fine aggregate, thickener, polymer additives, etc. Among them, RDP, as a polymer modifier, can significantly improve the comprehensive performance of tile adhesive. Its mechanism of action is as follows:
1.1. Enhanced bonding strength
The polymer film formed by RDP after hydration can penetrate into the microporous structure of the base to form a mechanical bite, and synergize with the cement hydration product to enhance the bonding strength between tile adhesive and tiles and the base surface.
2.1. Improve flexibility
The polymer film has good flexibility and can effectively absorb the stress caused by thermal expansion and contraction or slight displacement of the base layer to prevent the tiles from cracking or falling off.
2.3. Improve construction performance
RDP prolongs the operability time of tile adhesive, improves lubricity and construction feel, and improves construction efficiency.
2.4. Improve crack resistance and impermeability
The polymer film can fill the capillary pores in cement mortar, reduce porosity, and improve crack resistance and impermeability.
2.5. Improve durability and water resistance
RDP enhances the resistance of the mortar system to the external environment (such as humidity, high temperature, freeze-thaw, etc.) and prolongs the service life of tile adhesive.
2. Performance advantages of RDP
The use of RDP in the formulation of tile adhesive has the following significant advantages:
High bonding strength: significantly improves the bonding strength of tile adhesive to tiles (including vitrified tiles, polished tiles, etc.), and adapts to a variety of base surfaces.
Adapt to different environments: RDP gives tile adhesive good water resistance, freeze-thaw resistance, and aging resistance, and is suitable for various indoor and outdoor construction environments.
Strong flexibility: Suitable for high-demand scenarios such as thin-layer construction, large-size tiles, and tiles on the wall.
Environmentally friendly and safe: RDP is a non-toxic and odorless material that meets the environmental protection requirements of green building materials.
3. Recommended dosage and formula reference
The recommended amount of RDP should be determined according to the performance level, application scenario and formula system of the tile adhesive. The general range is as follows:
Ordinary tile adhesive (C1 type): The recommended addition amount is 1.5%~3% of the total weight of the glue powder.
High-performance tile adhesive (C2 type): The recommended addition amount is 3%~6%, or even higher.
Flexible tile adhesive (S1/S2 type): The addition amount can be as high as 6%~10% to improve flexibility and displacement capacity.
Reference formula (example of C2 grade tile adhesive):
Ordinary Portland cement: 40%
Quartz sand (0.1-0.3mm): 50%
RDP: 4%
HPMC: 0.3%
Anti-slip agent: 0.1%
Defoamer: appropriate amount
Water retaining agent/other additives: fine-tuning according to needs
4. Applicable tile types and substrate conditions
The tile adhesive modified with RDP is suitable for various types of tiles and substrates, including but not limited to:
Tile types: glazed tiles, polished tiles, vitrified tiles, mosaics, marble, artificial stones, etc.
Substrate types: cement mortar base, cement board, gypsum board, old tile base, concrete board, etc.
The tile adhesive modified with RDP is particularly suitable for the paving of low water absorption tiles and large-sized tiles, which can effectively solve the problem of insufficient bonding strength of traditional cement mortar.
5. Precautions
During the actual production and application process, the following points should be noted:
Choose a suitable RDP type (such as ethylene-vinyl acetate copolymer EVA, acrylic polymer, etc.) to meet different performance requirements.
Keep dry during storage to avoid moisture and agglomeration.
Do not store with highly alkaline materials for a long time to prevent performance from being affected.
Mix evenly to avoid uneven distribution of powders leading to unstable performance.
As the core functional material in tile adhesives, redispersible polymer powders greatly improve the bonding strength, flexibility and durability of tile adhesives, meeting the needs of modern buildings for high-performance tile paving materials. In the future, with the development of building industrialization, the application of RDP in tile adhesives and more dry-mixed mortar products will become more and more extensive, and its performance and environmental advantages will continue to promote the building materials industry to a higher level.
Post time: Jul-14-2025