Redispersible polymer powder (RDP) is an extremely important functional additive in modern dry-mixed mortar systems. It is widely used in tile adhesives, self-leveling mortars, plaster mortars, repair mortars, exterior insulation system mortars (EIFS/ETICS) and other products. The addition of RDP can significantly improve the construction performance, bonding performance and mechanical properties of mortars, improve the overall mortar quality and durability, and has become one of the key raw materials for high-performance dry-mixed mortars.
1. Basic characteristics of Redispersible polymer powder
Redispersible polymer powder is a powder material based on polymer emulsions and prepared by spray drying. It can be redispersed in water to form a stable emulsion and restore its original polymer properties. Its main components include polymer matrix (such as vinyl acetate-ethylene copolymer EVA, acrylate, styrene-acrylate, etc.), protective colloids (such as polyvinyl alcohol) and some additives.
2. The core function of Redispersible polymer powder in mixed mortar
2.1. Enhanced bonding
The polymer particles in RDP form a continuous flexible film after the mortar is hydrated and hardened, which is tightly combined with inorganic cementitious materials (such as cement), and can effectively improve the bonding strength of the mortar to the base and covering (such as tiles, insulation boards, old concrete, etc.). Especially in low water absorption base surfaces or high temperature dry environments, RDP provides stronger interfacial adhesion.
2.2. Improved flexibility and crack resistance
The polymer film formed after adding RDP to the mortar has good flexibility, can effectively absorb and release stress, resist cracking caused by thermal expansion and contraction or micro-deformation of the base, and improve the crack resistance of the overall system. This is especially important for scenes with high requirements for crack resistance, such as exterior wall insulation mortar and repair mortar.
2.3. Improved construction performance
The Redispersible polymer powder gives the mortar a better construction feel, making it easier to spread, smooth and shape. At the same time, RDP can improve the lubricity and workability of mortar, reduce the phenomenon of hardening during construction, and improve operational efficiency.
2.4. Enhance water resistance and alkali resistance
The polymer film has certain hydrophobic properties, which can reduce the water absorption rate of mortar, prevent excessive loss of water, and improve overall water resistance. In alkaline environments (such as cement systems), RDP can also maintain good stability and is not easy to decompose and deteriorate, thereby extending the service life of mortar.
2.5. Improve wear resistance and impact resistance
The presence of polymer film enhances the density of mortar, making it more resistant to external mechanical impact and friction damage. Especially in floor mortar or surface protection mortar, RDP can effectively improve wear resistance.
2.6. Promote water retention and control shrinkage
The protective colloid and polymer particles in RDP have good water retention in the mortar system, which can extend the open time of mortar, facilitate the full hydration of cement, and reduce early shrinkage cracking caused by water loss. At the same time, this water retention is particularly critical for thin-layer construction, helping to ensure final strength and adhesion.
3. Common application areas
Tile adhesives: Improve initial adhesion and final bonding strength, improve flexibility, and adapt to large-sized tiles and difficult-to-bond substrates.
Plastering mortar: Enhance adhesion and crack resistance, and adapt to a variety of base layers (concrete, brick walls, insulation boards, etc.).
External insulation system mortar (EIFS): Improve the adhesion, flexibility, and weather resistance of the insulation board bonding layer and the plastering layer.
Floor self-leveling mortar: Improve fluidity and wear resistance, and improve interface bonding ability.
Repair mortar and waterproof mortar: Enhance adhesion, water resistance and structural ductility, and prevent water seepage and peeling.
4. Precautions for use
Reasonable ratio: The amount of RDP added is usually between 2% and 6%, and needs to be adjusted according to the specific application scenario to achieve optimal performance.
Avoid high-temperature storage: latex powder is sensitive to temperature, and long-term exposure to high temperature and humidity may cause agglomeration or performance degradation.
Synergistic effect with other additives: RDP is often used with cellulose ether, defoamer, retarder, etc., and attention should be paid to compatibility and stability.
Redispersible polymer powder as a functional additive in mixed mortar, has greatly expanded the application range and performance boundaries of mortar. It plays an irreplaceable role in improving bonding strength, flexibility, construction performance, etc., and is an important technical support for promoting the development of green building materials and high-performance dry-mixed mortar. In the future, with the in-depth development of building energy conservation and sustainable concepts, the application of RDP in mixed mortar will become more extensive and diversified.
Post time: Jul-02-2025