Redispersible polymer powder (RDP) is an additive commonly used in building mortar. It is a high molecular polymer, usually in powder form, with good solubility, adhesion and plasticity, which can greatly improve the performance of building mortar. RDP is widely used as a reinforcing agent for building mortar, especially in the field of dry mortar.

1. Definition and characteristics of RDP
RDP is a polymer powder made by spray drying of aqueous emulsion. It has excellent solubility and dispersibility, and can be quickly redispersed in the presence of water to restore the properties of the emulsion. Common types of RDP include ethylene-vinyl acetate copolymer (VAE), acrylates (Acrylates), polystyrene (Styrene), etc.

RDP powder can be mixed with other ingredients such as cement, gypsum, fillers, etc. to form a building mortar with higher strength, better crack resistance and better workability. Its addition amount is usually between 1%-5%.

2. The role of RDP in building mortar
Improving adhesion: RDP has good adhesion properties, which can enhance the adhesion between mortar and substrate, and reduce the occurrence of shedding and cracking. Especially in applications such as exterior wall coatings and tile adhesives, RDP can effectively improve the bonding strength.

Improving flexibility: As a plasticizer, RDP can improve the flexibility of mortar, avoid excessive shrinkage or cracking of mortar during hardening, and extend the service life. This is especially important for outdoor environments or areas with large temperature changes.

Improving construction performance: Building mortar using RDP usually has better construction performance. For example, the workability and operability of mortar will be improved, and construction workers can more conveniently apply and lay mortar. In addition, the addition of RDP can also improve the adjustability of mortar to meet different construction needs.

Improving water resistance and frost resistance: RDP can enhance the water resistance of mortar, make it more resistant to water and humid environments, and reduce the impact of moisture on mortar strength. At the same time, the introduction of RDP helps to improve the frost resistance of mortar, so that mortar can still maintain good performance in low temperature environments.

Improve crack resistance: Due to the elasticity of RDP, it can form a tiny polymer film during the hardening process of the mortar, which helps prevent the mortar from cracking due to temperature differences or external forces. It enhances the crack resistance of the mortar and reduces the cost of maintenance and repair.

Improve durability: The introduction of RDP can not only improve the initial performance of the mortar, but also enhance the long-term durability of the mortar, so that the building can maintain a good appearance and functionality during long-term use.

3. Application of RDP in different types of building mortars
Tile adhesive: Tile adhesive is a common dry powder mortar. The addition of RDP can significantly enhance its bonding strength and ensure a firm bond between tiles and walls. RDP can provide stronger anti-slip properties and improve the stability of tiles after paving.

Exterior wall coatings: RDP can be used as a tackifier and plasticizer in exterior wall coatings, which can improve the adhesion and weather resistance of the coating, so that the exterior wall coating can better maintain stability when facing the erosion of the external environment and extend the service life of the coating.

Mortar repair material: For the repair of old buildings, RDP, as an important component of repair mortar, can enhance the crack resistance and durability of mortar. It can adapt to different repair environments and provide better compressive and tensile strength.

Dry mortar: Dry mortar products often need to use RDP to improve their stability during production and transportation. With the introduction of RDP, dry mortar can better maintain its performance and quickly restore its function when needed.

Gypsum mortar: In gypsum mortar, the addition of RDP helps to increase the hydration rate of mortar, making it easier to operate during construction. RDP can also improve the adhesion and surface hardness of gypsum mortar and prevent cracks due to humidity changes.

4. Advantages of RDP
Improve the performance of mortar: RDP can significantly improve the comprehensive performance of mortar, including adhesion, flexibility, crack resistance, etc., and improve the workability and service life of mortar.

Environmentally friendly: RDP is a powder dried from water-based emulsion, which is usually non-toxic, odorless and meets environmental protection requirements. It does not release harmful substances during use and is environmentally friendly.

Reduce labor costs: Since RDP enhances the construction performance of mortar, the work can be completed more efficiently during the construction process, reducing working hours and labor costs.

Economical: RDP is a relatively low-cost additive that can significantly improve the quality of mortar without increasing too much cost.

As a building mortar additive, redispersible polymer powder (RDP) can significantly improve the adhesion, flexibility, construction performance, crack resistance, water resistance and durability of mortar. Its wide application in various construction fields, especially in dry mortar, tile adhesives, exterior wall coatings, gypsum mortar and other products, has shown great market potential. With the growing demand for high-performance materials in the construction industry, the use of RDP will become more and more popular and become one of the important technologies to improve building quality and construction efficiency.