What is the role of RDP in mortar?

RDP (Redispersible Polymer Powder) is a mortar additive and binder. It is a high-molecular-weight polymer powder produced through a spray-drying process. Upon contact with water, it can redisperse into a stable emulsion, restoring its original properties. Its main components are ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl acetate-acrylic acid copolymer (VEOVA), and acrylate polymers, usually supplemented with protective colloids and functional additives.

RDP enhances the performance of dry-mixed mortar through the following mechanisms:

Enhanced adhesion: After redispersement, it forms a polymer film that effectively coats the mortar and substrate, significantly improving bond strength.

Improved flexibility: It imparts a certain degree of deformation capacity to the mortar, reducing cracking caused by temperature changes or external forces.

Improved workability: It enhances the workability and fluidity of the mortar, making it easier to apply and improving construction efficiency.

Improved durability: It enhances the mortar's impermeability, freeze-thaw resistance, and weather resistance, extending its service life.

Inhibited shrinkage cracking: The elasticity of the polymer film can alleviate drying shrinkage stress, reducing the risk of cracking. Main application areas include:

Tile adhesive: Suitable for various wall and floor tiles and low-absorption stone, providing high bonding strength and flexibility.

External wall insulation systems: Used for bonding mortar and plastering mortar, enhancing system integrity and crack resistance.

Self-leveling mortar: Optimizes flowability and adhesion, ensuring a smooth and crack-free surface.

Waterproofing and repair mortar: Improves density and impermeability, ensuring reliable repairs.

Plastering and leveling mortar: Improves workability, resists shrinkage cracks, and extends service life.

Precautions for use:

Ensure RDP is compatible with cement-based systems to avoid delamination or adverse reactions.

Control the temperature and humidity of the application environment to facilitate polymer film formation.

Store in a dry, cool place to prevent moisture absorption and clumping; stir thoroughly before use.

Adjust the dosage according to actual project requirements; excessive use may affect mechanical properties and increase costs.

With the development of green building and building materials industrialization, RDP is continuously evolving towards environmental protection, low VOC, and high performance. Modified polymer powders with functions such as self-cleaning, antibacterial, mildew prevention, and flame retardancy are also emerging, further expanding their application prospects in high-performance building materials.