The Film Formation Process of RDP in Cement Mortar

The film formation process of Redispersible Polymer Powder (RDP) in cement mortar involves several stages that contribute to the development of a cohesive and durable polymer film. Here’s an overview of the film formation process:

1. Dispersion: Initially, RDP particles are dispersed uniformly in the aqueous phase of the cement mortar mix. This dispersion occurs during the mixing stage, where RDP particles are introduced into the mortar mixture along with other dry ingredients.
2. Hydration: Upon contact with water, the hydrophobic polymer particles in RDP begin to swell and absorb moisture. This process, known as hydration, causes the polymer particles to soften and become more pliable.
3. Film Formation: As the mortar mixture is applied and begins to cure, the hydrated RDP particles coalesce and fuse together to form a continuous polymer film. This film adheres to the surface of the mortar matrix and binds the individual particles together.
4. Coalescence: During the curing process, adjacent RDP particles come into contact and undergo coalescence, where they merge and form intermolecular bonds. This coalescence process contributes to the formation of a cohesive and continuous polymer network within the mortar matrix.
5. Crosslinking: As the cement mortar cures and hardens, chemical crosslinking may occur between the polymer chains in the RDP film. This crosslinking process further strengthens the film and enhances its adhesion to the substrate and other mortar components.
6. Drying and Consolidation: The cement mortar undergoes drying and consolidation as water evaporates from the mixture and the cementitious binders cure. This process helps solidify the RDP film and integrate it into the hardened mortar matrix.
7. Final Film Formation: Upon completion of the curing process, the RDP film fully develops and becomes an integral part of the cement mortar structure. The film provides additional cohesiveness, flexibility, and durability to the mortar, improving its overall performance and resistance to cracking, deformation, and other mechanical stresses.

the film formation process of RDP in cement mortar involves hydration, coalescence, crosslinking, and consolidation stages, which collectively contribute to the development of a cohesive and durable polymer film within the mortar matrix. This film enhances the adhesion, flexibility, and durability of the mortar, improving its performance in various construction applications.