mortar additive hpmcMay 11th 2023
What Is CTA?
Cementitious tile adhesive (CTA) is a type of adhesive used for ceramic tile installations. It typically consists of Portland cement or blended cement, silica sand, fillers, and additives such as redispersible polymer powder (RPP/RDP). CTA provides strong adhesion between tiles and substrate surfaces such as concrete or drywall. It also reduces water absorption into the substrate surface and prevents cracking due to shrinkage in large-format tiles during drying.
How Does RPP/RDP Work?
Redispersible polymer powder (RPP/RDP) is a type of synthetic polymer that improves the physical and mechanical properties of CTA when combined with other cementitious components. RPP/RDP works by providing additional adhesion strength between tiles and substrate surfaces while also reducing the amount of water absorption into the substrate surface. Additionally, RPP/RDP helps to reduce shrinkage in large-format tiles during drying which prevents cracking due to thermal stresses.
Formulation Of CTA With The Inclusion Of RPP/RDP
When formulating CTA with RPP/RDP, it’s important to consider factors such as water retention capacity, workability time, open time before setting occurs, final set time after application onto the substrate surface, minimum thickness requirements for application onto walls or floors, etc. It’s also important to consider which type of cement should be included in order to achieve desired performance characteristics.
Generally speaking, Portland cements are preferred since they provide better hydration characteristics than blended cements do. Additionally, different types of fillers can be added depending on the desired end result; some fillers are designed specifically for improved adhesion while others are designed for improved waterproofing capabilities. Finally, additives such as accelerators may need to be included in order to speed up setting times if desired.