A robust, monolithic bond between your concrete slab and engineered screed is foundational. Debonding, hollow spots, or screed failure starts at the interface. Topcem Pronto Slurry creates that critical, reliable connection. It ensures your Topcem Pronto screed achieves maximum adhesion, wet-on-wet, to the concrete substrate.

Why this product exists

Topcem Pronto Slurry is purpose-built as the essential bonding interface for Mapei’s Topcem Pronto engineered screed system. It ensures the screed forms a durable, integrated layer with the concrete substrate. This isn't a general-purpose bonding agent; it’s specifically tuned to work in tandem with Topcem Pronto’s hydration profile, creating a perfect chemical and mechanical bond that prevents the common failures associated with poorly adhered screeds.

The numbers that matter

  • Specific Mixing Ratios: The precise formulation requires mixing with either Planicrete (1 part Planicrete, 1 part water, 3 parts slurry by weight) or Planicrete SP (2 parts SP, 3 parts slurry by weight). These ratios are critical for achieving the correct consistency and ensuring the slurry cures in sync with Topcem Pronto, guaranteeing optimum bond strength and reliability.
  • Application Thickness: Apply the slurry in a continuous, even layer of 2-3 mm. This specific thickness is engineered to create a sufficient bonding key without creating a thick, weak layer that could compromise the screed’s integrity.
  • Wet-on-Wet Application: The performance of Topcem Pronto Slurry relies on applying the Topcem Pronto screed while the slurry is still fresh. This wet-on-wet technique creates a truly monolithic bond, eliminating potential cold joints or delamination points that can lead to screed failure over time.

What it's like to use

Preparation begins with a structurally sound, clean, and completely cured substrate, free of all contaminants. Mix the slurry by gradually adding the powder to the liquid (Planicrete/water or Planicrete SP) in a clean container, blending until homogeneous. Allow it to slake for 3-4 minutes, then briefly remix. Apply the slurry using a large flat brush, scrubbing brush, or a 6x6 mm square-notched trowel to achieve the 2-3 mm layer. The critical step is to apply the Topcem Pronto screed immediately, while the slurry is still fresh. Tools clean easily with water before the product sets.

Where this product excels

Topcem Pronto Slurry delivers reliable performance for bonded Topcem Pronto engineered screeds across a range of demanding conditions. It is suitable for both indoor and outdoor applications where screed integrity and adhesion to the concrete substrate are paramount. This includes commercial flooring installations, high-traffic areas, and any project where the performance of the screed system cannot be compromised.

How it fits in a real system

This slurry is the first critical step in the Mapei Topcem Pronto engineered screed system. It acts as the indispensable bonding bridge, applied directly to the concrete slab before the Topcem Pronto screed. Its role is to prepare the substrate, creating a chemical and mechanical key that ensures the screed adheres properly and performs as a durable, load-bearing layer. Without this specialised slurry, the Topcem Pronto screed would not achieve its designed bond strength and long-term stability.

Choose this when

  • When installing a bonded Topcem Pronto engineered screed: This slurry is formulated specifically for maximum adhesion to concrete substrates within the Topcem Pronto system.
  • When a robust, monolithic bond is critical: Choose this product to prevent debonding and ensure the long-term performance of your engineered screed.
  • When applying screed wet-on-wet: Its design ensures optimal performance only when the Topcem Pronto screed is applied while the slurry is still fresh.

Don't use this when

  • Not for: Concrete substrates subject to rising damp, which can compromise bond integrity and screed performance.
  • Not for: Use if the screed application cannot be performed wet-on-wet, as the dried slurry will not provide adequate adhesion.
  • Not for: Mixing with binders or aggregates not specified in the instructions, as this alters the engineered curing profile and bond strength.
  • Not for: Areas subjected to exceptionally high mechanical stresses where an epoxy bonding adhesive like Eporip would be more suitable.