What is a drying accelerator for sand-cement screed?
A drying accelerator for sand-cement screed is an additive mixed into the screed mortar so that the screed dries faster and can receive a finish sooner. It shortens the waiting time before parquet, tiles or a poured floor can be installed.
How does a drying accelerator work?
Standard sand-cement screed needs a lot of water to be workable. For laying tile adhesive, parquet or poured flooring, the residual moisture must be low. With natural drying, the rule of thumb is 1 cm per week — for a 60 mm screed that means almost two months.
A drying accelerator reduces the required water, binds excess water or accelerates hydration of the cement. As a result the screed can be ready for finishing after 1 to 2 weeks. Some products are added to the mixing water; others are pre-mixed dry screeds.
Application
- Renovation — when programmes are tight
- Screeds with underfloor heating — faster warm-up and readiness for finishes
- Tiled floors — residual moisture must be below 2-3%
- Timber floors and parquet — strict moisture limits
- Poured floors — sensitive to residual moisture beneath the finish
Points of attention
- Follow the supplier’s dosing instructions exactly
- Always measure residual moisture with a CM test before installing the finish
- Faster drying must not reduce final strength
- Fast-drying screeds are often stiffer and need careful workmanship
- Not every accelerator suits every finish — check with the manufacturer
Related terms
- Screed
- Anhydrite screed
- Construction moisture
- Hydration
- Cement
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