CASEA Südanit 280 Alpha Hemihydrate Binder

Südanit 280 Alpha Hemihydrate Binder is a specially formulated calcium sulphate binder suitable for the production of top quality self-levelling (flowing) floor screeds, simply by blending with suitable sand and water on site.

Südanit 280 Alpha Hemihydrate Binder complies with EN 13454-1: 2004 and is CE marked. Südanit 280 Alpha Hemihydrate Screed is suitable for floors in homes, offices, public buildings, and places exposed to similar loads. Südanit 280 Alpha Hemihydrate Screed may be applied as a levelling screed directly onto a load-bearing floor, unbonded on a separating barrier (polythene), or as a floating floor, and is particularly suited in conjunction with underfloor heating or cavity floors. Südanit 280 Alpha Hemihydrate Screed should be covered with a floor finish such as tiles, linoleum, parquet, cork or carpet. If a cement-based adhesive or smoothing compound is required the surface of the screed must first be sealed, using an appropriate acrylic primer/sealer.

Sand should be of approved quality and grading. Trials should always be carried out to optimise the mix design before work commences. The proportion of binder required is 475 – 600kg/m³. Sufficient sand is required to produce 1m³ of screed, with sufficient water added to produce a flow spread diameter of 230-260mm. A typical starting point mix design is 600kg Binder, 1200kg sand (dry weight), and 330L water per m³. All materials should be adequately mixed to ensure full dispersion of materials without lumps.

Related Downloads

icon-pdf  TDS CASEA Sudanit 280 Binder

icon-pdf  TDS SMET_Tiling Onto Calcium Sulphate Floor Screed_System I

icon-pdf  TDS SMET_Tiling Onto Calcium Sulphate Floor Screed_System II

icon-pdf  Sudanit 280 Alpha Hemihydrate Floor Screed – UFH Commissioning – Floor Screed Drying Schedule

icon-pdf  EPD – CASEA Calcium Sulphate Flowing Screed

icon-pdf SMET Floor Screeds and Compounds Product Selector

Benefits of Sudanit 280 Alpha Hemihydrate Binder

• Smooth Laitance Free Finish
• Pumpable
• Under Floor Heating – Full Encapsulation
• UFH can be commissioned and running during screed application at max. water temp (manifold) of 25 ˚C
• Suitable For Underlayment In Wet Areas
• Reduced Drying Times
• CE Marked
• EN 13454-1: 2004
• 25kg bags and bulk

Technical Details for Südanit 280 Alpha Hemihydrate Binder

Screed Specification EN 13813: 2002
Maximum Thickness 90mm
Minimum Thickness Bonded: 20mm Unbonded: 30mm Domestic: 35mm Commercial: 40mm

Over Underfloor heating Pipes: 25mm (BS 8204-7)

Use (External Use) No
Use (Internal Use) Yes
Compressive Strength (28 days) >25 N/mm²

>30 N/mm²

>40 N/mm²

Flexural Strength (28 days) > 5 N/mm²

> 6 N/mm²

> 7 N/mm²

Bulk Density approx. 1.3 kg/dm³
Flow Rate  230 – 260 mm flow spread diameter (Hägermann cone)
Light foot-traffic approx. 8 hours depending on drying conditions
Partial load-bearing capacity approx. 36 h / 1.5 days dependent on thickness and drying conditions
Open time as screed 30 – 45 minutes depending on ambient conditions
Reaction To Fire A1 Non-Combustible
Packaging bags and bulk
Underfloor Heating Commissioning UFH can be commissioned and running during floor screed application at max. water temperature (manifold) of 25˚C


Available in 25kg bags and bulk

Watch Ireland’s leading floor screed applicator, one of our busiest Smet Supported Partners, install their flowing screed, made using Südanit 280 Alpha Hemihydrate Binder, applied with their state-of-the-art mobile screed factory – click this video:

Floor Screeds & Compounds from Smet Building Products Ltd have been used throughout Europe for over 40 years. Our comprehensive German-made portfolio includes Calcium Sulphate Based Screed BindersSelf Smoothing Calcium Sulphate Based Screeds & Compounds, Cement-Based Screed Binders and Self Smoothing Cement Based Screeds, Lightweight Flowing Screeds & CompoundsMulti-Purpose & Repair Screed Mortars, Rapid drying solutions and SMET screeding equipment and tools for any Domestic, Commercial, Industrial, and Design use. The SMET range has a Floor Screed solution for any building requirement.