Mechanochemical syngenite as hydration accelerator for anhydrite-based self-levelling floor screeds

Abstract The performance of mechanochemical syngenite applied as hydration accelerator for fully formulated anhydrite-based self-levelling floor screeds was evaluated regarding workability (open time), setting time, compressive strength, shrinkage and microstructural development. Results demonstrate that mechanochemical syngenite substantially increases early and final strength development, but generally reduces workability (fluidity) and shortens the open time. However, addition of a very minor amount of sodium polyphosphate retarder eliminates these disadvantages without hampering the accelerating effect of syngenite. Hence, when combined with NaPP syngenite was found to present a highly effective hydration accelerator for anhydritebased building materials.