Raw Materials For Calcium Sulfate Flowing Screeds

Calcium sulfate flowing screeds are enjoying increasing popularity. With an overall positive growth in the floor screed mortar market in 2019 with a gain of 2% compared with 2018 the growth rate of calcium sulfate flowing screeds is higher on average than that of conventional cement floor screeds. This is due, among other things, to the advantages of this type of floor screed, which can in turn be attributed mainly to the raw materials used. One outstanding property of calcium sulfate flowing screeds is that large floor screed areas can be laid with virtually no joints in a free-flow consistency that can be placed easily and by machine. The crucial requirement for this is provided by the characteristic property of the calcium sulfate binder. It hardens with the formation of high strengths and low stresses and virtually no deformation while drying. Calcium sulfates with setting properties are now used for producing building plasters, stucco, plasterboard, gypsum wallboard and calcium sulfate floor screeds as well as modelling and moulding plasters. Calcium sulfate floor screeds can only be produced with high-strength calcium sulfate binders. In Germany they are produced using natural and industrial raw materials, which have to satisfy strict demands on quality, uniformity and long-term availability. The basis for this is created by the fact that the calcium sulfate flowing screed can actually realize its characteristic advantages during placement and in the subsequent utilization phase as an important element of the floor structure. Synthetic anhydrite is obtained as a co-product in the production of hydrofluoric acid. The starting materials for the production of hydrofluoric acid are sulfuric acid and fluorspar, a mineral with a colouring that also affects the subsequent colour of the synthetic anhydrite. Calcium sulfate flowing screeds are classified as particularly sustainable and environmentally friendly floor screed building materials because of their relatively low energy consumption in the production of the binders used. For the same performance they can be installed in thinner layers. For the same area this results in a lower material consumption and an even lower power consumption. For example, virtually only half the amount of CO₂ is emitted for the production of a 35 mm thick calcium sulfate flowing screed when compared with a 45 mm thick cement floor screed.* And, flowing screeds are usually delivered to the building site as factory-mixed mortar in silos or truck mixers or in Mixmobils. This means no packaging waste.