Rapid cement

Quick cement (Engl. Regulated-set cement, jet cement) is a cement , which very quickly abbindet .

Mortars made with quick- setting cement generally have a pot life (processing time) of two to three minutes, solidification occurs after five to seven minutes, but cements with processing times of up to one hour are also considered to be quick-setting cements.

Rapid cement contains a high proportion of calcium fluoroaluminate (11 CaO · 7Al2O3 · CaF2, a variant of Friedel's salt ) and possibly other cement accelerators as well . Rapid cement is not a standardized type of cement according to EN 197-1.

Rapid cement is particularly suitable for repairs and situations in which rapid loading capacity is necessary, such as B. cementing dowels and hooks. It can be used in the DIY sector especially where fast setting times such as plaster of paris , but water and weather resistance and higher load capacity are required. Rapid cements with setting times of around 30 minutes are used e.g. B. the screed renovation , after the renovation , the new floor can often be used normally the next day.

The fast setting time makes it suitable for use in regular construction, e.g. B. impossible in concrete production . On the one hand, even pot lives of around 30 minutes on a large construction site are far too short, as a rule, delivery takes longer. On the other hand, the very short setting time also makes the mortar very warm when it sets, so it tends to form cracks in thicker layers. In addition, the load-bearing capacity of rapid cement is lower than that of normal cement (and, for example, concrete made from it), so that its field of application is limited.