A method for producing a cement source and associated test device

The method produces a controllably expanding cement, comprising cement, an oxidic, hydrolysable expanding adjunct and mixing water. The quality of the expanding adjunct is chosen by the properties, as determined by the reactivity, thereof, or by the composition of the expanding cement, whereby, based on a desired composition, the relevant conditions at the filling site are taken into consideration and the expansion and consistency properties of the expanding cement are determined experimentally. The quality of the expanding adjunct or the composition of the expanding cement is particularly selected to give the desired expansion and consistency properties, according to the practical making up and the conditions at the filling site.