For more than 160 years, in the Chartreuse mountain range in France, an exceptional source of stone has been mined for the manufacture of Prompt natural cement. This limestone mountain range to the north of Grenoble in France is part of the sub-Alpine mountain range. It is made up of sedimentary strata which were folded and deformed during the Alpine orogeny.
After grinding, the pieces from the underground quarries, of a grade of between 0 and 150mm, are mixed with a set quality of coal before being put into conventional vertical kilns.
After firing similar to that used for natural hydraulic limes (NHL), the stone, which contains very little quicklime in contrast to HLs, does not undergo extinction. It is for this reason that is called “natural cement”, not “natural hydraulic lime”.
With its natural chemical composition, natural prompt cement is part of the large family of natural cement also called roman cement.