Tests and researches on building stones

In 1941, the "Association Francaise de Normalisation" (French Association of Standardization) decided to create a Commission for the purpose of writing out a standard for building stones. When this Commission met under the chairmanship of Mr. Pol Abraham, Architect, they realized how far behind was our precise technical knowledge of this kind of material, and found the necessity of determining exactly the testing and acceptance methods. They expressed the wish that a careful study of the subject be entrusted to a specialized laboratory. This wish was received by the Ministry of Production, which, after an agreement with the competent organizing committees, entrusted our laboratory with this work. The main object was to establish the difficulty of stone-cutting in order to permit a classification of the stones according to the difficulty met when working them up into shape, to refer the other technical properties of the stones to this property, and finally to see what relation exists between the figures obtained.

To this end nine stones were chosen by the Commission, from the hardest to the softest: Hauteville, Comblanchien, spotted Larrys, yellow Massangis rock, Euville rock, fine-grained Lavoux, soft Maximin rock, "banc royal" Mery, and "bane royal" Billy. Each type of stone included three large blocks of 0.75 by 0.75 by 0.5 meters to be dressed by hand by specialized workmen, the difficulty of stone-cutting being determined by the time spent for the dressing and preparation of the surfaces. After this operation, detail of which will be given later, we had an important quantity of material which we were to use to the best advantage. I thought that it would be interesting to determine on each one the maximum of physical, chemical and mechanical tests in order not only to be able to compare them in precise conditions, but also to set up each sample as a standard intended for future studies. In other words, each element in the mentioned list must, in my mind, be able to serve in the future as reference to which we will compare the other kinds of calcareous stones used for building. As all the available material was not used, we were able to keep some as a reserve in case later comparisons would be necessary.