Development of a methodology for the characterization of historical mortars in the Walloon Region (Belgium)

A wide scale program on the suitability of mortars formulation for heritage buildings in the Walloon Region has been undertaken at University of Mons, in collaboration with the Restoration Directorate of Public Service of Wallonia (SPW) to improve the restoration habits in order to guarantee the permanence of the patrimonial monuments. This program has pointed out the lack of mechanical information available on historical mortars, and the difficulties to characterize the mechanical properties on small scale mortars samples. Any normalized testing procedure is adapted for such particular applications. Some alternative characterization techniques have been investigated to evaluate the possibility to use them in this project. Experimental procedures have been chosen to characterize some physical and mechanical properties. The physical characterisation is based on the measurement of the apparent density, the total porosity and the sonic P-waves velocity, while the mechanical properties are estimated based on scratching and micro-drilling techniques.The proposed paper presents a global methodology from the collect, the registration and the macroscopical description of the mortars samples on the field to the experimental physical and mechanical characterisations performed in laboratory. To perform a more global approach, from the studying of historical samples to the prescription of a formulation for the restoration, two significative case studies will be presented and show the interest of the methodology to improve the practices on the restoration sites.