This paper deals with an innovative methodology dedicated to the study of historical mortars. Gathering macroscopic observation, petrography in thin sections, chemical analyses as well as physical and mechanical data namely obtained with non destructive technologies developed for the petroleum industry, it allows cross-interpretation that can effectively contribute to archaeological research through correlations with the age, the function, the technology and the provenance of each mortar sample collected on a studied site. Following a synthetic description of the proposed approach, a practical application is illustrated on the site of a mediaeval fortress located in Belgium.