In situ mechanical characterization of the mortar in masonry buildings with drams

This paper presents the first results of a research project carried on to validate a Non Destructive Test (NDT) to determine the in situ mechanical characteristics of mortar in historical masonry buildings. On the basis of the compositions of historical mortars, the most common used in Tuscan buildings, there were produced 15 types of mortar with different mechanical characteristics, obtained with 5 classes of lime (hydraulic and aerial) and river sand with 3 grading curves. For each class of mortar there were obtained 15 samples, 6 of which were subjected to flexural and compression tests and the other 6 to the Drilling Resistance Measurement System (DRMS). The DRMS is the device that performs the drilling and measures the resistance to the perforation of the material object being tested. During the test the resistant force to the perforation is measured with continuity, maintaining constant the rotational speed and the penetration rate. The result is a curve that shows the drilling resistance profile. The goal of this research project is to validate a correlation between the sizes measured through DRMS and the mechanical characteristics of mortar in masonry buildings.