Comparison of non destructive in situ techniques for vertical load strength assessment in masonry walls

Comparisons are made between the well-known nondestructive technique of flat-jack tests used in masonry, and the recently introduced PNT-G penetrometer, best suited to in situ measurements of mortar strength. A method is proposed for determining the stress-strain response law of masonry walls subjected to vertical loads, by means of PNT-G measurements and monoaxial tests on the blocks making up the masonry structure. The technique is checked on a trial sample of already existing buildings and found to be particularly effective in the case of masonry faces made up of mortar whose resistance is low comparing to that of blocks.