The flat jacks test, allow us to evaluate the in situ stress state and to mechanically characterize masonry as required by the Technical Standards for Construction. With reference to Table C8A.2.1 Standards, the test is used to determine the average compressive strength f_m, the normal elastic modulus E and the shear modulus G. The test is a non-destructive technique.

The test with flat jacks is divided generally in two stages:

• with single jack, in Phase 1 of the test, you can determine the only operating stress;
• with the double jack, in Phase 2, you can determine the compressive strength fm, the elastic modulus E and the normal shear modulus G.

The testing technique with the flat jack can certainly be defined as a non-destructive, at the end of the test, after removing the equipment, the layers of mortar can be easily restored.