Double flat jack tests

The test with two parallel flat jacks (double flat jack test) allows to estimate the elastic limit and the deformability characteristics of a representative sample of masonry under compression. Two parallel cuts, preferably carried out along the mortar joints and distant each other approximately 50-70 cm, allow the insertion of two flat jacks connected to the hydraulic circuit of a manual pump. The so isolated sample of masonry is subjected to cycles of loading and unloading, with increasing levels load, and its deformations are measured using four vertical and a horizontal displacement transducer. Detected deformations plotted versus the pressure applied to the flat jack allow to determine the modulus of elasticity and to draw the curve of load/deformation of the tested masonry panel.

Reference standards: ASTM C 1197–14a; RILEM TC177 MDT.D.5.