Dimensional variations of Roman Masonry Subjected to wetting-Drying Cycles

Many Roman monuments made of opus caementicium are subjected to wetting and drying phenomena caused by water or/and humidity from the ground. The action of water impregnation on the hypothetical dimensional changes in this Roman concrete has not been considered in the literature and no experimental data are available. The purpose of this work was the evaluation of the effect of wetting and drying cycles in a number of cores taken from an ancient Roman monument (Domus Tiberiana in the Palatine, Rome). The concrete samples were made of a pozzolanic mortar with large pieces of tuff, marble and bricks. In spite of some differences in their composition, the behaviour of the cores was similar and, generally, quite constant during the experimental cycles. On the average, the length variation was about 3–4%,or 3–4mm for each metre and, when related to high structural walls and monuments, the possible dimensional changes were quite impressive.