WATER CUT-OFF BARRIER

Impervious cut-off are installed by removal of in-situ material, replaced with engineered materials with extremely low permeability, or by modifying the permeability properties of the existing soil.

The main feature of plastic diaphragms, that use self-setting water and cement or bentonite mixes, is that they guarantee a barrier with a low level of permeability and whose highly plastic properties make them capable of supporting subsequent ground settling movements without breaking or cracking. The thickness of plastic diaphragms varies from 500 to 120 mm, and they are undoubtedly the most widely used for the construction of soil containment barriers.

Plastic diaphragms can be integrated with a HDPE membrane, that is a sheet of high density polyethylene inserted into the plastic diaphragm. Containment walls containing this synthetic material guarantee extremely high levels of imperviousness, and greater resistance to certain contaminating agents. The maximum installation depth is about 30 metres.

Barriers of secant piles techniques are mainly applied in those situations where the logistics of the project make it difficult to construct a diaphragm by panels. Generally they are used to produce walls of piles with diameters varying from 600 to 1.500 mm, constructed using quick, self-setting mixes or concrete.