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S.S. 318 “Valfabbrica (PG)”

Retaining structures

Project name S.S. 318 "Valfabbrica (PG)" Volume 20.000 m³ expanded clay 0-30 mm Location Valfabbrica (PG), Italy Year 2013-2015
Contractor Carena S.p.A. Designer Anas SpA, GP Ingegneria Srl Owner/Builder Anas SpA


The route for a new road ss 318 km between km 13 and 17 near Valfabbrica (PG) passes through a mountaineous area with risk of landslides. In one of these areas, the design engineers decided that the best solution was to create a lightweight embankment with expanded clay reinforced with geogrids.

Why Expanded Clay:

A lightweight embankment with expanded clay was chosen as a solution, in order to keep load weights on the slope to a minimum, as any increase in weight is dangerous to the stability of the slope. This is also an area with frequent and heavy rainfall throughout the year, expanded clay is a material that drains well and helps to avoid overloading due to water.


The embankment was built with alternating layers of 70 cm of expanded clay with geotextile on top, and  30 cm of granular normal local aggregate ,  each layer of granular normal aggregate was passed over by a  roller to optimize the compaction of the embankment. These layers were repeated for the whole height of the embankment.

Key Issues:

Drainage, Earth preassure, Settlement, and Stability

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