BITUMINOUS GEOMEMBRANE FOR ROAD DITCHES
Construction on the A63 motorway section between Bordeaux and the Spanish border, which consisted of widening the RN10 (2×2 lanes) into a 2×3 lane motorway by constructing an emergency lane.
REQUIREMENTS
- The A63 motorway is a busy road (between 6,000 and 9,000 trucks per day), so safety was the number one priority.
- Work carried out on more than 104 km.
- Fully watertight join between the hard shoulder and the ditches.
- The membrane had to be able to accommodate and retain the topsoil on slopes of 2 to 3 metres horizontally and 1 metre vertically.
Membrane installed mechanically. Installed directly on the ground without geotextile. The geomembrane’s mass and the absence of a geotextile made it possible to secure the road on schedule, avoiding the risk of leakage due to the wind.
Saving time was also an advantage with a rate of 2,000 linear metres/day. The BGM was anchored at the ditch head ditch by metal staples inserted every 5 metres. COLETANCHE’s inner geotextile did not tear when the staples pierced it. The bitumen even tended to tighten around the puncture (self-healing).
The topsoil was laid mechanically and then manually raked to the recommended thickness (20 to 30 cm). The topsoil protected the geomembrane and was laid without geotextile or geogrid. Grass was then seeded in the ditch over the entire structure. The vegetation stabilises the topsoil and provides a pleasing appearance.
