Questions and answers from the GMA Techline
Asphalt over geomembrane?
We have a project where we want to place asphalt concrete over a 40mil-thick HDPE geomembrane. The asphalt concrete is 3in.-thick and would be the lining for a surface water ditch. On the outside of the ditch, we have a pavement section (asphalt concrete over aggregate) that is underlain by a cushion geotextile, which is, in turn, underlain by the geomembrane.
The owner has asked if placing the asphalt concrete over the geomembrane would affect the geomembrane. I have seen a paper from the 1990s where liquid sulfur was placed over a geomembrane for the sulfur pads in the oil industry in Canada. But I was wondering if there is any experience/references with asphalt concrete placed on geomembrane.
(Albert | Georgia)
Although we have never evaluated the situation you describe, my thoughts go to
the temperature of black geomembranes on hot summer days and the temperature is about that of hot mix asphalt as supplied by trucks for street paving. So I don’t think this will be a problem.
A different issue, however, is how to traffic the geomembrane without damaging it and how to handle the waves formed in the geomembrane. As you know, waves are always troublesome and if they are advancing as the hot-mix asphalt is placed, it could get ugly.