1987
6640.015
Not Given
Civil Engineering
Article
American Society of Civil Engineers
1994
October
86
N
After two attempts to reconstruct a sinking roadway were unsuccessful, Illinois DOT engineers completed the project using 900 cu yd of expanded polystyrene foam (EPS) for fill.Atkinson Road in Grayslake collapsed when a 400 ft long section of roadway fell into a peat bog. Two previous efforts to rebuild the road in the fall of 1993 failed because the underlying soils were too weak to support a conventional road base. Using EPS, it was rebuilt in less than three weeks last December, according to the manufacturer.
Polystyrene foam, a material used to make insulated beverage cups and roofing insulation, has been used as road and embankment fill in Europe and Asia for more than 200 years, says Miles Ducore of Polyfoam Packers Corp., Wheeling, Ill. Polyfoam suggested using the blocks for road fill to Illinois DOT’s geotechnical staff.
“We had a peat bog and we needed to raise the road about 5 ft,” says Edward Frank, an Illinois DOT soils engineer. “The road would have settled up to 1 ft, so we used this lightweight EPS as fill. Essentially, we put no extra load on the peat, to prevent settlement. The blocks are light and easy to work with.”
The blocks appear to be holding up, Frank says, although the roadway is still in its season.
EPS was selected after it was compared with other options, including a dry land bridge, geosynthetic fabrics and an alternative fill of expanded shale. Fill was required to shore up the weak clays and moist, soft soils in the sunken roadway, which weren’t strong enough to support the weight of conventional road-building materials. At about 40 lb/cu yd, EPS is lighter than other materials, allowing engineers to reduce the depth of excavation from 12 ft to 3 ft, Ducore says.
EPS was then covered with a 4 in. concrete cap that supports the roadway and protects the EPS from petroleum products, which cause it to dissolve. Ducore says using EPS helps hold down a project’s costs because workers spend less time and effort excavating weak soil. Frank says the cost of EPS was comparable to other lightweight materials, but it was chosen because it was virtually the only product that engineers felt would do the job in this case.
This is the entire article.