Geofoam Offers Performance and Efficiency for Bridge Reconstruction

Modern Contractor Solutions Magazine

Modern Contractor Magazine, April 2009

Originally published in Modern Contractor Magazine, April 2009

Full article (pdf)

Known as one of the Top 10 High-Tech metropolitan areas in the nation (as cited by Newsweek magazine), the city of Omaha, Nebraska, leads the nation by pursuing the most innovative technologies in virtually every field imaginable, not the least of which is road construction.  With more than 100 road construction projects currently under contract, the Nebraska Department of Roads (NDOR) strives to utilize the most effective and efficient construction products in its continuous improvement of the state’s road structures.

That is why, when NDOR officials decided to reconstruct the Pacific Street Bridge, they chose to use expanded polystyrene (EPS) geofoam for the below-grade void fill portion of the construction project.  By spring of 2008, Pacific Street, which provides commuters with convent access to and from downtown Omaha, was experiencing significant traffic congestion, decreasing the ease and efficiency of local commutes.

The Pacific Street Bridge, which spans Interstate 680, experienced the heaviest congestion, affecting the flow of both local and regional traffic.  It became apparent to NDOR officials that this situation required a remedy that would not only be effective in streamlining the flow of traffic, but could also be completed in a short time frame.

The NDOR decided to widen the bridge by adding one lane, while maintaining the current length of the bridge.  Construction, which was managed by Hawkins Construction Company, a local Omaha-based construction contractor, began in March 2008.

The existing 2:1 slope protection was removed and replaced by abutment walls allowing room for t he needed extra lane

Pacific Street Bridge, Nebraska:  The existing 2:1 slope protection was removed and replaced by abutment walls allowing room for the needed extra lane

In order to build an additional lane without lengthening the bridge, Hawkins had to first construct abutment walls at each end of the bridge.  To avoid creating excessive lateral pressures on the new abutments, a lightweight void fill material was needed for filling in the embankments.  Because of this requirement, the NDOR chose to use geofoam for this portion of the application.

After comparing a number of geofoam manufacturers, Hawkins Construction chose to use geofoam manufactured by Insulfoam, the nation’s largest manufacturer of block-molded expanded polystyrene.

“It was vital that we use a product that would not increase the amount of lateral load placed on the new abutments,” said Omar Qudus, NDOR Geotechnical Engineer.  “We chose to use geofoam because it would do just that, and would enable us to fill the embankments while still being able to build the additional lane.”

As this was the NDOR’s first specification of geofoam, Qudus and his team consulted multiple geofoam manufacturers in order to ensure that the geofoam was used correctly and in a way that would enhance both the performance of the bridge and the efficiency of the construction.

“We talked to a number of geofoam manufacturers,” says Qudus, ”because we wanted to make sure that we were using the geofoam product correctly. Insulfoam provided ample feedback and a detailed specification of how InsulFoam® GF can be used in this type of application.”

The construction project required a total of 2,045 cubic yards of type 15 EPS low-density geofoam blocks that were installed as void fill at the bridge abutments.

After pouring the abutment walls, the Hawkins crew installed the geofoam blocks, which not only provided easy handling, but also sped up the installation process. The use of geofoam eliminated both the need for surcharge and the settlement that is experienced with typical fill products, such as soil.

“We used geofoam for this project because we did not have enough time for both the surcharge and settlement that are typical with the application of traditional fill products,” says Qudus.

NDOR

Pacific Street Bridge, Nebraska

Hawkins’ on-site supervisor, Lance Winkler, agreed that the use of geofoam significantly reduced construction time. “With traditional fill products, we typically backfill with sand at 8-inch increments and then compact; with geofoam, we just placed the blocks in position and then backfilled the minimal area that was left with sand. The InsulFoam® GF made installation easier and more efficient.”

Installation of a drainage mat was also necessary in order to ensure that any water that might collect around the abutment would drain properly and decrease the potential for any damage that might be caused by moisture penetration. By ensuring that water drained away from the abutment, the drainage mat would also eliminate the horizontal pressure that standing water would create.

The entire construction project was completed by September 2008, a short 6 months after it was started, and the bridge was re-opened to traffic. The use of geofoam in this project not only offered enhanced labor and cost savings, but also provided the increased, long-term stability and superior performance needed for the ever-moving technological hub of Omaha, Nebraska.

 Full article (pdf)

 

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Nico Sutmoller, Insulfoam Geofoam Specialist

Nico Sutmoller, Insulfoam Geofoam Specialist

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Cold Climate Housing Research Center uses EPS Foam to Save on Costs & Energy

Written by:  David Shong, Insulfoam Architectural & Engineering Technical Specialist

CCHRC Expansion, Alaska

CCHRC Expansion, Alaska

The Cold Climate Housing Research Center, CCHRC, in Fairbanks, AK constructed an addition to their facility in the spring of 2012.  The project Engineers specified 12″ of InsulFoam GF EPS39 which has a minimum compressive resistance of 2,160 psf @ 1% strain as a sub-base and below slab insulation.  EPS39 was placed around the perimeter under the exterior wall footings and within the zones of influence of interior columns that required higher bearing capacity to withstand the axial loads of the walls,roof and snow load.

The rest of the areas that were simply supporting the 6″ floor slab used 12″ of EPS22 (1051 psf @ 1% strain).  They were originally considering only 9″ of EPS46 (2,678 psf @ 1% strain) for the entire building footprint, but were happily surprised to hear the idea of using a lower density under the floor slabs where the decreased dead loads justified a lower EPS density.

They ended up being able to install 12″ of EPS under the entire footprint for less than the original budget which provided more insulation while saving on initial costs as well as long term energy expenditures.

CCHRC Expansion, Alaska

CCHRC Expansion, Alaska

CCHRC Expansion, Alaska

CCHRC Expansion, Alaska

GeoFoam and the site development/geotechnical community is in the news!

Don’t take our word for it, we love geofoam. But others are really talking about it too. Check out the latest and greatest buzz in the industry and some great examples of how GeoFoam is used on the jobsites to save time and money.

Critical 13 Mile Stretch of US-30 uses Geofoam in Bridge Replacement and Road Expansion

McCammon, Idaho’s heavily used trucking route and bridge (circa 1940) along the U.S. 30 trucking route between Idaho and Wyoming, expands from 2 to 4 lanes to increase safety and capacity using InsulFoam GF – Geofoam.

Geofoam blocks were used to construct a new 500 foot long, 30 foot tall EPS block embankment. The new embankment supports the US-30 road expansion and its approach to the new Topaz Bridge – notably the longest span in the state of Idaho.

Project Overview:

Idaho Transportation Department’s first EPS Geofoam project was designed by Terracon Engineers and JUB Engineers of Boise. EPS was specified as a soil replacing embankment fill material due to poor foundation soils and 2 steel fish culverts that could not bear the weight of traditional soil fill.  A new three-span bridge replaced the existing bridge (from the 1940′s) crossing rail road tracks, the Pontneuf River and expanding the highway to 4 instead of 2 lanes. In all, 23,000 cubic yards of large block EPS was installed by Scarsella Brothers Inc. and supplied by Insulfoam.

US-30 provides a heavily used trucking route and bridge between Wyoming and Idaho

The Problem:

The expansion of US-30 and bridge replacement required a new fill embankment to support the new roadway and bridge approach on a very steep side slope.

The new (500 ft long) expanded bridge clears The Pontneuf River as well as the Union Pacific Railroad tracks, and required a new higher grade of both thte bridge structure and the existing roadway to support the new wide and long center spans.

As a result the new bridge approach embankment would be 45-50 feet high, too costly to be retained by conventional concrete cantilever or MSE wall, and raised concerns about global stability.

Near “Net-Zero” surcharge loads: The void in between the blocks and the native slope was filled with sand.

Further challenges to the projects design were the site conditions.  Located adjacent to the Pontneuf River, shallow bedrock and loose or soft sediments under lie the new approach embankment.

Custom fabricated “tongs” grip the large EPS blocks without damaging them.

The EPS Geofoam Fill Solution:

 To reach the new bridge’s approach embankment height of 45 feet, engineers chose a combined fill solution.  The lowest 15 feet was a small earthen embankment, while InsulFoam GF constituted the upper 30 feet. 4 1/2 feet of granular fill retained in wire gabions and an asphalt pavement section were installed directly on top o the EPS blocks to complete the full height of the new embankment.

The exposed vertical face of the EPS is eventually covered with an economical, fast to install, protective shotcrete facing.

The soft sediments underlying the site required the lower earthen embankment to settle (80 days), but the InsulFoam GF block fill required no additional surcharge time or secondary compaction by the contractor. Traffic moved on the existing roadway throughout the installation of the upper embankment, which was a key factor for the expansion to finish when weather conditions permitted.

The ultra lightweight nature of EPS allowed the total design weight of the tall embankment to be well under the bearing capacity of the poor foundation soils which aided ITD in successfully completing their first EPS Geofoam project.

The Geofoam blocks during construction

For more information about Geofoam visit www.insulfoam.com