Geofoam Overview

Expanded polystyrene (EPS) geofoam has been used as a geotechnical material since the 1960s. EPS geofoam is approximately 1% the weight of soil and less than 10% the weight of other lightweight fill alternatives. As a lightweight fill, EPS geofoam reduces the loads imposed on adjacent and underlying soils and structures.

EPS geofoam is not a general soil fill replacement material but is intended to solve engineering challenges. The use of EPS typically translates into benefits to construction schedules and lowers the overall cost of construction because it is easy to handle during construction, often without the need for special equipment, and is unaffected by occurring weather conditions. In addition, EPS geofoam can be easily cut and shaped on a project site, which further reduces jobsite challenges. EPS geofoam is available in numerous material types that can be chosen by the designer for a specific application. Its service life is comparable to other construction materials and it will retain its physical properties under engineered conditions of use.

There are numerous manufacturers and suppliers of EPS geofoam. Expanded polystyrene is created in a two-stage molded bead process. EPS geofoam is produced in blocks that can be cut into various shapes and sizes - and a range of compressive resistances - to suit specific project needs. As an engineered product, it can be produced to obtain the required compressive resistance.

EPS geofoam density, only about 1% that of soil and rock, is controlled during the manufacturing process, making it a superior, ultra-lightweight fill material that significantly reduces the stress on underlying subgrades. The lighter load can reduce settlements and can improve stability against bearing and slope failures.

Geofoam application and use

EPS geofoam is inherently multi-functional, which makes it effective to use in a wide variety of applications. It offers special advantages for construction on soft ground, slope stabilization and retaining walls. EPS geofoam has been used in road and airfield pavements and railway track systems, beneath refrigerated storage buildings, sports arenas and storage tanks to prevent ground freezing and heaving and in below-ground building segments to reduce seasonal heating and cooling requirements.

EPS geofoam enables engineers, architects, and builders to design for key geosynthetic functions and select the best combination of products to achieve project goals. With unprecedented strength and flexibility, EPS geofoam also offers innovative solutions to a range of problems, including protection from noise and vibration dampening

Road Construction Over Poor Soils

The growing need for new roads may, in many cases, require construction over soft or loose soils that are incapable of supporting additional loads. Designers must identify innovative materials and construction techniques to address the problem of building on soft soils or where sensitive existing utilities or wetlands are present while, at the same time, accelerating project schedules. EPS geofoam can be used to replace compressible soils or in place of heavy fill materials to prevent unacceptable loading on underlying soils and adjacent structures. The high compressive resistance of EPS geofoam makes it able to adequately support traffic loadings associated with secondary and interstate highways.



Road Widening

Roadways often have to be widened to reduce congestion. This situation results in additional fill being required for the roadway to be widened. This can be an expensive and time-consuming process if the soils adjacent to the existing roadway are not adequate to support the traffic loads because the resulting settlement can impact the existing roadway. In traditional construction, soil embankments are built in thin lifts, each of which must be compacted before the next lift is placed. Using EPS geofoam eliminates the need for compaction and fill testing, reduces the construction time and minimizes impact to the existing roadway and adjacent structures and/or buried utilities. The high compressive resistance of EPS geofoam makes it able to withstand the induced traffic forces without causing unacceptable loading of the underlying soils or adjacent fill.


Bridge Abutment

There are several advantages to using EPS geofoam to construct approach fills for bridge abutments. Because of its high compressive resistance, EPS geofoam can safely support highway loading without over-stressing the underlying soils. This usually results in less differential movement at the bridge/approach fill interface, which reduces the construction cost of the approach slab and its long-term maintenance. In addition, when compared to traditional embankment fills, EPS geofoam imparts significantly reduced lateral forces on abutment walls, foundations and other retaining structures, because the transmitted lateral force is proportional to the weight of the backfill. If this weight is substantially reduced, as with the case of EPS geofoam backfill, this leads to savings in the design of bridge abutment and other walls, which are no longer required to resist large horizontal static and dynamic forces.

Bridge Underfill

EPS geofoam can be used to support bridges when properly designed. EPS geofoam’s light weight adds little additional load to the underlying ground.

In cases where the existing bridge is no longer structurally capable of carrying the required traffic loads, EPS geofoam infill can help support the span and transfer the traffic load safely to the foundation or underlying soil.


Compensating Foundation

EPS geofoam can be used as a compensating foundation to reduce the load on underlying compressible soils and minimize building settlement along with potential bearing capacity problems.

Existing soil is excavated to reduce the net applied load to the soil by the new structure. If the amount of soil excavated equals the full weight or stress applied by the new structure, the foundation is called “floating” or “fully compensating.”


Culverts, Pipelines & Buried Structures

Engineering plans often call for the placement of new fill over existing underground structures that were not designed to support the increased loads.

Rather than removing or strengthening the existing underground structures, the new fill load can be reduced to a tolerable level by using EPS geofoam instead of heavier traditional fills.


Stadium and Theater Seating

EPS geofoam can be used to form tiered seating in locations such as auditoriums, movie theaters and gymnasiums.

The high compressive resistance and light weight of EPS geofoam make it well suited to both new construction and renovation projects.

For these projects, the EPS geofoam blocks are fabricated and then stacked to create the desired profile. Fascia riser screeds are attached to the front of the blocks and provide formwork for the placement of finished concrete treads. Seats, bleachers and other attachments and finishes are then added to complete the project.