Geofoam is expanded polystyrene (EPS) or

extruded polystyrene Polystyrene (PS) is a synthetic polymer made from monomers of the aromatic hydrocarbon styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and brittle. It is an inexpensive resin per unit weight. It i ...

(XPS) manufactured into large lightweight blocks. The blocks vary in size but are often . The primary function of geofoam is to provide a lightweight void fill below a highway, bridge approach, embankment or parking lot. EPS Geofoam minimizes settlement on underground utilities. Geofoam is also used in much broader applications, including lightweight fill,

green roof A green roof or living roof is a roof of a building that is partially or completely covered with vegetation and a growing medium, planted over a waterproofing membrane. It may also include additional layers such as a root barrier and drainag ...

fill, compressible inclusions,

thermal insulation Thermal insulation is the reduction of heat transfer (i.e., the transfer of thermal energy between objects of differing temperature) between objects in thermal contact or in range of radiative influence. Thermal insulation can be achieved with ...

, and (when appropriately formed)

drainage Drainage is the natural or artificial removal of a surface's water and sub-surface water from an area with excess of water. The internal drainage of most agricultural soils is good enough to prevent severe waterlogging (anaerobic conditio ...

. Geofoam shares principles with geocombs (previously called ultralight cellular structures) which has been defined as "any manufactured material created by an extrusion process that results in a final product that consists of numerous open-ended tubes that are glued, bonded, fused or otherwise bundled together." The cross-sectional geometry of an individual tube typically has a simple geometric shape (circle, ellipse, hexagon, octagon, etc.) and is on the order of across. The overall cross-section of the assemblage of bundled tubes resembles a honeycomb that gives it its name. Presently, only rigid

polymer A polymer (; Greek ''poly-'', "many" + '' -mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and ...

s (

polypropylene Polypropylene (PP), also known as polypropene, is a thermoplastic polymer used in a wide variety of applications. It is produced via chain-growth polymerization from the monomer propylene. Polypropylene belongs to the group of polyolefins an ...

and PVC) have been used as geocomb material.

History

The first use of EPS Geofoam was in

Oslo Oslo ( , , or ; sma, Oslove) is the capital and most populous city of Norway. It constitutes both a county and a municipality. The municipality of Oslo had a population of in 2022, while the city's greater urban area had a population of ...

, Norway in 1972. Geofoam was used in the embankments around the Flom Bridge in an effort to reduce settlements. Prior to installing geofoam, this area experienced 20–30 centimeters of settlement annually causing extreme roadway damage.Elragi, Ahmed Fouad
Selected Engineering Properties and Applications of EPS Geofoam – Introduction
Softoria Group. 2006. Web. 18 Nov. 2010. Due to the success of the Oslo geofoam project, the first International Geofoam Conference was held in Oslo, Norway in 1985 for engineers to exchange knowledge, research results, share new applications, and discuss case histories. Since then, two more conferences were held in

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and List of cities in Japan, largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, ...

, Japan and

Salt Lake City Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...

, US, in 1996 and 2001, respectively. The most recent conference was held in June 2011 in Lillestrom, Norway. Between 1985 and 1987, Japan used over of geofoam in 2,000 projects. Testing and use of geofoam in these projects demonstrated the potential advantages of geofoam as a lightweight fill. For example, Geofoam was placed beneath runways in Japanese airports, proving the material can sustain heavy and repeated pressure. Geofoam was first used in the United States in 1989 on Highway 160 between

Durango Durango (), officially named Estado Libre y Soberano de Durango ( en, Free and Sovereign State of Durango; Tepehuán: ''Korian''; Nahuatl: ''Tepēhuahcān''), is one of the 31 states which make up the 32 Federal Entities of Mexico, situated i ...

and Mancos, Colorado. An increase in rainfall caused a landslide, destroying part of the highway. Geofoam was used to create highway side slope stabilization to prevent any similar issues. The use of geofoam versus conventional restoration resulted in an 84% reduction to the total cost of the project.Geofoam Research Center
Syracuse University Syracuse, 2000. Web. 18 Nov. 2010. The largest geofoam project in the United States took place from 1997 to 2001 on

Interstate 15 Interstate 15 (I-15) is a major Interstate Highway in the western United States, running through Southern California and the Intermountain West. I-15 begins near the Mexican border in San Diego County and stretches north to Alberta, Cana ...

in Salt Lake City, Utah. Geofoam was chosen to minimize that amount of utilities that would need to be relocated or remodeled for the project. A total of of geofoam was used, and approximately $450,000 was saved by eliminating the need to relocate utility poles. Geofoam was also used in embankments and bridge abutments for base stability. Subsequently, because of the success of usage of geofoam for the I-15 Reconstruction Project, the Utah Transit Authority has used geofoam embankment for its light rail (i.e., TRAX) and commuter rail lines (i.e., FrontRunner). From 2009 to 2012, a Vaudreuil-based expanded polymer manufacturing company provided over of geofoam for a new segment of highway 30 in the province of

Quebec Quebec ( ; )According to the Government of Canada, Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is ...

, in the

Montreal Montreal ( ; officially Montréal, ) is the second-most populous city in Canada and most populous city in the Canadian province of Quebec. Founded in 1642 as '' Ville-Marie'', or "City of Mary", it is named after Mount Royal, the triple- ...

area, making it the largest geofoam project in North America to date. Since 2016, Geofoam is extensively used in the construction of the new elevated highway 15 and Turcot interchange in Montreal.

Applications

A brief summary of applications can be found at:

Slope stabilization

Slope stabilization is the use of geofoam in order to reduce the mass and

gravitational force In physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...

in an area that may be subject to failure, such as a

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated slope failures, mudflows, and debris flows. Landslides occur in a variety of environments, ...

. Geofoam is up to 50 times lighter than other traditional fills with similar compressive strengths. This allows geofoam to maximize the available

right-of-way Right of way is the legal right, established by grant from a landowner or long usage (i.e. by prescription), to pass along a specific route through property belonging to another. A similar ''right of access'' also exists on land held by a gov ...

on an embankment. Geofoam's light weight and ease of installation reduces construction time and labor costs. Geofoam bridge overpass

Embankments

Embankments using geofoam allow for a great reduction in necessary side slopes compared to typical fills. Reducing the side slope of the embankment can increase the usable space on either side. These embankments can also be built upon soils affected by differential settlement without being affected. Maintenance costs associated with geofoam embankments are significantly lower when compared to embankments using natural soil.

Reduced digging

Some weak and soft soil cannot support the weight of the desired structure; an overpass bridge on the nearby picture. If it was built out of traditional earthwork filling, it would have been too heavy and deform the weak soil underneath and damage the bridge. To reduce costs by not digging into the bedrock, geofoam is used for the interior filling of the bridge

Retaining structures

Using geofoam for retaining structures provides a reduction in lateral pressure as well as preventing settlement and improving waterproofing. Geofoam's light weight will reduce the lateral force on a

retaining wall Retaining walls are relatively rigid walls used for supporting soil laterally so that it can be retained at different levels on the two sides. Retaining walls are structures designed to restrain soil to a slope that it would not naturally keep to ...

abutment An abutment is the substructure at the ends of a bridge span or dam supporting its superstructure. Single-span bridges have abutments at each end which provide vertical and lateral support for the span, as well as acting as retaining wall ...

. It is important to install a draining system under the geofoam to prevent problems with built-up

hydrostatic pressure Fluid statics or hydrostatics is the branch of fluid mechanics that studies the condition of the equilibrium of a floating body and submerged body " fluids at hydrostatic equilibrium and the pressure in a fluid, or exerted by a fluid, on an i ...

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

Utility protection

Utility Protection is possible by using geofoam to reduce the vertical stresses on pipes and other sensitive utilities. Reducing the weight on top of a utility by using geofoam instead of a typical soil prevents utilities from potential issues, such as collapses.

Pavement insulation

Pavement insulation is the use of geofoam under pavement where pavement thickness can be controlled by frost heave conditions. Using geofoam as a sub-grade insulation element will decrease this differential thickness. Geofoam is 98% air by volume, making it an effective thermal insulator. Proper installation of geofoam is especially important as gaps between geofoam blocks will work against geofoam's insulating effects.

Advantages

Advantages of using geofoam include: * Low

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematicall ...

/high strength: Geofoam is 1% to 2% the density of soil with equal strength. * Predictable behavior: Geofoam allows engineers to be much more specific in the design criteria. This is very different than other lightweight fillers, such as soil, that can be very variable in composition. * Inert: Geofoam will not break down, so it will not spread into surrounding soils. This means that geofoam will not pollute the surrounding soil. Geofoam can also be dug up and reused. * Decreases construction time: Geofoam is quick to install and can be installed during any type of weather, resulting in faster installation time.

Disadvantages

Disadvantages of using geofoam include: * Fire hazards: Untreated geofoam is a fire hazard. * Vulnerable to petroleum solvents: If geofoam comes in contact with a petroleum solvent, it will immediately turn into a glue-type substance, making it unable to support any load. * Buoyancy: Forces developed because of

can result in a dangerous uplift force. Cars were crushed against the ceiling after floodwaters raised polystyrene below the floor of a car park in

Crayford Crayford is a town and electoral ward in South East London, England, within the London Borough of Bexley. It lies east of Bexleyheath and north west of Dartford. Crayford was in the historic county of Kent until 1965. The settlement deve ...

on 9 October 2016. * Susceptible to insect damage: Geofoam can be treated to resist insect infestation. When geofoam is used for insulating buildings where wood is present damage to the geofoam can be limited by use of insect treatment. On the other hand, in traditional lightweight fill for road construction no known evidence of insect damage has been documented.

Specifications

Block Geofoam – Meeting Project Specifications
Espmolders.org. EPS Molders Association. Web. 11 Nov. 2010.

References

External links

{{commons category, Geofoam Building materials Building insulation materials Insulators Organic polymers Plastics applications