Geofoam
Encyclopedia
Geofoam is expanded polystyrene
(EPS) or extruded polystyrene (XPS) manufactured into large lightweight blocks. The blocks vary in size but are often 2 m x 0.75 m x 0.75 m. 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, the major ones being as lightweight fill, green roof
fill, compressible inclusions, thermal insulation
, and (when appropriately formed) drainage
.
The area of geofoam can nicely segue into geocombs, previously called ultralight cellular structures which Horvath defines 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 of the order of 25 mm across. The overall cross-section of the assemblage of bundled tubes resembles a honeycomb that gives rise to its name. Presently, only rigid polymers (polypropylene
and PVC
) have also been used as geocomb material.
Due to the success of the Oslo Geofoam project, the first International Geofoam Conference was held in Oslo, Norway in 1985 so engineers could exchange knowledge, research results, share new applications, and discuss case histories. Since then, two more conferences were held in Tokyo, Japan and Salt Lake City, USA 1996 and 2001, respectively. The next conference is planned for June 2011 in Lillestrom, Norway.
Between 1985 to 1987, Japan used over 1.3 million cubic meters of Geofoam in 2,000 projects. Testing and use of Geofoam in these projects demonstrated the potential advantages of Geofoam as a light-weight 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 was in 1989 on Highway 160 between Durango 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 in this project versus conventional restoration resulted in a cost savings of 500%..
The largest Geofoam project in the United States lasted from 1997 to 2001 on Interstate 15 in Utah. Geofoam was chosen to minimize that amount of utilities that would need to be relocated or remodeled for the project. A total of 3.53 million cubic feet of Geofoam was used, and approximately $450,000 was saved by not needing to relocate utility poles. Geofoam was also used in embankments and bridge abutments for base stability.
. Geofoam is up to 50 times lighter that other traditional fills with similar compressive strengths. This allows Geofoam to maximize the available right-of-way on an embankment. Geofoam’s light weight accompanied by its ease to install reduces construction time and labor costs.
without being affected. Maintenance costs associated with Geofoam embankments are significantly lower when compared to embankments using natural soil.
or abutment
. It is important to install a draining system under the Geofoam to insure that you don’t have problems with built up hydrostatic pressure or buoyancy
.
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 insulating effects.
Polystyrene
Polystyrene ) also known as Thermocole, abbreviated following ISO Standard PS, is an aromatic polymer made from the monomer styrene, a liquid hydrocarbon that is manufactured from petroleum by the chemical industry...
(EPS) or extruded polystyrene (XPS) manufactured into large lightweight blocks. The blocks vary in size but are often 2 m x 0.75 m x 0.75 m. The primary function of geofoam is to provide a lightweight void fill below a highway, bridge approach, embankment
Embankment (transportation)
To keep a road or railway line straight or flat, and where the comparative cost or practicality of alternate solutions is prohibitive, the land over which the road or rail line will travel is built up to form an embankment. An embankment is therefore in some sense the opposite of a cutting, and...
or parking lot. EPS Geofoam minimizes settlement on underground utilities. Geofoam is also used in much broader applications, the major ones being as lightweight fill, green roof
Green roof
A green 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 drainage and irrigation systems...
fill, compressible inclusions, thermal insulation
Thermal insulation
Thermal insulation is the reduction of the effects of the various processes of heat transfer between objects in thermal contact or in range of radiative influence. Heat transfer is the transfer of thermal energy between objects of differing temperature...
, and (when appropriately formed) drainage
Drainage
Drainage is the natural or artificial removal of surface and sub-surface water from an area. Many agricultural soils need drainage to improve production or to manage water supplies.-Early history:...
.
The area of geofoam can nicely segue into geocombs, previously called ultralight cellular structures which Horvath defines 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 of the order of 25 mm across. The overall cross-section of the assemblage of bundled tubes resembles a honeycomb that gives rise to its name. Presently, only rigid polymers (polypropylene
Polypropylene
Polypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
and PVC
PVC
Polyvinyl chloride is a plastic.PVC may also refer to:*Param Vir Chakra, India's highest military honor*Peripheral venous catheter, a small, flexible tube placed into a peripheral vein in order to administer medication or fluids...
) have also been used as geocomb material.
History
The first use of EPS Geofoam was in Olso, 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.Due to the success of the Oslo Geofoam project, the first International Geofoam Conference was held in Oslo, Norway in 1985 so engineers could exchange knowledge, research results, share new applications, and discuss case histories. Since then, two more conferences were held in Tokyo, Japan and Salt Lake City, USA 1996 and 2001, respectively. The next conference is planned for June 2011 in Lillestrom, Norway.
Between 1985 to 1987, Japan used over 1.3 million cubic meters of Geofoam in 2,000 projects. Testing and use of Geofoam in these projects demonstrated the potential advantages of Geofoam as a light-weight 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 was in 1989 on Highway 160 between Durango 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 in this project versus conventional restoration resulted in a cost savings of 500%..
The largest Geofoam project in the United States lasted from 1997 to 2001 on Interstate 15 in Utah. Geofoam was chosen to minimize that amount of utilities that would need to be relocated or remodeled for the project. A total of 3.53 million cubic feet of Geofoam was used, and approximately $450,000 was saved by not needing to relocate utility poles. Geofoam was also used in embankments and bridge abutments for base stability.
Slope Stabilization
Slope Stabilization is the use of Geofoam in order to reduce the mass and gravitational force in an area that may be subject to failure, such as a landslideLandslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
. Geofoam is up to 50 times lighter that other traditional fills with similar compressive strengths. This allows Geofoam to maximize the available right-of-way on an embankment. Geofoam’s light weight accompanied by its ease to install reduces construction time and labor costs.
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 settlementSettlement (structural)
Settlement in a structure refers to the distortion or disruption of parts of a building due to either; unequal compression of its foundations, shrinkage such as that which occurs in timber framed buildings as the frame adjusts its moisture content, or by undue loads being applied to the building...
without being affected. Maintenance costs associated with Geofoam embankments are significantly lower when compared to embankments using natural soil.
Retaining Structures
Retaining Structures using Geofoam have a reduction in lateral pressure as well as prevent settlement and improve water proofing. Geofoam light weight will reduce the lateral force on a retaining wallRetaining wall
Retaining walls are built in order to hold back earth which would otherwise move downwards. Their purpose is to stabilize slopes and provide useful areas at different elevations, e.g...
or abutment
Abutment
An abutment is, generally, the point where two structures or objects meet. This word comes from the verb abut, which means adjoin or having common boundary. An abutment is an engineering term that describes a structure located at the ends of a bridge, where the bridge slab adjoins the approaching...
. It is important to install a draining system under the Geofoam to insure that you don’t have problems with built up hydrostatic pressure or buoyancy
Buoyancy
In physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
.
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 heaveFrost heaving
Frost heaving results from ice forming beneath the surface of soil during freezing conditions in the atmosphere. The ice grows in the direction of heat loss , starting at the freezing front or boundary in the soil...
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 insulating effects.
Advantages
Advantages of using Geofoam include:- Low densityDensityThe mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
/ high strengthStrength of materialsIn materials science, the strength of a material is its ability to withstand an applied stress without failure. The applied stress may be tensile, compressive, or shear. Strength of materials is a subject which deals with loads, deformations and the forces acting on a material. A load applied to a...
: 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 breakdown, 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.
- Limited labor required for construction: Geofoam can be installed by hand using simple hand tools. This eliminates the investment and operating cost of heavy machinery.
- Cuts down on construction time: Geofoam is quick to install and can be installed during any type of weather, day or night, 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 buoyancyBuoyancyIn physics, buoyancy is a force exerted by a fluid that opposes an object's weight. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the...
can result in a dangerous uplift force.
- Susceptible to insect damage: Geofoam should be treated to resist insect infestation. If it is not, insects such as ants can burrow into the Geofoam, weakening the material.
Specifications
| Physical Properties of EPS Geofoam | |||||
|---|---|---|---|---|---|
| TYPE - ASTM D6817 | EPS12 | EPS15 | EPS19 | EPS22 | EPS29 |
| Density, min. kg/m3 | 11.2 | 14.4 | 18.4 | 21.6 | 28.8 |
| Compressive Resistance @ 1% deformation, min., kPa | 15 | 25 | 40 | 50 | 75 |
| Flexural Strength min., kPa | 69 | 172 | 207 | 276 | 345 |
| Water Absorption by total immersion, max., volume % | 4.0 | 4.0 | 3.0 | 3.0 | 2.0 |
| Oxygen Index, min., volume % | 24.0 | 24.0 | 24.0 | 24.0 | 24.0 |
| Buoyancy Force kg/m3 | 952 | 955 | 958 | 961 | 969 |
| Physical Properties of EPS Geofoam | |||||
|---|---|---|---|---|---|
| TYPE - ASTM D6817 | EPS12 | EPS15 | EPS19 | EPS22 | EPS29 |
| Density, min. lb/ft3 | 0.70 | 0.90 | 1.15 | 1.35 | 1.80 |
| Compressive Resistance @ 1% deformation, min., psi | 2.2 | 3.6 | 5.8 | 7.3 | 10.9 |
| Flexural Strength min., psi | 10.0 | 25.0 | 30.0 | 40.0 | 50.0 |
| Water Absorption by total immersion, max., volume % | 4.0 | 4.0 | 3.0 | 3.0 | 2.0 |
| Oxygen Index, min., volume % | 24.0 | 24.0 | 24.0 | 24.0 | 24.0 |
| Buoyancy Force lb/ft3 | 59.4 | 59.6 | 59.8 | 60.0 | 60.5 |
External links
- Insulfoam - Geofoam Manufacturer
- ACH Foam Technologies - Geofoam Manufacturer
- Atlas EPS - Geofoam Manufacturer
- EPS Molders Association
- Foam-Control EPS - Nations Largest Manufacturer