What is geofoam?
Geofoam is an engineered structural fill used in geotechnical application. Its purpose can be weight reduction, soil or foundation stabilization, reducing lateral and/or horizontal loads on retaining walls, buried utilities and structures, and many others. In some cases it provides more than one benefit. Elevation Geofoam is the Atlas EPS brand of geofoam which has 3rd party certification for physical properties including compressive resistance and a 20 year warranty – the best in the business.
What is the primary difference between EPS and XPS in geofoam applications?
EPS is expanded polystyrene and it is predominately the material being referenced when the term geofoam is used. Due to the unique molding process of EPS it can be produced in block form rather than sheets. Typical EPS blocks are between 8-40” thick and 4-16’ long. XPS is extruded polystyrene and due to it’s extrusion process it typically has a thickness limitation of 4”.
What types of projects use geofoam?
• Slope Stabilization
• Soil Stabilization
• Bridge Abutments
• Theater “Stadium” Seating
• Retaining Structures
• Utility Protection
• Pavement Insulation
• Shallow Foundations
Is the grade of geofoam important for my project?
Determining the correct grade of material ensures project success and minimizes costs. Compressive resistance is the primary factor in determining the grade of material required for a project. In a geofoam application it should be calculated at 1% deformation as referenced in ASTM D6817. The elastic stress limit of EPS and XPS is between 1-2%. When you exceed the stress limit, permanent deformation will occur and the results could be cracks and or buckling of the surface material and a potential project failure. Compressive resistance for Elevation geofoam ranges from 2.2 to 18.6 psi or 316-2678 psf.
How much geofoam do I need?
UNIT CONVERSION CHART
• 1 cubic meter = 423.776 board feet
• 1 cubic yard = 0.765 cubic meters
• 1 cubic yard = 324.000 board feet
• 1 cubic yard = 27 cubic feet
• 1 board foot = 144 cubic inches
• 1 kilogram = 2.204 pounds
• 1 pound/sf = 0.00694 psi
• 1 psi = 144 pound/sf
• 1 psi = 6.895 kPa
• 1 pound/cubic foot = 16.02kg/cubic meter
• 1 kilogram/cubic meter = 0.06242 pounds/cubic meter
How much does geofoam cost?
The geofoam value chain, and therefore its price, is petrochemical-based: that means its cost is correlated to the cost of oil. Below is an example of approximate cost of geofoam compared to cost of oil.
What chemicals are compatible with geofoam?
COMPATIBILTY OF GEOFOAM WITH COMMON CHEMICALS
Inorganic Acids (Muriatic, Sulfuric, Boric Acid) – Excellent
Organic Acids (Carbolic, Citric, Acetic Acid) – Good
Bases (Sodium Hydroxide, Potassium Hydroxide, Ammonia) – Excellent
Alcohols (Methanol, Ethanol, Isopropyl Alcohol) – Good
Beer, Tea, Coffee, Carbonated Soda, Water, Fruit Juice – Excellent
Household Liquid Spray Insecticides (non-aqueous) – Poor
Cement – Excellent
MEK, Methylene Chloride, Acetone – Poor
Antifreeze (Ethylene Glycol –Green, Propylene Glycol – Orange) – Excellent
Hydrocarbons (Hexane, Gasoline, Diesel, Kerosene) – Poor
Mineral Oil – Excellent
Other Oils (Corn, Motor, Palm, Coconut Oil) – Good
Agricultural (Manure, Food, Urine, Soil, Fertilizer) – Excellent
Formaldehyde, Turpentine, Chloroform, Naphtha – Poor
Salts (Ammonium, Ferrous, Sodium Chloride, Sulfur) – Excellent
MDI-based Adhesives (Gorilla Glue, Fast-Tac, Dow Great Stuff) – Good
Bleach, Detergents, Borax – Excellent
Cured Mastic, Construction Adhesive, Hardened Asphalt – Good
Excellent = No degradation, no effect from exposure
Good = Some effect from exposure, but not significant for product performance
Poor = Significant degradation affecting performance, up to completely dissolving product
This table is a guide only — consult Atlas Technical Services for specific chemical design questions.
Connector plates or adhesive?
Connector plates are 4” x 4” galvanized steel plates used to prevent the geofoam blocks from sliding laterally during the backfill stage. There is enough surface friction to prevent blocks from shifting on their own but the added pressure exerted during backfill requires the blocks to be held in place with geofoam connector plates. Adhesives may be used to accomplish the same objective but is more costly due to increased labor.
What is a geomembrane?
Geomembranes are used on projects where there is potential for the geofoam to come into contact with petroleum products or other hydrocarbons. Whether the contamination source is from above, like a road, or below in a contaminated soil environment, the geomembranes role is to separate the foam from petroleum vapors as the foam is susceptible to hydrocarbons. (see chemical compatibility)
Do I need a geomembrane for my project?
Any project where the geofoam has potential to come into contact with hydrocarbons should have a geomembrane. If the protection is strictly from above then just the top and sides require protection, when the protection is from existing soil contamination as well as above, the foam must be fully enveloped in the geomembrane. Seams must be heat welded to provide adequate protection.
Where can I purchase a geomembrane?
Geomembranes are available in various materials similar to roofing and waterproofing membranes. Be aware of the chemical compatibility chart as geomembranes are used for non geofoam applications as well and not all geomembranes are approved for use with geofoam. There are just a few manufacturers of geomembranes but several distributors: Cooley Group, Raven Industries, Geo-Composites, Barber Webb, and White Cap, to name a few.