Compare
Foam glass aggregate vs EPS geofoam for lightweight fill
EPS geofoam weighs 11 to 48 kg/m³ (0.7 to 3 lb/ft³) and foam glass aggregate 160 to 400 kg/m³ (10 to 25 lb/ft³), so EPS removes more load.[1] Foam glass aggregate is usually the better fit where fire, fuel spills or irregular excavations shape the design.[2][3]
Enviro-Rock at a glance
- Loose dry bulk density
- 200 kg/m³
- Angle of friction
- 39° at 65 kPa
- Thermal resistance
- R-2.4 per inch, dry
- Up to, per B-train load
- 140 m³
From the Enviro-Rock specification table and delivery trailer sheet. Sources on the product page.
Side by side
Foam glass aggregate vs EPS geofoam
| Factor | Foam glass aggregate | EPS geofoam |
|---|---|---|
| Unit weight | 160 to 400 kg/m³ (10 to 25 lb/ft³) across the material class.[1] Enviro-Rock: 200 kg/m³ (12.5 lb/ft³) loose, 240 kg/m³ (15.0 lb/ft³) at 20% compaction.[4] | 11 to 48 kg/m³ (0.7 to 3 lb/ft³).[1] Caltrans lists 13 to 32 kg/m³ (0.8 to 2 lb/ft³).[5] |
| Load reduction | 160 to 400 kg/m³, against 1,520 to 2,400 kg/m³ for mineral soils and aggregates. FHWA states that its low weight and high friction angle can reduce vertical and lateral forces by more than one-half.[1] | Lighter, so it removes the most load. On New Jersey's Wittpenn Bridge, geofoam needed less over-excavation than foam glass aggregate for that reason.[3] |
| Form and placement | Loose granular fill, spread in lifts of up to about 600 mm (24 in) under tracked equipment, or 300 mm (12 in) under a plate compactor.[6] Enviro-Rock: 300 to 600 mm loose lifts under a static roller with no vibration, or 150 to 300 mm under a plate compactor with more passes rather than more vibration; compact 10 to 20%.[7][8] | Placed as blocks. PennDOT research notes that the block shape limits its use in narrow or irregular areas.[3] |
| Fire | FHWA lists "not flammable" among its reported advantages.[1] A European Technical Assessment for one cellular glass loose fill declares reaction-to-fire Class A1.[9] | FHWA describes EPS as inherently flammable. Its natural oxygen index is 18%, below the 21% oxygen in air, so ASTM D6817 requires flame retardants, and flame-retardant EPS still melts above about 150 °C (300 °F).[1] |
| Fuel and solvent spills | In the design evaluation for New Jersey's Wittpenn Bridge, substituting foam glass aggregate for geofoam removed the gasoline-resistant geomembrane and the 100 mm (4 in) concrete slab, though the aggregate base above had to be thickened.[3] TAC research notes that, being glass, it does not degrade in the chemicals common in a pavement.[10] | Vulnerable to petroleum solvents.[1] Michigan DOT notes it dissolves in gasoline or diesel spills, so it needs a geomembrane and usually a concrete cap.[2] |
| Buoyancy | Buoyant. Illinois Tollway testing found a net uplift of about 2.4 kN/m³ (15 lb/ft³) when submerged, and its design guide places the fill above groundwater and the 500-year flood level, or ballasts it.[11] | Buoyant.[1] Michigan DOT notes it can float.[2] |
| Insulation | Insulates as it fills. In the first, mild winter of a Quebec field trial, 150 mm of foam glass aggregate insulated a pavement about as well as 50 mm of XPS board.[10] | Polystyrene insulates more per millimetre. A Norwegian study cited by TAC used foam glass layers 4 to 5 times thicker than polystyrene panels for equal thermal performance.[10] |
Where foam glass aggregate fits
When foam glass aggregate is the better choice
Foam glass aggregate is the better choice where fire, fuel spills or the protection layers around the fill drive the design. FHWA lists it as not flammable[1], and TAC research notes it does not degrade in the chemicals common in a pavement.[10] In the Wittpenn Bridge design evaluation, substituting it for geofoam removed the gasoline-resistant geomembrane and the 100 mm concrete slab, though the aggregate base above had to be thicker.[3]
It also suits narrow or irregular excavations, where geofoam blocks are hard to fit, because it is spread and compacted like other aggregate.[3][6] The compacted layer is free-draining and adds insulation.[11][10]
Both materials float, so either one needs an uplift check where groundwater or flooding can reach it.[1][11] At Jim Lorimer Park in Burnaby, where the site floods seasonally, the Enviro-Rock design anchored the fill against uplift.[12]
Where EPS geofoam fits
When EPS geofoam may be the better choice
- The lowest possible unit weight governs, for example over very soft ground or on a structure with a tight load limit. At 11 to 48 kg/m³, EPS removes more load than any foam glass aggregate.[1]
- Excavation depth has to be kept to a minimum. Because geofoam is lighter, it needed less over-excavation than foam glass aggregate on the Wittpenn Bridge.[3]
- The fill zone is a regular shape that blocks fit well. PennDOT's concern with block shape applies to narrow or irregular areas.[3]
- Insulation has to fit in a thin layer. Polystyrene panels match the thermal performance of a foam glass layer 4 to 5 times thicker.[10]
- Placement speed or lateral pressure governs. Blocks go in quickly without heavy compaction equipment, and Michigan DOT notes very low to virtually no lateral earth pressure when they sit far enough behind an abutment.[2][1]
Questions
Common questions
Is foam glass aggregate a good alternative to geofoam?
Yes, where fire, fuel spills, irregular shapes or drainage matter more than the lowest possible unit weight. EPS weighs 11 to 48 kg/m³ against 160 to 400 kg/m³ for foam glass aggregate, so EPS still removes more load.[1]
What are the disadvantages of geofoam?
FHWA notes that EPS geofoam is inherently flammable, vulnerable to petroleum solvents and buoyant.[1] Michigan DOT adds that it dissolves in gasoline or diesel spills and usually needs a geomembrane and a concrete cap.[2]
Does geofoam float?
Yes. FHWA lists EPS geofoam as buoyant, and Michigan DOT notes it can float.[1][2] Foam glass aggregate is buoyant too, so designs keep it above groundwater and flood levels or hold it down with cover material.[11]
How heavy is geofoam compared with foam glass aggregate?
EPS geofoam weighs 11 to 48 kg/m³ (0.7 to 3 lb/ft³), and foam glass aggregate 160 to 400 kg/m³ (10 to 25 lb/ft³).[1] Enviro-Rock weighs 200 kg/m³ loose and 240 kg/m³ at 20% compaction.[4]
Does foam glass aggregate crush when it is compacted?
It can if it is over-compacted, and Maine DOT's provision warns against over-compaction and particle crushing.[13] Enviro-Rock goes down in 300 to 600 mm loose lifts under a static roller with no vibration, or 150 to 300 mm under a plate compactor with more passes rather than more vibration, and is compacted 10 to 20%.[7][8]
Sources
- [1] Alternative Backfills for Highway Applications: State of the Practice (FHWA-HRT-23-110), Federal Highway Administration, 2024
- [2] How Low Can You Go: Various Materials Used by MDOT to Reduce Lateral Earth Loading Pressures, Michigan DOT, 2025
- [3] Lightweight and Sustainable Materials in Engineered Fills (FHWA-PA-2021-011), PennDOT and Temple University, 2021
- [4] Enviro-Rock civil infrastructure brochure (metric), specification table, Enviro-Corp Recycling
- [5] Ground Modification, Geotechnical Manual, Caltrans, 2026
- [6] Guidelines for Using Lightweight Fills in Transportation Infrastructure Applications, Texas DOT and University of Texas at Austin, 2025
- [7] Enviro-Rock installation guide, Enviro-Corp Recycling
- [8] Enviro-Rock compaction equipment sheet, Enviro-Corp Recycling
- [9] European Technical Assessment ETA-13/0549, cellular glass loose fill, DIBt, Germany, 2020
- [10] Innovative materials for road insulation in cold climates: foam glass aggregates, Transportation Association of Canada, 2016
- [11] Applications for Foamed Glass Lightweight Aggregate, final report, Illinois Tollway Research Program, Washington State University et al., 2025
- [12] Case study: Jim Lorimer Park playground, Burnaby, Enviro-Corp Recycling
- [13] Special Provision Section 203, Ultra-Lightweight Foamed Glass Aggregate, Maine DOT, 2025
Get a price and a delivery window.
Tell us the application, the volume and where it is going. A real person replies with pricing and a delivery window.