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Foam glass aggregate vs lightweight cellular concrete
Foam glass aggregate is spread and compacted with ordinary earthworks equipment and drains freely.[1][2] Lightweight cellular concrete is placed by a specialty contractor in lifts that must cure.[3][4]
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 lightweight cellular concrete
| Factor | Foam glass aggregate | Lightweight cellular concrete |
|---|---|---|
| Unit weight | 160 to 400 kg/m³ (10 to 25 lb/ft³) across the material class.[5] Enviro-Rock: 200 kg/m³ (12.5 lb/ft³) loose, 240 kg/m³ (15.0 lb/ft³) at 20% compaction.[6] | 320 to 960 kg/m³ (20 to 60 lb/ft³).[5] |
| Typical design weight | PennDOT practice and the Illinois Tollway design guide use 376 kg/m³ (23.5 lb/ft³), moist and compacted in place.[2] | Michigan DOT's Class II cellular concrete is 480 kg/m³ (30 lb/ft³).[3] |
| Placement | Spread in lifts of up to about 600 mm (24 in) under tracked equipment, or 300 mm (12 in) under a plate compactor.[1] 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] | Michigan DOT notes it needs a specialty contractor and places it in lifts of no more than about 600 mm (2 ft) to limit heat of hydration; PennDOT research notes curing time between lifts can lengthen the schedule.[3][4] |
| Pressure on walls | FHWA states that low weight and a high friction angle can reduce vertical and lateral forces by more than one-half.[5] Enviro-Rock's friction angle is 39° at 65 kPa.[6] | Michigan DOT designs for a uniform final lateral pressure of about 1.4 kPa (30 lb/ft²) from cellular concrete.[3] |
| Environmental impact | Lower than cellular concrete on every cradle-to-gate indicator compared, including global warming potential, in Illinois Tollway research. The foam glass figures came from European product declarations, some for cellular glass boards, and the cellular concrete figures from published studies.[2] | Higher on each of those indicators in the same comparison.[2] |
| Cost | In Illinois Tollway research, foam glass aggregate shipped 800 miles cost $169 per cubic yard in place; with a plant 10 miles away the same estimate fell to $135.[2] | About $150 per cubic yard in place, from low-quantity bids, in the same research.[2] |
Where foam glass aggregate fits
When foam glass aggregate is the better choice
Foam glass aggregate is the better fit where the schedule, crew or site favour ordinary earthworks. It is spread and compacted with tracked equipment or plate compactors, while cellular concrete needs a specialty contractor and lifts that cure.[1][3][4]
It also wins where environmental impact is weighed. Illinois Tollway research found it lower than cellular concrete on every cradle-to-gate indicator compared, using European product declarations, some for cellular glass boards, rather than Enviro-Rock data.[2]
On cost, the same research found foam glass aggregate hauled 800 miles more expensive than cellular concrete, and the estimate fell below it with a plant 10 miles away.[2] Shipping distance is a main driver of its cost[9], and Enviro-Rock is delivered from its BC facilities, including a stockpile in the Fraser Valley[10], in trailer loads of up to 140 m³.[11]
Where lightweight cellular concrete fits
When lightweight cellular concrete may be the better choice
- The lowest installed cost governs and the haul for foam glass aggregate is long. Cellular concrete cost less than foam glass aggregate hauled 800 miles in the Illinois Tollway research.[2]
- The wall needs a very low, uniform lateral pressure. Michigan DOT designs for a uniform final pressure of about 1.4 kPa (30 lb/ft²) from cellular concrete.[3]
- The owner works from guidance that covers cellular concrete but not foam glass aggregate. Caltrans's ground modification manual, for example, lists cellular concrete and does not list foam glass aggregate.[12]
- The fill has to reach confined or irregular voids, or surround utilities, without compaction. Cellular concrete is self-leveling and self-compacting and can be pumped long distances, so it reaches places a granular fill cannot.[4][12][3]
Questions
Common questions
Is foam glass aggregate cheaper than cellular concrete?
Not over a long haul. In Illinois Tollway research, foam glass aggregate shipped 800 miles cost $169 per cubic yard in place against $150 for cellular concrete, and with a plant 10 miles away the estimate fell to $135.[2] Enviro-Rock is delivered from its BC facilities, including a stockpile in the Fraser Valley.[10]
What is lightweight cellular concrete used for?
It is used as lightweight fill and backfill. FHWA lists it among alternative highway backfills at 320 to 960 kg/m³, and Michigan DOT uses it to reduce lateral earth pressure on walls.[5][3]
What are the disadvantages of lightweight cellular concrete?
Michigan DOT notes that it needs a specialty contractor and lifts of no more than about 600 mm (2 ft) to limit heat of hydration, and PennDOT research notes curing time between lifts.[3][4] Illinois Tollway research also found it higher than foam glass aggregate on every cradle-to-gate environmental indicator compared.[2]
Which has the lower environmental impact?
In Illinois Tollway research, foam glass aggregate was lower than cellular concrete on every cradle-to-gate indicator compared.[2] That comparison used European foam glass product declarations, some for cellular glass boards, and published studies for cellular concrete, not Enviro-Rock data.
Can foam glass aggregate be placed with ordinary equipment?
Yes. It goes down in lifts of up to about 600 mm under tracked equipment, or 300 mm under a plate compactor.[1] Enviro-Rock calls for 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, compacted 10 to 20% to avoid breaking down particles.[7][8]
Sources
- [1] Guidelines for Using Lightweight Fills in Transportation Infrastructure Applications, Texas DOT and University of Texas at Austin, 2025
- [2] Applications for Foamed Glass Lightweight Aggregate, final report, Illinois Tollway Research Program, Washington State University et al., 2025
- [3] How Low Can You Go: Various Materials Used by MDOT to Reduce Lateral Earth Loading Pressures, Michigan DOT, 2025
- [4] Lightweight and Sustainable Materials in Engineered Fills (FHWA-PA-2021-011), PennDOT and Temple University, 2021
- [5] Alternative Backfills for Highway Applications: State of the Practice (FHWA-HRT-23-110), Federal Highway Administration, 2024
- [6] Enviro-Rock civil infrastructure brochure (metric), specification table, Enviro-Corp Recycling
- [7] Enviro-Rock installation guide, Enviro-Corp Recycling
- [8] Enviro-Rock compaction equipment sheet, Enviro-Corp Recycling
- [9] Applications for Foamed Glass Lightweight Aggregate, research summary, Washington State Transportation Center (TRAC), 2025
- [10] Delivering Enviro-Rock to downtown Vancouver from the Fraser Valley stockpile (video), Enviro-Corp Recycling
- [11] Enviro-Rock delivery trailer overview, Enviro-Corp Recycling
- [12] Ground Modification, Geotechnical Manual, Caltrans, 2026
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