C578 Type I GEO15
Grade
GEO15 = ePS15 geofoam block
Same nominal density supplied as large lightweight-fill blocks specified by strain-level compressive resistance rather than by C578 board properties.
Values for the GEO15 condition
Other C578 Type I grades and fills
C578 Type I is listed in 5 conditions; see the grade overview at C578 Type I.
Compare all 5 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
GEO15This page EPS15 geofoam block | Same nominal density supplied as large lightweight-fill blocks specified by strain-level compressive resistance rather than by C578 board properties. | — | 0.1 | 2 | — |
Non-flame-retardant packaging EPS | Cheapest bead for cushioning, fish boxes and void fill where no building fire requirement applies; does not satisfy the C578 LOI clause. | — | 0.13 | 2 | — |
Antistatic / static-dissipative EPS packaging | Choose for electronics and PCB packaging where surface charge must bleed off; antistatic agent is coated or compounded into the bead. | — | 0.13 | 2 | — |
Graphite-enhanced grey EPS | Pick when the same thickness must deliver 15–20 % better R-value; infrared-absorbing graphite lowers conductivity at identical low density. | — | 0.14 | 2 | — |
Shape-molded (tool-molded) EPS parts | Use when the part geometry is molded directly in a tool (helmet liners, appliance packs, EPS forms) instead of cut from block; skin gives slightly better surface strength. | — | 0.15 | 2 | — |
What is C578 Type I GEO15?
C578 Type I GEO15 is C578 Type I in the GEO15 grade — same nominal density supplied as large lightweight-fill blocks specified by strain-level compressive resistance rather than by C578 board properties. C578 Type I GEO15 has a tensile strength of 0.1 MPa (0.0145 ksi), weaker than 99% of polymer grades. The elastic modulus is 0 GPa (2.18×10⁻⁴ Msi). C578 Type I GEO15 has a density of 0.02 g/cm³ (5.42×10⁻⁴ lb/in³), lighter than 100% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Advantages
- Lightweight — 0.02 g/cm³ (5.42×10⁻⁴ lb/in³), better than 100% of polymer grades
- Easy to machine — 85/100, better than 88% of polymer grades
- Low embodied carbon — 3.3 kg CO₂/kg, better than 78% of polymer grades
Limitations
- Degrades in UV without stabilisers — 12/100, worse than 99% of polymer grades
- Low stiffness — 0 GPa (2.18×10⁻⁴ Msi), worse than 96% of polymer grades
- Poor heat conductor — 0.04 W/m·K (0.0237 BTU/hr·ft·°F), worse than 86% of polymer grades
- Absorbs moisture — dry before molding — 1%, worse than 84% of polymer grades
- Needs corrosion protection — 70/100, worse than 78% of polymer grades
C578 Type I GEO15 properties
Typical room-temperature values for C578 Type I GEO15; 19 are specific to this condition. Other listed values are C578 Type I reference data and may not represent this condition. Bars are the position among polymer grades.
Physical4
C578 Type I GEO15 has a density of 0.02 g/cm³ (5.42×10⁻⁴ lb/in³), lighter than 100% of polymer grades. Its glass-transition temperature is 100°C (212 °F).
Mechanical7
C578 Type I GEO15 has a tensile strength of 0.1 MPa (0.0145 ksi), weaker than 99% of polymer grades. The elastic modulus is 0 GPa (2.18×10⁻⁴ Msi).
Thermal9
C578 Type I GEO15 is rated for continuous service to 75°C (167 °F). It conducts heat at 0.04 W/m·K (0.0237 BTU/hr·ft·°F), worse than 86% of polymer grades. Thermal expansion is 65 µm/m·K (36.1 µin/in·°F).
Electrical4
Chemical & Environmental3
Corrosion resistance is very good (70/100), worse than 78% of polymer grades. UV resistance is not recommended.
Sustainability4
Producing a kilogram of C578 Type I GEO15 takes about 105 MJ of energy and emits 3.3 kg of CO₂ — more than 54% of polymer grades. Typical recycled content is 5%.
Manufacturability4
C578 Type I GEO15's machinability is excellent (85/100, better than 88% of polymer grades); weldability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C578 Type I GEO15
Is C578 Type I easy to machine?
Hot-wire cutting gives the cleanest edge; band saw, router or CNC hot-knife also work, but keep tools sharp and avoid solvent coolants — dry cutting leaves static-clinging bead dust.
Can C578 Type I be welded?
No conventional welding: blocks and parts are joined by steam fusion in the mold, by hot-plate/hot-wire tacking, or with water-based/EPS-safe adhesives.
Can C578 Type I be formed, bent or molded?
Pre-expand bead with steam to the target 14–16 kg/m³, age 6–24 h, then steam-mold blocks or shapes at ~0.5–1.0 bar; blocks must be cured several days before cutting to stabilize dimensions.
What surface finishes work on C578 Type I?
Coat only with water-based or EPS-compatible paints, cement/acrylic renders or laminated facers; solvent-based paints, bituminous primers and PVC plasticizers dissolve or shrink the foam, and all exposed surfaces need UV protection.
C578 Type I chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| pentane (blowing agent, residual)n-/iso-pentane; largely diffused out after ageing | 0.2 – 6 | 3 |
| polymeric brominated flame retardantpolymeric FR (HBCD-free) in building grade; absent in non-FR packaging bead | 0.5 – 1.5 | 0.9 |
| nucleating / coating agents (waxes, steabead surface coating for fusion and antistatic control | 0.1 – 0.8 | 0.3 |
| air (closed cells)≈98 % by volume of the finished foam, not by weight | ≈ 98 | 98 |
| polystyrene (styrene homopolymer)expandable bead base resin | ≥ 90 (balance) | — |
C578 Type I GEO15 — frequently asked
What is C578 Type I GEO15 used for?
C578 Type I GEO15 is typically used for under-slab insulation, void fill, packaging blocks and low-load cavity fill. In short: lowest-density C578 EPS; lowest-cost insulating foam; non-load-bearing fill only.
What is the tensile strength of C578 Type I GEO15?
C578 Type I GEO15 has a typical tensile strength of 0.1 MPa (0.0145 ksi) — weaker than 99% of polymer grades. Strength varies by condition: see the 5 listed tempers.
Is C578 Type I GEO15 easy to machine?
Yes — machinability is rated excellent (85/100, better than 88% of polymer grades). Hot-wire cutting gives the cleanest edge; band saw, router or CNC hot-knife also work, but keep tools sharp and avoid solvent coolants — dry cutting leaves static-clinging bead dust.
Can C578 Type I GEO15 be welded?
Not readily — weldability is rated poor (25/100). No conventional welding: blocks and parts are joined by steam fusion in the mold, by hot-plate/hot-wire tacking, or with water-based/EPS-safe adhesives.
What surface finishes work on C578 Type I GEO15?
Coat only with water-based or EPS-compatible paints, cement/acrylic renders or laminated facers; solvent-based paints, bituminous primers and PVC plasticizers dissolve or shrink the foam, and all exposed surfaces need UV protection.
Can C578 Type I GEO15 be formed, bent or molded?
Pre-expand bead with steam to the target 14–16 kg/m³, age 6–24 h, then steam-mold blocks or shapes at ~0.5–1.0 bar; blocks must be cured several days before cutting to stabilize dimensions.
What is the maximum service temperature of C578 Type I GEO15?
C578 Type I GEO15 is rated for continuous use to about 75°C (167 °F), and briefly to 85°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM C578 — Standard Specification for Rigid, Cellular Polystyrene Thermal Insulation — ASTM International (2022)
- ASTM D6817 — Standard Specification for Rigid Cellular Polystyrene Geofoam — ASTM International (2021)
- Handbook of Polymeric Foams and Foam Technology — Hanser (2004)
- EPS insulation board technical data (density, R-value, compressive resistance) — EPS Industry Alliance / BASF Neopor (2023)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.