Crumb rubber specification sheet by mesh and grinding method
ASTM D5603 pass-or-fail specification limits for crumb rubber across four mesh bands — covering specific gravity, bulk density, moisture, free metal, and fibre content — the reference standard for batch certificate of analysis and offtake agreements.
| Mesh band | Particle size | Specific gravity (g/cc) | Bulk density (kg/m³) | Moisture limit | Free metal limit | Fibre limit |
|---|---|---|---|---|---|---|
| Coarse 4-30 mesh | 0.6-4.7 mm | 1.10-1.15 | 380-480 | below 0.75% | below 0.01% | below 0.5% |
| Mid-coarse 10-30 mesh | 0.6-2.0 mm | 1.10-1.15 | 420-520 | below 0.75% | below 0.01% | below 0.3% |
| Fine 30-80 mesh | 0.18-0.6 mm | 1.15-1.20 | 480-580 | below 0.5% | below 0.005% | below 0.1% |
| Ultra-fine 80-100+ mesh | Below 0.18 mm | 1.15-1.20 | 520-620 | below 0.5% | below 0.005% | below 0.05% |
Beyond definitions
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How to read this table
- All limits are maximums unless otherwise stated — the material must be below the listed percentage to pass
- Specific gravity and bulk density are ranges (not maxima) — material outside the range may indicate incorrect grinding or contamination
- Test methods reference Indian Standard (IS) equivalents where applicable; ASTM D5603 is the governing standard for export-linked or technically demanding contracts
- Free metal limit of 0.005% for fine and ultra-fine bands requires effective magnetic separation — verify separator efficiency with a calibrated test before committing to offtake
About this table
Every crumb rubber sale to a serious buyer — asphalt plants, moulded product manufacturers, CRMB producers — requires a batch certificate of analysis (COA) that demonstrates the material meets agreed specifications. The most widely referenced quality standard in India's crumb rubber trade is ASTM D5603, the American Society for Testing and Materials classification for rubber from scrap tyres. This table presents the key pass-or-fail limits per mesh band so that a plant operator can set up in-house quality control testing against the correct targets before issuing a COA.
The specifications tighten as the mesh band gets finer. Specific gravity is consistent at 1.10 to 1.15 for coarse and mid-coarse bands but rises slightly to 1.15 to 1.20 for fine and ultra-fine material, reflecting the denser, more uniform particle structure. Bulk density increases progressively from 380 to 480 kg per cubic metre for coarse material to 520 to 620 kg per cubic metre for ultra-fine, which matters for storage tank sizing and transport load calculation. Moisture limits tighten from below 0.75 percent for coarse bands to below 0.5 percent for fine and ultra-fine — important because moisture above these limits indicates inadequate drying and can cause clumping during storage or processing at the buyer's plant.
Free metal limits are the most unforgiving specification. Even a trace of steel wire contamination above 0.01 percent for coarse material or 0.005 percent for fine and ultra-fine will cause immediate rejection by asphalt plants and moulded product buyers, and can damage processing equipment at the buyer's facility. Magnetic separation efficiency is therefore a quality control checkpoint, not just a throughput consideration. Fibre limits follow the same tightening pattern — below 0.5 percent for coarse material dropping to below 0.05 percent for ultra-fine.
Use this table alongside the Mesh-Band Output from Ambient Grinding Line table to understand what yield share you are producing at each specification band, and the Top 3 Crumb Rubber Applications table to confirm which buyers require which specification tiers. A well-run plant should test each batch using a certified laboratory before dispatch and retain COA records for audit by buyers and regulators.
Key insights
- Free metal limits tighten from 0.01 percent for coarse bands to 0.005 percent for fine and ultra-fine — magnetic separator efficiency is the single most critical quality control step
- Bulk density ranges increase from 380 to 480 kg per cubic metre for coarse to 520 to 620 for ultra-fine, directly affecting storage tank sizing and transport economics
- Moisture above 0.5 percent in fine or ultra-fine material causes clumping in storage and will be rejected by moulded product and sealant buyers
- ASTM D5603 is the reference standard for technically demanding Indian offtake contracts — a COA that cites this standard signals to buyers that the plant runs controlled quality processes
- Fibre limits are ten times tighter for ultra-fine (0.05%) than for coarse (0.5%) — cross-contamination from the tyre's steel-belt fibre layer at fine grinding stages will breach this limit
Methodology & sources
Specifications are from ASTM D5603 classification for rubber from scrap tyres. Bulk density values reflect typical ambient-ground crumb rubber; cryogenically produced material may show slightly different density profiles. Moisture and contamination limits reflect standard Indian offtake contract requirements as of 2024–25; individual buyers may specify tighter limits for high-specification applications.
Related data tables
Crumb rubber mesh-band output from an ambient grinding line
Yield share, particle size range, primary application, and indicative price for the four mesh bands — coarse, mid-coarse, fine, and ultra-fine — that an ambient grinding line produces from waste tyres.
Quality Control Testing Methods and Standards
Six quality control testing standards used in tyre recycling — covering ASTM standards for crumb rubber and reclaimed rubber, IS 15462 and IRC SP:53 for Indian CRMB certification, and ASTM D6114 for international CRMB qualification.
Top 3 crumb rubber applications in India side-by-side
Side-by-side comparison of the three largest crumb rubber application families in India — civil and infrastructure, moulded products, and sports surfaces — showing mesh band, volume share, typical lot size, contract type, and contamination specification.