CRMB 55 Bitumen Specification
Last updated: 2026-09-29
CRMB 55 is a crumb rubber–modified bitumen grade produced by blending 55% crumb rubber content (by weight of the rubber modifier masterbatch) into penetration-grade bitumen, typically VG-30 or VG-40. The resulting binder delivers a penetration value of 50–70 dmm at 25°C, a softening point of 50–65°C, and elastic recovery above 60%, making it suitable for hot-mix asphalt in high-traffic and high-temperature regions. Standard pricing for CRMB 55 in bulk export quantities (20–28 MT ISO tank or drummed loads) ranges from $520–$680 per metric ton FOB India depending on crude feedstock and order volume.
What Is CRMB 55? Definition and Composition
CRMB 55 (Crumb Rubber Modified Bitumen, grade 55) is a polymer-modified bitumen where the modifier is waste tyre crumb rubber rather than virgin SBS polymer. The "55" designation refers to the formulation standard — in Indian Standard IS 15462, CRMB grades are labeled by their crumb rubber content and performance class (CRMB 50, CRMB 55, CRMB 60). CRMB 55 uses a higher rubber dosage than CRMB 50, which raises viscosity, elasticity, and rutting resistance.
Key composition components:
- Base bitumen: VG-30 or VG-40 penetration grade (85–90% of final blend by weight)
- Crumb rubber modifier: 40–60 mesh cryogenic or ambient-ground tyre rubber (10–15% by weight of base bitumen)
- Compatibilizer/aromatic oil: 1.5–3% to stabilize the rubber-bitumen interface
- Stabilizing agent: 0.1–0.3% sulfur or cross-linking additive
The crumb rubber swells and partially devulcanizes during high-shear mixing at 180–195°C for 45–90 minutes, creating a three-dimensional network that absorbs lighter bitumen fractions and stiffens the binder.
| Property | CRMB 55 (IS 15462) | VG-30 (IS 73) | SBS PMB 40 |
|---|---|---|---|
| Penetration @ 25°C (dmm) | 50–70 | 45–70 | 40–60 |
| Softening point (°C) | 50–65 | 47–55 | 60–75 |
| Elastic recovery (%) | ≥ 60 | N/A | ≥ 75 |
| Viscosity @ 150°C (Pa·s) | 1.5–3.0 | 0.4–0.8 | 1.2–2.5 |
| Flash point (°C) | ≥ 220 | ≥ 220 | ≥ 220 |
| Solubility in TCE (%) | ≥ 97 | ≥ 99 | ≥ 98 |
CRMB 55 Performance Data and Test Specifications
CRMB 55 is engineered for pavements carrying over 30 million standard axles (MSA) and operating in climates with pavement temperatures reaching 50–60°C. Its elastic recovery is the primary differentiator — it rebounds from deformation rather than flowing permanently.
Comparative test data (typical values across 5 production lots):
| Test Parameter | Test Method | Min | Max | Typical |
|---|---|---|---|---|
| Penetration @ 25°C | IS 1203 | 50 | 70 | 58 |
| Softening point | IS 1205 | 50 | 65 | 57 |
| Ductility @ 27°C (cm) | IS 1208 | 50 | — | 68 |
| Elastic recovery | IS 15462 App. B | 60 | — | 72 |
| Thin film oven test (TFOT) loss | IS 9382 | — | 1.0% | 0.6% |
| Penetration ratio after TFOT | — | 60 | — | 71 |
| Specific gravity | IS 1202 | 1.01 | 1.06 | 1.03 |
Performance benchmarks vs. base VG-30:
- Rutting resistance at 60°C: 35–50% improvement in dynamic creep
- Fatigue life: 2–3× longer under repeated loading
- Moisture susceptibility (TSR): 85–92% vs. 75–80% for VG-30
- Service life extension: 4–7 additional years on high-traffic corridors
These numbers explain why CRMB 55 is specified on expressway projects in India, Southeast Asia, and parts of Africa and the Middle East.
CRMB 55 vs CRMB 50 vs CRMB 60: Grade Comparison
Grade selection depends on traffic load and climate. Below is a direct comparison.
| Parameter | CRMB 50 | CRMB 55 | CRMB 60 |
|---|---|---|---|
| Crumb rubber content | ~50 mesh equivalent | 55 formulation | ~60 formulation |
| Softening point (°C) | 47–60 | 50–65 | 55–70 |
| Elastic recovery (%) | ≥ 50 | ≥ 60 | ≥ 70 |
| Typical use | Moderate traffic | Heavy traffic, highways | Extreme traffic, airports |
| Viscosity @ 150°C (Pa·s) | 1.2–2.2 | 1.5–3.0 | 2.0–4.0 |
| Mixing temp (°C) | 160–170 | 165–175 | 170–180 |
| Approx. price FOB ($/MT) | 480–600 | 520–680 | 580–740 |
| Recommended MSA | < 20 | 20–50 | > 50 |
Selection logic:
- Under 20 MSA, mild climate → CRMB 50 is cost-efficient
- 20–50 MSA, hot climate → CRMB 55 is the standard specification
- Over 50 MSA, airports, container yards → CRMB 60
CRMB 55 occupies the sweet spot: it meets most national highway specifications while costing 8–12% less than CRMB 60 for nearly equivalent performance in most field conditions.
CRMB 55 Application, Mixing, and Storage
Applications:
- National highway wearing courses (BC/SDBC)
- Expressway overlays
- Urban arterial roads with heavy bus traffic
- Bridge deck waterproofing
- Airport taxiways (where CRMB 60 is not mandated)
Mixing parameters:
| Stage | Temperature | Duration |
|---|---|---|
| Crumb rubber–bitumen blending | 180–195°C | 45–90 min |
| Hot mix plant discharge | 165–175°C | — |
| Laydown | ≥ 150°C | — |
| Initial rolling | 140–150°C | — |
| Storage (with agitation) | 150–165°C | max 8 hours |
| Storage (static, no agitation) | avoid > 4 hours | risk of settlement |
Storage and handling rules:
- CRMB 55 separates if stored static — agitation every 2–4 hours is mandatory
- Do not exceed 175°C during storage to prevent rubber degradation
- Tank heating coils should maintain 150–165°C steady state
- Consume within 72 hours of production for peak performance
- Transport in insulated ISO tanks with 20–28 MT capacity
Logistics reference:
| Mode | Typical Volume | Lead Time (India → SE Asia) |
|---|---|---|
| ISO tank | 20–24 MT | 12–18 days |
| Drummed (new steel drums) | 180–200 kg/drum | 15–22 days |
| Flexitank | 22–24 MT | 14–20 days |
| Bulk vessel parcel | 500–5,000 MT | 18–30 days |
Pricing, Market Trends, and Procurement
CRMB 55 pricing tracks three inputs: base bitumen (VG-30/40) cost, crumb rubber cost, and freight. Base bitumen is roughly 80–85% of the final price, so crude oil movements dominate.
Indicative price bands (FOB India, 2024–2025):
| Quantity | Packaging | Price Range ($/MT) |
|---|---|---|
| 20–50 MT | ISO tank/drums | 560–680 |
| 50–200 MT | ISO tank | 540–640 |
| 200–1,000 MT | Flexitank/vessel | 520–600 |
| 1,000+ MT | Bulk parcel | 500–580 |
Market drivers to monitor:
- Crude oil (Brent): every $10/bbl move shifts base bitumen by roughly $35–50/MT
- Crumb rubber supply: tyre recycling rates in India, China, and EU affect modifier cost
- Freight rates: container and tanker rates can swing delivered cost by 8–15%
- Specification drift: more agencies adopting CRMB 55 over CRMB 50 has raised demand 10–15% year over year
Procurement checklist:
- Request batch-wise test certificates (penetration, softening point, elastic recovery)
- Verify IS 15462 or equivalent (ASTM D6114 for polymer-modified blends) compliance
- Confirm agitation-equipped storage at destination port
- Lock pricing on base + modifier + freight separately to hedge crude volatility
- Inspect drum/tank seals and check for settlement before unloading
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FAQ: CRMB 55 Bitumen
What does "55" mean in CRMB 55?
The "55" refers to the formulation grade under IS 15462, indicating a crumb rubber content and performance class higher than CRMB 50 and below CRMB 60. It is defined by properties like a 50–70 dmm penetration and ≥ 60% elastic recovery, not a literal 55% rubber content.
What is the price of CRMB 55 per metric ton?
CRMB 55 typically sells for $520–$680 per metric ton FOB India depending on order volume, packaging, and crude feedstock timing. Bulk parcels above 1,000 MT can price as low as $500/MT, while small drummed orders run $650–$680/MT.
How does CRMB 55 differ from CRMB 50?
CRMB 55 has a higher softening point (50–65°C vs 47–60°C) and elastic recovery (≥ 60% vs ≥ 50%), giving better rutting resistance. It is specified for 20–50 MSA traffic, whereas CRMB 50 suits under 20 MSA.
Can CRMB 55 be stored without agitation?
No — CRMB 55 will settle and separate if left static for more than 4 hours. Storage tanks must be agitated every 2–4 hours and held at 150–165°C, with consumption ideally within 72 hours of production.
What is the minimum order quantity for CRMB 55 export?
Most exporters ship CRMB 55 starting at a 20 MT ISO tank or a 20-foot container of drums (about 18–20 MT). Flexitank and bulk vessel options begin at 22 MT and 500 MT respectively.
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