CRMB 55 Bitumen Specification
Last updated: 2026-10-01
CRMB 55 Bitumen Specification
CRMB 55 is a crumb rubber modified bitumen classified under IS 15462:2019 with a minimum softening point of 55°C, penetration value of 50–70 dmm at 25°C, and elastic recovery of at least 50%. It is produced by blending 8–12% waste crumb rubber (typically 30–80 mesh) into VG-30 or VG-40 base bitumen at 175–185°C for 45–60 minutes. In 2025, CRMB 55 trades at approximately USD 480–560 per metric ton FOB India, roughly 12–18% above unmodified VG-30 pricing.
What Is CRMB 55 Bitumen?
CRMB 55 stands for Crumb Rubber Modified Bitumen, grade 55 — the "55" refers to the minimum softening point of 55°C specified in IS 15462 (Indian Standards for Polymer and Rubber Modified Bitumen). It is a wet-process modified binder in which reclaimed tire rubber is chemically and physically integrated into penetration-grade or viscosity-grade bitumen.
Composition breakdown:
- Base bitumen: VG-30 or VG-40 (85–92% by weight)
- Crumb rubber: 8–12% by weight, 30–80 mesh (0.18–0.6 mm particle size)
- Additives/stabilizers: 0.5–2% (process oils, cross-linking agents)
- Blending temperature: 175–185°C
- Digestion/maturation time: 45–60 minutes under continuous agitation
CRMB 55 is primarily used in high-traffic road construction — national highways, expressways, and urban arterial roads — because the rubber network raises rutting resistance and fatigue life by 30–50% compared with conventional VG-30.
CRMB 55 Physical and Performance Specifications
The table below summarizes the mandatory requirements per IS 15462:2019 (Table 1, Grade CRMB 55):
| Property | Test Method | CRMB 55 Requirement | Typical VG-30 (Reference) |
|---|---|---|---|
| Penetration at 25°C, 100g, 5s | IS 1203 | 50–70 dmm | 45–70 dmm |
| Softening Point (R&B) | IS 1205 | Min. 55°C | 47–52°C |
| Elastic Recovery at 15°C | IS 15462 Annex | Min. 50% | <10% |
| Flash Point (Cleveland Open Cup) | IS 1209 | Min. 220°C | Min. 220°C |
| Viscosity at 150°C | IS 1206 | 1.0–2.5 Pa·s | 0.4–0.8 Pa·s |
| Specific Gravity at 27°C | IS 1202 | Min. 1.00 | 1.01–1.03 |
| Solubility in Trichloroethylene | IS 1216 | Min. 97% | Min. 99% |
| Thin Film Oven Test (TFOT) — % loss | IS 9382 | Max. 1.0% | Max. 1.0% |
| TFOT — Penetration retained | IS 1203 | Min. 60% | Min. 55% |
| TFOT — Softening point increase | IS 1205 | Max. 6°C | Max. 6°C |
| Storage Stability (48h at 163°C, ΔSP) | IS 15462 Annex | Max. 4°C | N/A |
Key takeaway for specifiers: The two binding performance parameters are the softening point (≥55°C) and elastic recovery (≥50%). Together they define the rutting and elastic performance of the binder — elasticity is what distinguishes CRMB 55 from straight-run bitumen.
CRMB 55 vs VG-30 vs CRMB 60 vs PMB 40: Comparison
Different modified binders serve different traffic and climate conditions. This table compares the four most commonly cross-specified grades in South Asian and Middle East tenders:
| Parameter | VG-30 | CRMB 55 | CRMB 60 | PMB 40 (SBS) |
|---|---|---|---|---|
| Softening Point | 47–52°C | ≥55°C | ≥60°C | ≥60°C |
| Elastic Recovery @15°C | <10% | ≥50% | ≥60% | ≥80% |
| Penetration @25°C | 45–70 dmm | 50–70 dmm | 40–60 dmm | 40–60 dmm |
| Crumb Rubber Content | 0% | 8–12% | 10–15% | 0% (SBS 3–5%) |
| Mixing Temp (Plant) | 150–160°C | 165–175°C | 170–180°C | 165–175°C |
| Indicative Price (USD/MT FOB) | 420–470 | 480–560 | 510–590 | 620–750 |
| Best Application | Moderate traffic | High traffic, hot climate | Heavy traffic, very hot climate | Premium highways, extreme loads |
| Recycled Content | None | High (waste tires) | High | None |
| Typical Service Life Gain | Baseline | +30–50% | +40–60% | +50–80% |
When to specify CRMB 55:
- Traffic loading of 10–30 MSA (million standard axles)
- Maximum pavement temperature of 45–50°C
- Budget sensitivity: CRMB 55 costs 22–30% less than equivalent SBS polymer-modified bitumen
- Sustainability requirements: each ton of CRMB 55 consumes approximately 80–120 waste tires
Production, Handling, and Application Data
1. Base bitumen heating to 175–180°C in a stirred tank
2. Crumb rubber dosing at 8–12% by weight (30–80 mesh)
3. High-shear mixing for 30–45 minutes (2,000–4,000 rpm)
4. Digestion at 175–185°C for 45–60 minutes
5. Quality testing (penetration, softening point, elastic recovery)
6. Storage at 150–160°C with slow agitation (max 48 hours recommended)
| Parameter | Value |
|---|---|
| Mixing temperature at HMA plant | 165–175°C |
| Compaction temperature | 140–155°C |
| Aggregates heating temperature | 175–190°C |
| Optimal binder content (BC mix) | 5.0–6.5% by weight |
| Compacted density target | 2.35–2.45 g/cm³ |
| Recommended layer thickness | 40–50 mm (BC), 25–40 mm (DBM) |
- Do not store above 180°C — rubber degradation accelerates above this threshold
- Limit storage time to 48 hours maximum; beyond this, softening point drift exceeds 4°C (fails IS storage stability)
- Avoid pumping through high-pressure lines without pre-heating to 150°C minimum
- CRMB 55 is not compatible with unmodified bitumen in the same tank without full drainage
CRMB 55 Pricing and Market Data (2025)
| Market | Price Range (USD/MT) | Basis |
|---|---|---|
| India (domestic) | 430–510 | Ex-works, bulk |
| India (FOB Mundra/JNPT) | 480–560 | FOB, in drums or bulk |
| Bangladesh (CIF Chittagong) | 520–610 | CIF, drummed |
| UAE / GCC (CIF Jebel Ali) | 540–630 | CIF, bulk flexitank |
| East Africa (CIF Mombasa) | 560–660 | CIF, drummed |
| Southeast Asia (CIF) | 530–620 | CIF, drummed |
Price drivers to monitor:
- Crumb rubber feedstock: USD 180–260/MT (largely tracks tire recycling supply)
- VG-30 base bitumen: USD 400–460/MT FOB (tracks crude oil benchmarks)
- Freight: USD 40–90/MT depending on route and packaging
- Packaging delta: bulk flexitank is USD 25–40/MT cheaper than new steel drums
Volume context: Typical minimum order quantity (MOQ) for export is 20 MT (one 20-ft container in flexitank) or 18 MT in drummed configuration. Large highway projects consume 200–800 MT per 10 km lane of 40 mm bituminous concrete.
FAQ: CRMB 55 Bitumen
Q1: What does the "55" in CRMB 55 stand for?
The "55" denotes the minimum softening point of 55°C as measured by the Ring & Ball method per IS 1205. It is not a penetration grade or a viscosity grade — it is a thermal performance grade indicating rutting resistance in hot climates.
Q2: What is the difference between CRMB 55 and CRMB 60?
CRMB 60 requires a minimum softening point of 60°C and higher elastic recovery (≥60%), making it suitable for heavier traffic and hotter climates. CRMB 55 handles 10–30 MSA loading, while CRMB 60 is specified for 30+ MSA corridors. CRMB 60 costs roughly USD 30–40/MT more.
Q3: Can CRMB 55 be used in cold climates?
CRMB 55 is formulated for hot climates (pavement temperatures up to 50°C). In cold regions with low-temperature cracking risk, CRMB 55's high stiffness may cause brittleness below 0°C. For mixed climates, consider CRMB 55 with viscosity-graded base or switch to a lower softening-point grade.
Q4: How much crumb rubber is in CRMB 55?
Standard IS 15462 formulations incorporate 8–12% crumb rubber by weight of the total binder, typically 30–80 mesh particle size. This equates to approximately 80–120 recycled tires per metric ton of finished binder.
Q5: What is the shelf life and storage temperature of CRMB 55?
CRMB 55 should be stored at 150–160°C with slow agitation and used within 48 hours of production to maintain specification compliance. Storage above 180°C causes rubber degradation and softening point drift; storage beyond 48 hours typically fails the IS storage stability test (max 4°C ΔSP).
Calculate Your CRMB 55 Project Cost in Seconds
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- Total binder tonnage required for your road length, width, and layer thickness
- FOB / CIF landed cost including freight and packaging
- Cost comparison against VG-30, CRMB 60, and PMB 40 alternatives
- Waste-tire diversion and sustainability metrics for green procurement reporting
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