Bitumen 40/50 Bhutan
Last updated: 2026-10-19
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Bitumen 40/50 Bhutan is a penetration-graded bitumen with a penetration range of 40–50 dmm (0.1 mm at 25°C), supplied to the Bhutanese market mainly for National Highways Authority (NHA) road construction and DANTAK (Border Roads Organisation) infrastructure projects. Delivered prices from Indian refineries into Phuentsholing typically range USD 480–560 per metric ton (INR 40,000–46,500/MT), depending on origin, packaging, and freight via the Jaigaon–Phuentsholing corridor; bulk tanker lead times run 7–14 days from Guwahati or Siliguri depots. Because Bhutan has no domestic refinery capacity, 100% of its bitumen is imported—almost entirely from India—and demand concentrates in the March–June and September–November construction windows.
What Is Bitumen 40/50 and Why Bhutan Specifies It
Bitumen 40/50 is a medium-hard penetration grade defined under IS 73:2013 (India) and aligned with ASTM D946. In Bhutan, the Department of Roads (DoR), Ministry of Infrastructure and Transport, follows IS 73 / AASHTO M20 specifications for highway works. Grade 40/50 sits between softer 60/70 and harder 30/40 grades, making it well-suited to Bhutan's climate band, where road surface temperatures in the southern foothills (Phuentsholing, Gelephu, Samdrup Jongkhar) regularly exceed 50°C in summer.
Where it is used in Bhutan:
- NHA road construction — National Highways (e.g., Phuentsholing–Thimphu, Gelephu–Trongsa) use 40/50 for dense bituminous macadam (DBM) and bituminous concrete (BC) wearing courses.
- DANTAK projects — Border Roads Organisation works in high-altitude and foothill corridors.
- Airport and municipal works — Paro International Airport runway maintenance and dzongkhag (district) urban roads.
- Hydro and industrial access roads — plant roads for hydropower projects (Punatsangchhu, Mangdechhu corridors).
Climate fit: Bhutan's south is hot and humid (Zone A/B), while central and northern regions (Thimphu, Bumthang) are cooler. Grade 40/50 is the default for lower and mid-altitude zones; higher passes often specify 60/70 or PMB for low-temperature crack resistance.
Key Physical Specifications: Bitumen 40/50 (IS 73:2013 / ASTM D946)
| Property | Test Method | Bitumen 40/50 Requirement |
|---|---|---|
| Penetration @ 25°C, 100 g, 5 s | IS 1203 / ASTM D5 | 40–50 dmm |
| Softening point (R&B) | IS 1205 / ASTM D36 | 50–62°C (typical 52–58°C) |
| Ductility @ 25°C | IS 1208 / ASTM D113 | Min. 75 cm (typical 100+ cm) |
| Flash point (Cleveland open cup) | IS 1209 / ASTM D92 | Min. 220°C |
| Solubility in trichloroethylene | IS 1216 / ASTM D2042 | Min. 99.0% |
| Viscosity @ 135°C | ASTM D4402 | 0.2–0.4 Pa·s (typical) |
| Specific gravity @ 27°C | IS 1202 / ASTM D70 | 1.01–1.06 |
| Loss on heating (163°C, 5 h) | IS 1212 / ASTM D1754 | Max. 1.0% |
| Penetration after heating (retained % of original) | IS 1203 | Min. 55–60% |
| Grade after thin film oven test (TFOT) | IS 9382 / ASTM D1754 | Retained penetration 55–62% |
Notes: Specification values vary slightly by source mix (Indian refinery vs. Middle East import). Always confirm against the NHA Bhutan-approved mix design.
For contractors, the two most critical values are penetration (40–50 dmm) and softening point (≥50°C) — the first controls workability and compaction temperature, the second controls rutting resistance in Bhutan's hot southern plains. Viscosity @ 135°C (0.2–0.4 Pa·s) governs pumpability in bulk handling.
Bitumen 40/50 vs Competing Grades: Bhutan Buyer Comparison
| Parameter | Bitumen 40/50 | Bitumen 60/70 | Bitumen 30/40 | PMB 40 |
|---|---|---|---|---|
| Penetration @ 25°C (dmm) | 40–50 | 60–70 | 30–40 | 40–50 |
| Softening point (°C) | 50–62 | 45–58 | 55–65 | 60–75 |
| Climate fit (Bhutan) | Hot–moderate zones | Cooler northern zones | Heavy-traffic, hot zones | High-stress bridges, junctions |
| Typical delivered price to Phuentsholing (USD/MT, bulk) | 480–560 | 470–550 | 520–600 | 620–750 |
| Rutting resistance | Good | Moderate | High | Very high |
| Low-temperature crack risk | Moderate | Low | Higher | Low |
| Common use in Bhutan | DBM/BC wearing course, state roads | Hill roads, cooler districts | Expressway-grade, heavy truck corridors | Bridge decks, urban junctions |
| Availability (Indian refineries) | High | Very high | Medium | Medium (import) |
Key takeaway: 40/50 costs roughly 2–3% more than 60/70 per ton but delivers better rutting resistance on Bhutan's southern plains, where summer pavement temperatures exceed 50°C. For roads above 2,000 m (Thimphu, Trashigang, Bumthang), 60/70 is often preferred; for heavy industrial corridors, 30/40 or PMB 40 is the engineered choice.
Bhutan Import Logistics: Cost, Time, and Lead Times
Bhutan's only land border with India for bulk goods is the Jaigaon–Phuentsholing crossing, with secondary routes via Gelephu (Assam/SE border) and Samdrup Jongkhar. Bitumen typically originates from Indian Oil Corp (IOC), BPCL, HPCL, or Numaligarh Refinery (NRL) depots in Guwahati, Siliguri, or New Jalpaiguri.
| Item | Detail |
|---|---|
| Typical delivery terms | Ex-depot India, or CFR Phuentsholing |
| Bulk prices (India-origin, May–July 2024 range) | INR 40,000–46,500/MT (≈ USD 480–560/MT) |
| Packaging | Bulk tanker (most common), steel drums 181–200 kg, bitumen bags |
| Lead time from Guwahati/Siligurai | 7–14 days (bulk tanker) |
| Lead time from Middle East (Dubai, Iran) via Kolkata | 25–40 days |
| Freight, Siliguri → Phuentsholing | ≈ INR 1,500–2,500/MT |
| Customs / trade fee | ~0.5–1% of import value, plus GST on imports |
| Minimum economical bulk order | 20–25 MT (one tanker) |
| Seasonal demand peak | March–June and September–November |
| Monsoon slowdown | July–August (transport risk, high rainfall) |
Key logistics facts:
- No rail link into Bhutan — all bulk bitumen moves by road tanker.
- Phuentsholing handles the majority of bitumen imports; Gelephu is a growing second gateway.
- Bulk tankers must be temperature-controlled (140–160°C) for offloading into insulated storage at the hot mix plant or contractor depot.
- Seasonal price spikes of 5–10% occur just before the March–June construction peak.
Bhutan Selection & Purchasing Checklist
For contractors and procurement teams, evaluate suppliers against these criteria:
- Specification conformity — IS 73:2013 or AASHTO M20 test certificates for every batch.
- Penetration and softening point pairing — 40–50 dmm penetration with softening point of 50–62°C; avoid outliers below 50°C in the south.
- Retained penetration after TFOT — ≥55% is a reliable quality marker.
- Delivery reliability — confirmed tanker dispatch schedules from the Indian depot and clear customs clearance at Phuentsholing.
- Price structure — compare delivered-to-site cost, not ex-refinery price, including freight, customs, and storage.
- Payment terms — most Bhutan importers transact in Indian rupees or US dollars; compare landed cost in both.
- Packaging fit — bulk for large sites, drums (181–200 kg) or bitumen bags for remote or small-works projects where tankers can't turn around.
- Supplier track record — references for NHA/DANTAK projects and consistent supply through the monsoon gap.
- Storage readiness — insulated tank capacity of at least 1.5× monthly consumption (typically 20–60 MT for mid-size contractors).
Quick pricing benchmark: an order of 100 MT of bulk 40/50 delivered to Phuentsholing at USD 520/MT totals ≈ USD 52,000 plus ~USD 10,000–15,000 freight and logistics — a USD 60,000–65,000 landed total, depending on origin and season.
FAQ: Bitumen 40/50 Bhutan
Q1: What is the price of bitumen 40/50 in Bhutan?
Bulk bitumen 40/50 delivered to Phuentsholing typically costs USD 480–560 per MT (INR 40,000–46,500/MT) ex-depot India, including freight and customs but not local handling. Prices fluctuate with crude oil and peak 5–10% higher in the March–June construction season.
Q2: Which grade of bitumen is used in Bhutan road construction?
Bhutan's Department of Roads and NHA specify 40/50 as the default grade for hot-mix wearing courses and DBM in southern and mid-altitude districts, while 60/70 is common for cooler northern regions and PMB 40 for high-stress bridge and urban projects.
Q3: Where does Bhutan import bitumen from?
Bhutan imports 100% of its bitumen, almost entirely from Indian refineries (IOCL, BPCL, HPCL, Numaligarh) via the Jaigaon–Phuentsholing border, with some specialty grades like PMB sourced from Middle East or Indian processing units.
Q4: What is the lead time for bitumen delivery to Bhutan?
Bulk tanker delivery from Indian depots in Guwahati or Siliguri to Phuentsholing takes 7–14 days, depending on border clearance, while larger imported consignments from the Middle East via Kolkata add 25–40 days by sea plus road transit.
Q5: What specifications must bitumen 40/50 meet for Bhutanese projects?
Bitumen 40/50 supplied to Bhutan must meet IS 73:2013 (or AASHTO M20), with 40–50 dmm penetration at 25°C, softening point of 50–62°C, ≥75 cm ductility, and ≥220°C flash point, and every batch requires a third-party test certificate accepted by the NHA.
Ready to price your next bitumen shipment? Use the 6Tar cost calculator to compare delivered prices, freight, and landed costs for bitumen 40/50 into Bhutan—so you can budget confidently before the construction season starts.