Content Overview
Bitumen AH Grades: The 2025 Ultimate Guide for Pavement Professionals, Buyers & Specifiers
1. Executive Snapshot
Bitumen AH Grades—sometimes called asphalt binder AH, asphalt cement AH, or simply AH-bitumen—are penetration-controlled binders engineered for hot climates and high-traffic pavements. In 2024–2025 they account for about 27 % of all paving-grade bitumen traded in Asia–Pacific, with AH-70 and AH-90 dominating highway surfacing and airport aprons. Global infrastructure stimulus, tighter carbon regulations, and the rebound of tourism-driven runway projects keep demand brisk despite volatile crude markets.
2. What Exactly Are Bitumen AH Grades?
Standard & Code – “AH” derives from the Japanese Industrial Standard JIS K 2207, where grades are indexed mainly by penetration at 25 °C and dynamic viscosity at 60 °C.
Core Range – AH-50, AH-60, AH-70, AH-90, AH-100; the higher the number, the stiffer and more rut-resistant the binder.
Key Difference vs. VG & PG – Unlike viscosity-grade (VG-10, VG-30) and Superpave performance-grade (PG 64-22), AH grading links directly to both penetration and viscosity, giving contractors a quick feel for workability and high-temperature stability in a single label.
| Grade | Penetration (0.1 mm) | Viscosity @ 60 °C (Pa·s) | Softening Point (°C) | Typical Climate | Closest VG/PG Analog* |
|---|---|---|---|---|---|
| AH-50 | 60 – 80 | ≥ 120 | 42 – 48 | Temperate | VG-20 / PG 58-22 |
| AH-70 | 60 – 70 | ≥ 130 | ≥ 42 | Sub-tropical | VG-30 / PG 64-22 |
| AH-90 | 40 – 60 | ≥ 220 | ≥ 47 | Hot–humid | VG-40 / PG 70-22 |
| AH-100 | 30 – 50 | ≥ 300 | ≥ 51 | Equatorial | — (specialty) |
*Equivalence for quick bidding only; always cross-check local specs.
3. Chemistry & Rheology Behind AH Bitumen
3.1 Molecular Makeup
Bitumen is a colloidal system of asphaltenes dispersed in maltenes. In AH grades, the asphaltene-to-resin ratio is tuned through vacuum distillation and mild oxidation so the binder stays viscous during mixing yet resists permanent deformation at 60 °C wheel-tracking tests.
3.2 Viscoelastic Behavior
Dynamic Shear Rheometer (DSR) sweeps at 0.1–10 Hz show AH-90 exhibits a complex modulus (G* ) of roughly 18 kPa at 58 °C after Rolling-Thin-Film Oven (RTFO) aging—about 35 % higher than AH-70, translating to superior rut resistance on urban arterials. (ResearchGate)
3.3 Low-Temperature Performance
Cracking indices (ΔTc) for neat AH binders hover around –2 °C to –3 °C; modifiers such as SBS, crumb rubber or emerging polyethylene–C9 resin blends extend this to –6 °C without sacrificing high-temp grade. (mdpi.com)
4. Manufacturing & Quality Assurance
Feedstock Selection – Paraffinic Middle-East crudes tend to yield AH-70 efficiently; naphthenic Venezuelan crudes are favored for AH-90 due to natural high asphaltene content.
Process Route
Atmospheric & vacuum distillation
Air-blowing (195 – 230 °C, 20–50 kPa O₂)
Inline blending / polymer dosing (optional)
Testing Protocols – Routine QC follows ASTM D5 (penetration), ASTM D36 (softening point), ASTM D2171 (viscosity), and EN 12591 flash-point verification for export shipments.
| Test | Spec Limit AH-70 | Spec Limit AH-90 | Reference |
|---|---|---|---|
| Penetration 25 °C (0.1 mm) | 60–70 | 40–60 | ASTM D5 |
| Softening Point (°C) | ≥ 42 | ≥ 47 | ASTM D36 |
| Dynamic Viscosity 60 °C (Pa·s) | ≥ 130 | ≥ 220 | ASTM D2171 |
| Flash Point C.O.C (°C) | ≥ 260 | ≥ 260 | ASTM D92 |
Values compiled from 2024 export grade bulletins.
5. Mix Design & Field Performance
Plant Mixing Window – For AH-70, optimal mixing lies between 150 – 160 °C, compaction at 145 °C; AH-90 often needs 10 °C extra unless warm-mix additives lower viscosity.
Rutting Resistance – Hamburg Wheel-Track data show < 4 mm rut depth after 20 000 passes for 45 mm SMA using AH-90, meeting many airport taxiway specs.
Fatigue Life – Four-point beam fatigue indicates AH-70 mixtures reach >150 k cycles at 400 µε, making it a balanced choice for flexible pavements where low-temp cracking is a concern.
6. 2025 Market Pulse & Pricing Outlook
| Region | 2023 Avg CIF Price AH-70 (US $/t) | 2024 Q4 Price | YoY % | Drivers 2025 |
|---|---|---|---|---|
| China | 520 | 575 | +10.6 % | Belt-&-Road rail spurs |
| India | 505 | 555 | +9.9 % | Rural road package |
| Indonesia | 530 | 590 | +11.3 % | IKN new capital works |
| Kenya | 560 | 620 | +10.7 % | LAPSETT port–road links |
Forecast: Tight sulfur cap on marine fuel and OPEC+ cuts may push AH-grade premiums another 3–5 % by Q3 2025. Carbon-adjusted border taxes proposed in the EU could nudge exporters toward low-emission production routes.
7. Sustainability & Carbon-Smart Asphalt
Warm-Mix Technology – Foam, surfactant, and wax additives cut mixing temps by up to 30 °C, lowering Scope 1 emissions about 18 kg CO₂/t HMA.
Reclaimed Asphalt Pavement (RAP) – AH binders tolerate up to 30 % RAP when rejuvenating oils restore maltene fractions.
Bio-Based Modifiers – Trials in Malaysia blend 5 % bio-oil into AH-70, slashing non-renewable carbon intensity by 12 %.
Circular Economy – EU 2024 directive endorses polymer-modified AH-90 containing >7 % recycled LDPE, turning plastic waste into durable pavements.
8. Innovation Watch: From AI to Graphene
AI-Driven Binder Selection – Cloud models cross-reference climate data, axle spectra, and AH rheology to auto-suggest the most economical grade.
Graphene-Enhanced AH – 0.1 % graphene nanoplatelets raise softening point by 6 °C and double fatigue life; expected commercialization in 2026.
Self-Healing Asphalt – Micro-capsulated rejuvenators integrated into AH-70 extend service life by 40 % under Dutch field trials.
IoT Pavements – Conductive fillers in AH-90 allow winter induction-heating repairs, already piloted on Norwegian E39.
9. Practical Procurement & Handling Guide
Spec Sheet Checklist
Grade (AH-70? AH-90?)
Batch number & refinery
Viscometric curve 40–135 °C
Safety Data Sheet (SDS) compliance (GHS)
Shipping Formats – 185 kg new steel drums, 1 t jumbo bags with low-melt liners, or bulk ISO-tanks fitted with heating coils.
Storage Tips – Maintain 135 – 145 °C in vertical tanks; avoid air ingress to curb oxidation, especially for AH-50/70.
Health & Safety – Use IR thermometers; wear face shields—flash point is high, but splashes at 170 °C can cause severe burns.
Common Pitfalls – Don’t blend AH-grades with reclaimed viscosity-grade bitumen without lab confirmation; incompatibility can trigger phase separation.
10. Frequently Asked Questions
Q1. Is AH-70 equivalent to penetration grade 60/70?
In general yes. Both target 60–70 dmm penetration, but AH-70 also guarantees a minimum viscosity, giving extra assurance in hot-mix stability.
Q2. Which grade fits desert expressways?
AH-90 or even AH-100 combined with warm-mix agents offers the rut-resistance needed for 60 °C mid-day surface temperatures.
Q3. Can I use AH-bitumen in polymer-modified asphalt (PMA)?
Certainly—AH-70 base binder blended with 3 % SBS forms PMA meeting PG 76-16 performance.
Q4. How do I verify genuine AH spec on arrival?
Run spot penetration and softening tests; cross-check viscosity @ 60 °C. Any variance > ±5 % points to adulteration.
11. Key Takeaways
Bitumen AH Grades give contractors an intuitive, dual-parameter handle on hot-climate performance.
AH-70 balances workability and durability; AH-90 and AH-100 push the envelope for extreme heat and heavy loads.
2025’s market favors sustainable binders—warm-mix, recycled plastics, and AI-optimized blends are moving from pilot to mainstream.
Smart procurement—verifying specs, managing temperature, and integrating RAP—turns these binders into pavements that last and pay back faster.
Staying ahead means pairing the right AH grade with modern mix design, low-carbon additives, and data-driven asset management. Do that, and your roads, runways, and revenue streams will stand the test of climate, traffic, and time.
Prepared by the PetroNaft Co. research team.
