Oxidized bitumen 90/40 is the most flexible grade in the blown range that still holds a useful softening point. At 85 to 95 °C softening point with 35 to 45 dmm penetration, it sits at the soft corner of what air blowing produces. That makes it the membrane grade for temperate and cool climates, and the wrong choice for a roof in the Gulf. Where 105/35 is specified for heat, 90/40 is specified for movement.
RAHA Gilsonite supplies oxidized bitumen 90/40 against ASTM D312, BS EN 13304:2009 or a buyer’s own specification. This page covers the specification, why the high penetration is the point of the grade rather than a weakness, the melting and coating temperatures, and how to decide between 90/40 and the grades either side of it.
What is oxidized bitumen 90/40?
Oxidized bitumen, also called blown bitumen or blown asphalt, is produced by blowing air through hot penetration grade bitumen at around 240 to 260 °C. Oxygen reacts with the maltene fraction and converts it toward asphaltenes. The binder becomes harder, the softening point climbs and the penetration falls.
Reading the designation
The grade name reads softening point over penetration. In oxidized bitumen 90/40, the 90 is the ring-and-ball softening point in degrees Celsius and the 40 is the penetration at 25 °C in tenths of a millimetre. Under BS EN 13304:2009, oxidised grades are expressed as multiples of 5, so 90/40 is a standard-defined grade within that European framework.
The lightly blown grade
90/40 has been blown less far than the harder grades. The asphaltene network has formed enough to raise the softening point about 40 °C above the feedstock, but not so far that the material loses its ability to bend. At 40 dmm the binder is still recognisably viscoelastic rather than resinous.
That is deliberate and it is what the grade is for. A membrane sheet has to be rolled at the factory, transported on a pallet, unrolled on a roof in winter and folded at the upstand. A binder that cracks under any of those steps fails before the roof ever sees a summer.
The trade-off in one line. Every degree of softening point you gain by blowing further, you pay for in penetration. 90/40 sits at the flexible end of that curve. It will not survive a dark roof at 90 °C surface temperature, but it will survive a European or East Asian winter without cracking at the fold.
Oxidized bitumen 90/40 specification
| Property | Unit | Specification | Typical result | Test method |
|---|---|---|---|---|
| Softening point (ring & ball) | °C | 85–95 | 90 | ASTM D36 / EN 1427 |
| Penetration @25 °C, 100 g, 5 s | dmm | 35–45 | 40 | ASTM D5 / EN 1426 |
| Loss on heating | wt % | 0.5 max | 0.2 | ASTM D6 |
| Flash point (Cleveland open cup) | °C | 240 min | 265 | ASTM D92 |
| Solubility in trichloroethylene | wt % | 99 min | 99.5 | ASTM D2042 |
| Specific gravity @25 °C | — | 1.00–1.05 | 1.02 | ASTM D70 |
| Ductility @25 °C | cm | 3 min | 3–6 | ASTM D113 |
| Ash content | wt % | 0.5 max | 0.2 | ASTM D2939 |
| Spot test | — | Negative | Negative | AASHTO T102 |
Unlike the hard blown grades, ductility is a genuine specification limit for 90/40 rather than an informational figure. For membrane production it is the single most useful number on the certificate, because it predicts whether the finished sheet will crack when folded. Test methods are maintained by ASTM International.
Applications of oxidized bitumen 90/40
Everything below involves a product that moves, bends or is laid over a substrate that expands and contracts. That is what distinguishes 90/40 from the harder grades.
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Roofing felt and membrane
The dominant use. Coating and impregnation compound for bitumen felt and torch-on membrane sold into temperate and cool markets — Europe, northern China, Korea, Japan, and highland regions elsewhere.
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Damp proof course sheet
DPC manufacture, where the sheet is rolled tight at the factory and unrolled cold on site. Higher penetration is essential here.
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Built-up roofing systems
Bonding and mopping compound between membrane layers in multi-ply roofing, applied hot and required to stay flexible after cooling.
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Below-grade waterproofing
Foundation and basement tanking on substrates likely to settle or move. Ground temperature is stable, so heat resistance matters less than flexibility.
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Expansion joint sealing
Pourable sealants for joints that open and close seasonally, where a hard grade would crack in the first winter cycle.
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Construction adhesives
Board, panel and insulation bonding compounds in temperate climates, and general bituminous adhesive work.
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Sound damping compounds
Automotive and appliance damping pads applied to panels that vibrate. A brittle compound delaminates; 90/40 stays bonded.
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Cold and temperate pipe wrapping
Wrapping tape and coating compounds for pipe laid in cooler ground, where the pipe flexes during installation.
Where 90/40 is the wrong grade
Do not specify 90/40 for roofing in hot climates. A dark membrane surface in the Gulf, North Africa, South Asia or equatorial Africa routinely exceeds 80 °C in summer, which is inside the softening range of this grade. The sheet softens, flows at the laps and slides on a pitched roof. For those markets use 105/35 or 115/15.
Equally, do not use it for pipe coating enamel, sealing compounds on static joints, or any industrial compound that must resist creep under sustained load. Those belong to 105/15, 90/10 or harder.
How 90/40 compares with the other oxidized grades
| Grade | Softening point | Penetration | Class | Principal use |
|---|---|---|---|---|
| 150/5 | 145–155 °C | 0–10 dmm | Hardest | Electrical compounds, battery sealing, pipe enamel, rubber |
| 115/15 | 110–120 °C | 10–20 dmm | Hard | Waterproofing, adhesives, sealing, pipe coating |
| 105/35 | 100–110 °C | 30–40 dmm | Medium | Membrane for hot climates. The direct alternative to 90/40 |
| 105/15 | 100–110 °C | 10–20 dmm | Hard | Sealing, jointing, industrial mastics |
| 95/25 | 90–100 °C | 20–30 dmm | Medium | Roofing membrane, damp proofing. Firmer than 90/40 |
| 90/40 | 85–95 °C | 35–45 dmm | Softer | Roofing felt and membrane in temperate and cool climates |
| 90/15 | 85–95 °C | 10–20 dmm | Medium | Same softening point, far harder. Adhesive and sealing work |
| 90/10 | 85–95 °C | 5–15 dmm | Hard | Pipe coating, industrial compounds |
| 85/40 | 80–90 °C | 35–45 dmm | Softer | Membrane and DPC in cold climates. Softest of the flexible grades |
| 85/25 | 80–90 °C | 20–30 dmm | Medium | The volume roofing grade worldwide |
| 75/35 | 70–80 °C | 30–40 dmm | Softest | Damp proofing, low-temperature climates |
| 75/25 | 70–80 °C | 20–30 dmm | Softest | General waterproofing, jointing |
The full range is listed on our oxidized bitumen grades page.
The three grades that share 90 °C
90/40, 90/15 and 90/10 all sit in the same 85 to 95 °C softening band, and they are not substitutes. The penetration runs from 40 dmm down to 10 — a factor of four. Ordering by softening point alone across these three is the most direct route to a failed batch.
| 90/40 | 90/15 | 90/10 | |
|---|---|---|---|
| Penetration | 35–45 dmm | 10–20 dmm | 5–15 dmm |
| Behaviour at ambient | Flexible, folds without cracking | Firm, limited flex | Hard, fractures |
| Suits membrane | Yes | Marginal | No |
| Suits static sealing | Only where the joint moves | Yes | Yes |
| Suits pipe coating | Wrapping tape only | Yes | Yes — the usual choice |
90/40 against 85/25 and 105/35
85/25 is the world’s volume roofing grade and the natural comparison. It is slightly lower in softening point but substantially harder. 90/40 gives more flexibility and a little more heat margin, which suits markets with genuine winters and mild summers. Where budget dominates and the climate is average, 85/25 is the default.
105/35 is the hot-climate answer. It holds a similar penetration to 90/40 but adds 15 °C of softening point. If your membrane is sold into the Gulf, North Africa or South Asia, that margin is the difference between a working roof and a warranty claim.
Melting and coating temperatures
| Operation | Temperature | Notes |
|---|---|---|
| Melting | 160–185 °C | Indirect heating. Lower than the hard grades — the material melts readily |
| Pumping | 170–190 °C | Heat traced lines. Sets in cold pipework |
| Coating / application | 180–205 °C | Membrane lines usually run at the upper end for even film thickness |
| Absolute maximum | 220 °C | Lower ceiling than the hard grades. Above this the penetration drops quickly |
| Hot holding | Limit to a working shift | Prolonged holding continues the blowing reaction and hardens the grade |
This grade is the easiest to ruin by overheating. The whole reason to buy 90/40 rather than 90/15 is the 40 dmm penetration. Hold it at 220 °C across a long shift and you can drop several points, at which stage you have paid for 90/40 and are coating with something closer to 90/30. Log the tank temperature and test the penetration on the finished sheet, not only on the incoming bags.
Safety
The flash point is 240 °C minimum, so there is margin against the working range, but fume generation and thermal burn risk are real. If the material foams, spits or crackles as it heats, water is present — stop heating rather than trying to drive it off. Handling guidance is published by Eurobitume and the Asphalt Institute.
Packing, storage and shipping
| Packing | Unit weight | Per 20′ container | Notes |
|---|---|---|---|
| Kraft paper bag | 25 kg | Up to 25 MT palletised | Most common. Meltable bag options available so the bag goes into the melter |
| PP bag | 25 kg | Up to 25 MT palletised | Palletised and shrink wrapped |
| Carton box | 25 kg | Up to 22 MT | Recommended for this grade. Better protection against block deformation |
| New steel drum | 180–190 kg | 80 drums ≈ 15 MT | Requires cutting or a drum melter at destination |
Storage and shelf life
Two to three years in sealed packing kept dry and out of direct sun. Because the material is already blown there is little left for atmospheric oxygen to react with, so chemical ageing runs slowly.
Storage discipline matters more for 90/40 than for any other blown grade. At 40 dmm the blocks are soft, and a stack left in tropical sun will fuse into a single mass that has to be broken up before it can be charged into a melter. Container temperatures on a long sea leg through the Red Sea routinely reach 60 to 70 °C, which is close enough to the softening range to matter. Limit stacks to two tiers, keep pallets shaded, and unload promptly on arrival rather than leaving containers standing in a yard.
Customs classification
The grade falls under HS 2713.20, petroleum bitumen. Bagged material at ambient temperature is generally not classified as dangerous goods for sea carriage, although most shipping lines and destination customs still require the safety data sheet with the booking. Note that gilsonite and other natural bitumen fall under a different heading.
Quality control and certification
Every shipment leaves with a batch certificate of analysis stating the lot number, the production date, the standard tested against and each test with its method and measured result. We accept third-party inspection at loading by SGS, Bureau Veritas, Intertek or any surveyor named in your contract.
What to check for this grade
Read the penetration and the ductility together. For 90/40 both are genuine limits and both predict how the finished sheet will behave. A batch that arrives at 94 °C softening point with 36 dmm penetration technically passes, but it is at the hard corner and will behave more like 95/25 in a coating line. If your process is sensitive, contract to a narrower band — for example 88 to 92 °C with 38 to 43 dmm — rather than accepting the full specification range.
Frequently asked questions about oxidized bitumen 90/40
What does 90/40 mean in oxidized bitumen?
The first number is the ring-and-ball softening point in degrees Celsius, so approximately 90 °C. The second is the penetration at 25 °C in tenths of a millimetre, so approximately 40 dmm. The specification runs 85–95 °C for softening point and 35–45 dmm for penetration.
What is oxidized bitumen 90/40 used for?
Principally roofing felt and membrane manufacture for temperate and cool climates, plus damp proof course sheet, built-up roofing compounds, below-grade waterproofing, expansion joint sealants, construction adhesives, sound damping compounds and pipe wrapping. All of these involve a product that bends or a substrate that moves.
Can 90/40 be used for roofing in hot climates?
No. A dark membrane surface in the Gulf, North Africa, South Asia or equatorial Africa routinely exceeds 80 °C in summer, which is inside this grade’s softening range of 85 to 95 °C. The sheet softens, flows at the laps and can slide on a pitched roof. Use 105/35 or 115/15 for those markets.
What is the difference between 90/40 and 90/15?
They share the same softening point band of 85 to 95 °C but the penetration differs by a factor of two to three — 35 to 45 dmm against 10 to 20. 90/40 folds without cracking and suits membrane; 90/15 is much firmer and belongs in adhesive and sealing work. Ordering by softening point alone across the 90-series grades is a common and expensive mistake.
What is the difference between 90/40 and 85/25?
85/25 is the world’s volume roofing grade, slightly lower in softening point but substantially harder at 20 to 30 dmm. 90/40 gives more flexibility and a little more heat margin, which suits markets with real winters and mild summers. Where cost dominates and the climate is average, 85/25 is usually the default choice.
What temperature do I melt oxidized bitumen 90/40 at?
Melt at 160 to 185 °C, pump at 170 to 190 °C and coat at 180 to 205 °C, using indirect heating. Do not exceed 220 °C — the ceiling is lower than for hard grades, and overheating drops the penetration that makes this grade worth buying.
Is oxidized bitumen 90/40 the same as blown asphalt 90/40?
Yes. Oxidized bitumen, blown bitumen and blown asphalt all describe the same product — penetration grade bitumen air-blown at high temperature to raise the softening point and reduce the penetration. The naming varies by region rather than by product.
Does 90/40 have a ductility requirement?
Yes, typically 3 cm minimum at 25 °C, and it is a genuine specification limit rather than an informational figure as it is for the hard grades. For membrane production it is the most useful number on the certificate, because it predicts whether the finished sheet will crack when folded.
How should oxidized bitumen 90/40 be stored?
On pallets, under cover, no more than two tiers high, out of direct sun. Storage discipline matters more for this grade than for the harder ones because at 40 dmm the blocks are soft enough to fuse into a single mass under stacking pressure in tropical heat. Shelf life is two to three years in sealed packing, and containers should be unloaded promptly on arrival rather than left standing in a yard.
What is the HS code for oxidized bitumen?
HS 2713.20, petroleum bitumen, which covers all oxidized and penetration grades. National tariffs add further digits, so confirm the full code with your customs broker. Gilsonite and other natural bitumen fall under a different heading.
What is the minimum order quantity?
One full 20′ container, roughly 22 to 25 MT depending on packing. Mixed grades in one shipment are accepted provided each grade reaches one full container. Loading is from Jebel Ali Port in Dubai or Iskenderun Port in Turkey, on FOB, CFR or CIF terms.
Can you supply against a tighter specification?
Yes. Where your coating line is sensitive to where the material sits within the 85–95 °C and 35–45 dmm windows, we can contract to a narrower band. Say so at the enquiry stage rather than after the first shipment, since it affects which production batch is allocated.
Related grades and technical pages
Adjacent grades: oxidized bitumen 85/40 for colder climates, 95/25 and 85/25 for firmer membrane, 105/35 for hot-climate roofing, and 90/15 or 90/10 where the same softening point is needed in a harder binder. The complete list is on the oxidized bitumen grades page.
Where a compound needs additional hardness, gloss or a higher softening point than blown bitumen alone can deliver, gilsonite is frequently blended in — see gilsonite specification, gilsonite in paint and gilsonite in asphalt. For the difference between air-blown and naturally occurring hard bitumen, see natural bitumen.
Request a quotation for oxidized bitumen 90/40
Send us the quantity, packing, discharge port and the specification your contract names. Tell us the climate your finished membrane will serve and we will confirm whether 90/40 is right or whether 85/25 or 105/35 suits better. Batch certificate of analysis with every shipment, third-party inspection accepted at loading.
Dubai: No. 2305, Burlington Tower, Business Bay — +971 4 566 4998
Ankara: Karşıyaka District, 749 Street No. 30, Gölbaşı 06830 — +90 312 544 5481
Isfahan: Second Floor, Navab Complex, Navab Safavi St
