Oxidized bitumen 90/15 is the middle grade of the 90 series, and middle grades are usually the ones buyers understand least. It is firmer than 90/40 and softer than 90/10 — too rigid for membrane, not hard enough for pipe coating enamel. What it is good at is the work that sits between those two: bituminous adhesives, sealing compounds, mastics and general waterproofing where a little flexibility helps but creep resistance still matters.
RAHA Gilsonite supplies oxidized bitumen 90/15 against ASTM D312, BS EN 13304:2009 or a buyer’s own specification, with a batch certificate of analysis issued before loading. This page sets out the specification, where the grade genuinely belongs, the melting and application temperatures, and how it compares with the two grades either side of it in the same softening band.
What is oxidized bitumen 90/15?
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 90/15, the 90 is the ring-and-ball softening point in degrees Celsius and the 15 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 90/15 is a standard-defined grade within that European framework.
Why a middle grade exists at all
It would be reasonable to ask why anyone needs a grade between 90/10 and 90/40 when both extremes are available. The answer is that a large share of bituminous work is neither purely static nor genuinely flexible.
A sealing compound in a construction joint sees small seasonal movement — not enough to need 40 dmm, but enough that 10 dmm cracks. An adhesive bonding insulation board must hold under its own weight in summer without creeping, yet tolerate slight substrate movement. A mastic filling a duct penetration needs to stay put but should not shatter if the duct is knocked.
90/15 covers that middle ground. It is not a compromise grade in the sense of being worse at everything — it is the correct specification for a genuinely intermediate requirement.
How to know if 90/15 is what you need. Ask what happens to the compound in service. If it will be rolled, folded or laid over something that expands and contracts visibly, you need 90/40 or softer. If it sits under sustained load and never moves, 90/10 resists creep better and usually costs less. If the honest answer is “it moves a little”, 90/15 is the grade.
Oxidized bitumen 90/15 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 | 10–20 | 15 | ASTM D5 / EN 1426 |
| Loss on heating | wt % | 0.5 max | 0.2 | ASTM D6 |
| Flash point (Cleveland open cup) | °C | 245 min | 268 | ASTM D92 |
| Solubility in trichloroethylene | wt % | 99 min | 99.5 | ASTM D2042 |
| Specific gravity @25 °C | — | 1.00–1.06 | 1.03 | ASTM D70 |
| Ductility @25 °C | cm | Report | 1.5–3 | ASTM D113 |
| Ash content | wt % | 0.5 max | 0.2 | ASTM D2939 |
| Spot test | — | Negative | Negative | AASHTO T102 |
Ductility sits at the threshold where the figure starts to carry meaning again. At 15 dmm the material still stretches slightly before fracturing, so the reported value is a useful indicator for adhesive and sealing applications even though it is not a pass or fail limit. Test methods are maintained by ASTM International.
Applications of oxidized bitumen 90/15
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Bituminous adhesives
The primary use. Bonding compounds for insulation board, membrane laying and panel fixing, where the adhesive must hold under load without creeping but tolerate slight substrate movement.
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Sealing and jointing compounds
Construction joints, duct penetrations and tank seams that see modest seasonal movement rather than genuine expansion.
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General waterproofing compounds
Hot-applied waterproofing on rigid substrates, tanking and protective coatings for below-grade concrete.
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Industrial mastics
Filling and levelling compounds for plant floors, machinery bases and industrial substrates carrying moderate load.
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Roofing primer and base layer
Priming and bonding beneath membrane, distinct from the membrane coating itself which needs a softer grade.
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Construction compounds
General bituminous fillers, packing compounds and site-mixed formulations across building work.
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Pipe wrapping compounds
Wrapping tape formulations and secondary coating layers, where the tape must conform to the pipe surface.
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Cable and electrical filling
Jointing and filling compounds for cable runs and enclosures operating at moderate temperature.
Where 90/15 is the wrong grade
Do not use it as the coating compound for roofing felt or torch-on membrane. At 15 dmm the sheet cracks at the fold. Membrane needs 90/40, 85/25 or 105/35 depending on climate.
Do not use it for pipe coating enamel on buried line either. 90/10 resists creep under soil pressure substantially better and costs less. And for anything exposed to genuinely high service temperature, the 85 to 95 °C softening band is inadequate — move to 105/15 or 115/15.
The 90 series compared
These three share the same softening point band and differ only in penetration. That difference decides everything about how they behave.
| 90/10 | 90/15 | 90/40 | |
|---|---|---|---|
| Penetration | 5–15 dmm | 10–20 dmm | 35–45 dmm |
| Behaviour at ambient | Hard, fractures under bending | Firm, slight give before fracture | Flexible, folds without cracking |
| Creep resistance | Highest | Good | Limited |
| Tolerates small movement | No | Yes | Yes, and large movement too |
| Suits membrane coating | No | No | Yes |
| Suits pipe coating enamel | Yes — the standard choice | Secondary layers and wrapping only | Wrapping tape only |
| Suits adhesives | Rigid bonding only | Yes — the natural fit | Where the bond must flex |
| Melting temperature | 175–200 °C | 170–195 °C | 160–185 °C |
The overlap between 90/10 and 90/15 is worth noting: both specifications include the 10 to 15 dmm range. A batch of 90/10 at the soft corner and a batch of 90/15 at the hard corner can be nearly identical material. If your process is sensitive, this is a reason to contract on measured values rather than grade name alone.
90/15 against 105/15
105/15 shares the same penetration band but carries 15 °C more softening point. Where the compound will see service temperature above about 60 °C — exposed installations in hot climates, plant rooms, machinery enclosures — 105/15 is the safer specification. Where service temperature is moderate, 90/15 does the same job at a lower melting temperature and a lower price.
How 90/15 compares with the full oxidized range
| 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 and sealing in hot climates |
| 105/35 | 100–110 °C | 30–40 dmm | Medium | Membrane for hot climates |
| 105/15 | 100–110 °C | 10–20 dmm | Hard | The hot-climate equivalent of 90/15 |
| 95/25 | 90–100 °C | 20–30 dmm | Medium | Membrane and damp proofing in warm markets |
| 90/40 | 85–95 °C | 35–45 dmm | Softer | Membrane for temperate and cool climates |
| 90/15 | 85–95 °C | 10–20 dmm | Medium | Adhesives, sealing compounds, mastics, general waterproofing |
| 90/10 | 85–95 °C | 5–15 dmm | Hard | Pipe coating, cable filling, tank lining |
| 85/40 | 80–90 °C | 35–45 dmm | Softer | Membrane and DPC in cold climates |
| 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.
Melting and application temperatures
| Operation | Temperature | Notes |
|---|---|---|
| Melting | 170–195 °C | Indirect heating only. Melt the full charge and homogenise before drawing off |
| Pumping | 180–200 °C | Lines and pumps must be heat traced or the material will set in them |
| Application / blending | 185–210 °C | Adhesive and mastic work usually runs at the lower end; sealing compounds higher |
| Absolute maximum | 225 °C | Above this the material cokes, fumes heavily and the softening point drifts |
| Hot holding | Limit to a working shift | Prolonged holding continues the blowing reaction and hardens the grade toward 90/10 |
The hot-holding warning matters here more than usual. 90/15 and 90/10 overlap in the 10 to 15 dmm range, so a batch of 90/15 held hot across a long shift can drift into what is effectively 90/10 territory. If you chose 90/15 specifically because you needed the slight flexibility, that drift removes it. Melt per batch where the process allows.
Safety
The flash point is 245 °C minimum, so there is margin against the working range, but fume generation and thermal burn risk are real at these temperatures. Because bitumen is a poor conductor of heat, the melting phase must be controlled to prevent localised overheating. 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 | Better protection for long transit and rough handling |
| 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 fully blown there is little left for atmospheric oxygen to react with, so chemical ageing runs slowly.
At 15 dmm the blocks stay firm enough that stack fusion is a minor concern rather than a real risk, unlike the softer grades. Standard practice still applies: pallets, under cover, no more than two tiers, batch number filed with the certificate of analysis.
Customs classification
The grade falls under HS 2713.20, petroleum bitumen. Bagged and drummed 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
Because 90/15 overlaps with 90/10 at the bottom of its range and approaches 95/25 territory at the top, the measured penetration matters more than the grade name. A batch at 11 dmm behaves like a hard grade; one at 19 dmm behaves closer to a medium one. If your formulation depends on the intermediate character that makes 90/15 worth specifying, contract to a narrower band such as 14 to 17 dmm rather than accepting the full window.
Frequently asked questions about oxidized bitumen 90/15
What does 90/15 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 15 dmm. The specification runs 85–95 °C for softening point and 10–20 dmm for penetration.
What is oxidized bitumen 90/15 used for?
Principally bituminous adhesives and bonding compounds, sealing and jointing compounds, general waterproofing on rigid substrates, industrial mastics, roofing primers and base layers, pipe wrapping compounds and cable filling. All of these need creep resistance combined with tolerance for small movement.
What is the difference between 90/15, 90/10 and 90/40?
They share the same softening point band of 85 to 95 °C and differ only in penetration — 10 to 20 dmm for 90/15, 5 to 15 for 90/10 and 35 to 45 for 90/40. 90/10 is hardest and suits pipe coating; 90/40 is flexible and suits membrane; 90/15 sits between them and suits adhesives, sealing compounds and mastics where the compound moves a little but must not creep.
Can oxidized bitumen 90/15 be used for roofing membrane?
Not as the coating compound. At 15 dmm the sheet cracks at the fold and fails at the lap. Membrane coating needs 90/40, 85/25 or 105/35 depending on climate. 90/15 can be used for the primer or base layer beneath the membrane, which is a different function.
Should I choose 90/15 or 105/15?
They share the same penetration band, so both behave similarly at ambient temperature, but 105/15 carries 15 °C more softening point. Where the compound will see service temperature above about 60 °C — exposed installations in hot climates, plant rooms, machinery enclosures — specify 105/15. Where service temperature is moderate, 90/15 does the same job at a lower melting temperature and a lower price.
What temperature do I melt oxidized bitumen 90/15 at?
Melt at 170 to 195 °C, pump at 180 to 200 °C and apply at 185 to 210 °C, using indirect heating. Do not exceed 225 °C. Avoid prolonged hot holding, since it hardens the grade toward 90/10 and removes the slight flexibility that makes 90/15 worth specifying.
Is oxidized bitumen 90/15 the same as blown asphalt 90/15?
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.
Why do the 90/10 and 90/15 specifications overlap?
Both include the 10 to 15 dmm range, which is a feature of how oxidised grades are defined in multiples of 5 with overlapping tolerance windows. In practice it means a batch of 90/10 at the soft corner and a batch of 90/15 at the hard corner can be nearly identical material. Where a process is sensitive, contract on measured values rather than grade name alone.
What is the shelf life of oxidized bitumen 90/15?
Two to three years in sealed packing kept dry, on pallets and out of direct sun. Chemical ageing is slow because the material is already blown. At 15 dmm the blocks stay firm enough that stack fusion is a minor concern rather than a real risk, unlike the softer grades.
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, and for this grade it is worth asking. A batch at 11 dmm behaves like a hard grade and one at 19 dmm closer to a medium one. If your formulation depends on the intermediate character that makes 90/15 worth specifying, contract to a narrower band such as 14 to 17 dmm. Say so at the enquiry stage, since it affects which production batch is allocated.
Related grades and technical pages
Adjacent grades: oxidized bitumen 90/10 for pipe coating and static work, 90/40 for membrane, 105/15 where the same hardness is needed at higher service temperature, and 95/25 for a slightly softer medium grade. 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 90/15
Send us the quantity, packing, discharge port and the specification your contract names. Tell us what the compound has to do in service — whether it moves, how hot it gets — and we will confirm whether 90/15 is right or whether 90/10, 90/40 or 105/15 fits 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
