Oxidized bitumen 85/25 is the most widely produced blown grade in the world. If a roofing membrane factory anywhere buys one oxidised grade, this is usually it. That popularity is deserved — it balances heat resistance and workability at the lowest cost in the range — but it also means 85/25 gets specified by default in markets where it does not belong. This page covers what it is genuinely good at, and the one climate condition that should make you order something else.
RAHA Gilsonite supplies oxidized bitumen 85/25 against ASTM D312, BS EN 13304:2009, BS 3690, DIN 1995 or a buyer’s own specification, with a batch certificate of analysis issued before loading. This page sets out the specification, the production process, the applications the grade genuinely covers, and an honest assessment of where it should be replaced by something harder.
What is oxidized bitumen 85/25?
Oxidized bitumen 85/25, also called blown asphalt 85/25 or blown bitumen 85/25, is produced by blowing hot compressed air through penetration grade bitumen at elevated temperature. The process raises the softening point and reduces the penetration, producing a harder, more heat-resistant binder than the feedstock it started from.
Reading the designation
The grade name reads softening point over penetration.
| Number | What it measures | Meaning |
|---|---|---|
| 85 | Ring-and-ball softening point, °C | The temperature at which the binder transitions from solid to pliable |
| 25 | Penetration at 25 °C, dmm | A standard needle sinks 2.5 mm under defined test conditions |
Under BS EN 13304:2009, oxidised grades are expressed as multiples of 5, so 85/25 is a standard-defined grade within that European framework. Compared with softer grades such as 75/35, it is harder and more heat resistant. Compared with 105/35 it is softer and cheaper, and it holds substantially less heat margin.
Why 85/25 became the volume grade
Three reasons, and they are worth understanding because they explain both its strengths and its limits.
It is the cheapest useful blown grade. Blowing costs energy and time. 85/25 requires the least of both among grades that still deliver meaningful heat resistance, so it sits at the bottom of the price ladder.
It suits the largest population of buyers. Most of the world’s roofing membrane is installed in temperate climates — Europe, temperate Asia, highland Africa, the cooler parts of the Americas. In those markets 85/25 is entirely adequate.
It is workable on standard equipment. Coating lines built around 85/25 run at moderate temperature, which keeps fuel cost and fume generation down compared with the harder grades.
The problem with a default grade. Because 85/25 is what most factories run and most traders quote, it gets specified into markets where the climate is wrong for it. A membrane sold into the Gulf, North Africa or South Asia coated with 85/25 will soften at the laps in its first summer. The failure is predictable and it is the single most common oxidised bitumen specification error in the trade.
Oxidized bitumen 85/25 specification
| Property | Unit | Specification | Typical result | Test method |
|---|---|---|---|---|
| Softening point (ring & ball) | °C | 80–90 | 85 | ASTM D36 / EN 1427 |
| Penetration @25 °C, 100 g, 5 s | dmm | 20–30 | 25 | ASTM D5 / EN 1426 |
| Ductility @25 °C | cm | 2.0 min | 2.5–4 | ASTM D113 |
| Flash point (Cleveland open cup) | °C | 250 min | 265 | ASTM D92 |
| Solubility in trichloroethylene | wt % | 99 min | 99.5 | ASTM D2042 |
| Loss on heating (163 °C, 5 h) | wt % | 0.2 max | 0.1 | ASTM D6 |
| Density @25 °C | g/cm³ | 1.01–1.06 | 1.03 | ASTM D70 |
| Ash content | wt % | 0.5 max | 0.2 | ASTM D2939 |
| Spot test | — | Negative | Negative | AASHTO T102 |
Solubility is tested in trichloroethylene to ASTM D2042. Older specifications sometimes name carbon disulphide, but that solvent has been withdrawn from routine use on fire-safety grounds and a certificate quoting it should be queried. Test methods are maintained by ASTM International. Where a project specification differs from the values above, send us the specification rather than the grade name and we will confirm what meets it.
Production process
| Stage | What happens | Why it matters |
|---|---|---|
| 1. Feedstock selection | Penetration grade 60/70 or 80/100 from vacuum distillation residue | Crude composition determines whether the blown product holds a stable 85/25 profile |
| 2. Pre-heating | Charge heated to 240–270 °C in the blowing tower | Temperature uniformity ensures consistent asphaltene formation across the batch |
| 3. Air injection | Compressed air injected continuously through perforated pipes | Oxygen reacts with the maltene fraction, raising molecular weight and rigidity |
| 4. QC monitoring | Softening point and penetration tested through the blowing cycle | Production stops only when both land inside the target window simultaneously |
| 5. Packing and inspection | Decanted under temperature control into bags, cartons or drums | Third-party inspection verifies quality and quantity at loading |
Applications of oxidized bitumen 85/25
-
Roofing membranes and felt
- Flat and low-slope roofing systems
- APP and SBS modified membrane base
- Built-up roofing (BUR) systems
- Bituminous roofing felt
-
Waterproofing systems
- Basement and foundation waterproofing
- Tunnels and underground parking
- Bridge deck waterproofing
- Retaining walls and podium decks
-
Pipe coating
- Oil and gas transmission pipeline
- Water distribution networks
- Sewage and drainage systems
-
Bituminous paints and primers
- Steel structure protection
- Marine and offshore coatings
- Industrial tanks and vessels
-
Sound deadening and damping
- Automotive underbody coatings
- Sound insulation pads
- Vibration damping components
-
Electrical cable compounds
- High-voltage underground cable impregnation
- Armoured cable filling
- Joint and termination boxes
-
Construction adhesives
- Membrane bonding compounds
- Board and insulation lamination
- General bituminous mastics
-
Damp proof course
- DPC sheet manufacture
- Damp proof membrane
- Below-grade barrier layers
The climate question: when 85/25 is not enough
This is the section most supplier pages leave out, and it is the one that decides whether a membrane performs.
A dark roof surface in direct sun runs roughly 30 to 35 °C above the ambient air temperature. Work backwards from the softening point and you get a usable ambient limit.
| Peak ambient | Approx. roof surface | 85/25 suitable? | Recommended grade |
|---|---|---|---|
| Up to 35 °C | 65–70 °C | Yes | 85/25 — the correct and cheapest choice |
| 35–42 °C | 70–77 °C | Marginal | 85/25 acceptable on shaded or light-coloured surfaces; 95/25 safer |
| 42–48 °C | 77–83 °C | No | 95/25 or 105/35 |
| Above 48 °C | Above 83 °C | No | 105/35 or 115/15 |
The failure mode when the grade is too soft is consistent: the sheet softens, flows at the laps, bleeds through the surfacing, and on a pitched roof it can slide. It shows up in the first hot season and it is not repairable without relaying.
And the opposite case
85/25 also has a cold limit that gets less attention. Below about 5 °C, a sheet coated with 85/25 becomes difficult to unroll and prone to cracking at the fold. For markets with genuine winters — Russia, the Baltics, Scandinavia, northern China — 85/40 or 90/40 carry roughly double the penetration and handle winter installation properly.
85/25 is the right grade for the temperate middle. It is not a universal grade, despite being sold as one.
How 85/25 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 in hot climates |
| 105/35 | 100–110 °C | 30–40 dmm | Medium | Membrane for hot climates — the Gulf and South Asia answer |
| 105/15 | 100–110 °C | 10–20 dmm | Hard | Sealing, jointing, industrial mastics |
| 95/25 | 90–100 °C | 20–30 dmm | Medium | Same hardness as 85/25 with 10 °C more heat margin |
| 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 |
| 90/10 | 85–95 °C | 5–15 dmm | Hard | Pipe coating, cable filling, tank lining |
| 85/40 | 80–90 °C | 35–45 dmm | Softer | Cold-climate membrane and winter installation |
| 85/25 | 80–90 °C | 20–30 dmm | Medium | The volume roofing grade for temperate climates |
| 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 most often confused with 85/25
| 85/25 | 95/25 | 85/40 | |
|---|---|---|---|
| Softening point | 80–90 °C | 90–100 °C | 80–90 °C |
| Penetration | 20–30 dmm | 20–30 dmm | 35–45 dmm |
| What differs | The baseline | Same hardness, more heat margin | Same heat margin, more flexibility |
| Choose it when | Temperate climate, cost matters | Summers are hot but not extreme | Winters are cold and installation is seasonal |
| Coating temperature | 170–195 °C | 185–210 °C | 175–200 °C |
Advantages of oxidized bitumen 85/25
-
Cost efficiency
The lowest-priced blown grade that still delivers meaningful heat resistance. On high-volume membrane production, that difference compounds.
-
Balanced properties
Enough hardness for load and enough flexibility for handling in temperate conditions — the reason it became the default.
-
Weathering resistance
UV stable and dimensionally reliable through normal temperate seasonal cycling.
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Strong adhesion
Bonds well to concrete, metal, glass fibre and polyester carrier fabrics.
-
Water impermeability
A reliable moisture barrier, which is the fundamental requirement in every application it serves.
-
Chemical resistance
Resistant to acids, alkalis and aggressive soils, suiting below-grade and industrial use.
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Moderate working temperature
Coats at 170–195 °C, lower than the harder grades, reducing fuel use and fume generation.
-
Wide equipment compatibility
Most existing coating lines are configured for it, so no process change is needed.
Melting and coating temperatures
| Operation | Temperature | Notes |
|---|---|---|
| Melting | 160–185 °C | Indirect heating. Melt the full charge and homogenise before drawing off |
| Pumping | 170–190 °C | Heat traced lines. Sets quickly in cold pipework |
| Coating / application | 170–195 °C | Membrane lines typically run at the upper end for even film thickness |
| Absolute maximum | 215 °C | Above this the material cokes and the softening point drifts upward |
| Hot holding | Limit to a working shift | Prolonged holding continues the blowing reaction and hardens the grade |
Safety
The flash point is 250 °C minimum, giving reasonable margin against the working range. 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 and storage
| Package type | Net weight | Details | Per 20′ container |
|---|---|---|---|
| Kraft paper bag | 25 kg | Multi-layer, moisture resistant, meltable options available | Up to 25 MT palletised |
| Carton box | 25 kg | With polyethylene liner. Better protection on long transit | Up to 22 MT |
| Steel drum | 180 kg | New, sealed, stackable | 80 drums ≈ 14.4 MT |
| Jumbo bag | 1,000 kg | For bulk orders where handling equipment exists | Up to 22 MT |
| Melt pour | Bulk | Available on request for buyers with heated facilities | By arrangement |
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 25 dmm the blocks are firm enough that stack fusion is a moderate rather than a severe risk — less problematic than 85/40 but more so than the hard grades. Store on pallets, under cover, no more than two tiers high, away from open flame and heat sources, and keep the 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 standards and certification
Oxidized bitumen 85/25 from RAHA Gilsonite is manufactured and tested against the following frameworks.
| Standard | Covers |
|---|---|
| ASTM D312 | Standard specification for asphalt used in roofing |
| BS EN 13304:2009 | European framework for specification of oxidised bitumens |
| BS 3690 | British standard for bitumens for building and civil engineering |
| DIN 1995 | German standard for blown bitumen |
| ISIRI 118 | Iranian national standard |
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 on the certificate
Check where the softening point actually lands inside the 80 to 90 °C window. A batch at 81 °C gives you almost no margin in a warm market; one at 89 °C is nearly 95/25 territory. Because 85/25 is often specified right at the edge of its climate suitability, that difference decides whether the membrane holds. If your market runs warm, contract to a narrower band such as 86 to 90 °C rather than accepting the full range.
Frequently asked questions about oxidized bitumen 85/25
What does 85/25 mean in oxidized bitumen?
The first number is the ring-and-ball softening point in degrees Celsius, so approximately 85 °C. The second is the penetration at 25 °C in tenths of a millimetre, so approximately 25 dmm — a standard needle sinks 2.5 mm. The specification runs 80–90 °C for softening point and 20–30 dmm for penetration.
What is oxidized bitumen 85/25 used for?
Principally roofing membrane and felt manufacture, plus below-grade waterproofing, pipe coating, bituminous paints and primers, sound deadening and vibration damping compounds, electrical cable impregnation, construction adhesives and damp proof course sheet. It is the highest-volume oxidised grade worldwide.
Is 85/25 suitable for hot climates?
Not above about 42 °C ambient. A dark roof surface runs 30 to 35 °C above air temperature, so a 45 °C summer puts the membrane close to 80 °C, which sits inside the 80 to 90 °C softening band. The sheet softens and flows at the laps. For the Gulf, North Africa, South Asia and the equatorial belt, specify 95/25 or 105/35 instead.
What is the difference between 85/25 and 95/25?
They share the same penetration band of 20 to 30 dmm, so they behave similarly at ambient temperature. 95/25 carries roughly 10 °C more softening point. That margin matters where summer roof surfaces reach 75 to 82 °C — the point at which 85/25 becomes marginal. The price difference is small against the cost of a failed roof.
What is the difference between 85/25 and 85/40?
Same softening point band, but 85/40 carries roughly double the penetration — 35 to 45 dmm against 20 to 30. That decides cold behaviour. Below about 5 °C an 85/25 sheet becomes difficult to unroll and cracks at the fold; 85/40 stays workable. For Russia, the Baltics, Scandinavia and northern China, 85/40 is the correct grade.
What temperature do I melt oxidized bitumen 85/25 at?
Melt at 160 to 185 °C, pump at 170 to 190 °C and coat at 170 to 195 °C, using indirect heating. Do not exceed 215 °C. Prolonged hot holding continues the blowing reaction and hardens the grade, so melt per batch where the process allows.
Is oxidized bitumen 85/25 the same as blown asphalt 85/25?
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.
What is the shelf life of oxidized bitumen 85/25?
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 25 dmm the blocks are firm enough that stack fusion is a moderate rather than severe risk, though standard storage discipline still applies.
Which standards does 85/25 comply with?
ASTM D312 for asphalt used in roofing, BS EN 13304:2009 as the European framework for oxidised bitumens, BS 3690, DIN 1995 and ISIRI 118. Where a contract names a particular standard, the certificate of analysis will show the grade tested against that standard specifically.
Why does the solubility test use trichloroethylene rather than carbon disulphide?
Because carbon disulphide has been withdrawn from routine laboratory use on fire-safety grounds. The current method is ASTM D2042, which uses trichloroethylene. Older specifications sometimes still name CS₂, and a certificate quoting it is worth querying — it usually indicates the document was copied rather than generated from an actual test.
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.
Related grades and technical pages
Adjacent grades: oxidized bitumen 95/25 for warmer markets, 85/40 for cold-climate installation, 105/35 for hot climates, and 75/25 or 75/35 at the softer end. 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.
Why source oxidized bitumen 85/25 from RAHA Gilsonite?
- Direct production with offices in Dubai, Ankara and Isfahan
- Batch certificate of analysis before every shipment, with lot number and production date
- Full documentation — COA, MSDS, third-party inspection at loading
- Flexible shipment: FCL, LCL and bulk arrangements
- Honest grade advice, including when a different grade suits your climate better
- Certification against ASTM D312, BS EN 13304, BS 3690, DIN 1995 or your own specification
Send us the quantity, packing, discharge port and the peak summer temperature of the market your finished product will serve. That last figure decides whether 85/25 is right or whether 95/25 or 105/35 would prevent a warranty claim.
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
