Oxidized bitumen 75/25 carries the same 20 to 30 dmm penetration as 85/25, the world’s volume roofing grade, but sits roughly 10 °C lower on the softening scale. That makes it the cheapest medium-hardness blown grade available — and the one that should only be bought when the climate genuinely allows it. In cool markets and for below-grade work it is the sensible economy. On an exposed roof in anything warmer than northern Europe, it is a false saving.
RAHA Gilsonite supplies oxidized bitumen 75/25 against ASTM D312, BS EN 13304:2009 or a buyer’s own specification, with a batch certificate of analysis issued before loading. This page covers the specification, where the grade genuinely belongs, the low melting temperatures it needs, and an honest assessment of when spending slightly more on 85/25 is the better decision.
What is oxidized bitumen 75/25?
Oxidized bitumen, also called blown bitumen or blown asphalt, is produced by passing controlled hot air through penetration grade bitumen at elevated temperature. Oxygen reacts with the maltene fraction and converts it toward asphaltenes, raising the softening point and reducing the penetration.
Reading the designation
| Number | What it measures | Meaning |
|---|---|---|
| 75 | 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 75/25 is a standard-defined grade within that European framework.
Where 75/25 sits in the range
Two grades share the 70 to 80 °C softening band: 75/25 and 75/35. Together they are the lightest-blown products in the family. 75/25 is the firmer of the two, with 20 to 30 dmm penetration against 30 to 40.
That places it in a specific position: medium hardness, minimum heat resistance. It behaves at ambient temperature much like 85/25 or 95/25, but it softens roughly 10 and 20 °C earlier respectively.
The single question that decides this grade. What temperature will the material actually reach in service? If it is buried, shaded, indoors or in a genuinely cool climate, 75/25 does the job and costs less than anything above it. If it will sit on an exposed roof anywhere the summer air passes 30 °C, it will soften — and the saving disappears the first time a lap opens.
Oxidized bitumen 75/25 specification
| Property | Unit | Specification | Typical result | Test method |
|---|---|---|---|---|
| Softening point (ring & ball) | °C | 70–80 | 75 | ASTM D36 / EN 1427 |
| Penetration @25 °C, 100 g, 5 s | dmm | 20–30 | 25 | ASTM D5 / EN 1426 |
| Ductility @25 °C | cm | 3 min | 3–6 | ASTM D113 |
| Flash point (Cleveland open cup) | °C | 230 min | 255 | ASTM D92 |
| Solubility in trichloroethylene | wt % | 99 min | 99.5 | ASTM D2042 |
| Loss on heating | wt % | 0.5 max | 0.2 | ASTM D6 |
| Specific gravity @25 °C | — | 1.00–1.06 | 1.05 | 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 laboratory use on fire-safety grounds, and a certificate quoting it is worth querying. Test methods are maintained by ASTM International.
Applications of oxidized bitumen 75/25
The applications below share a characteristic: the material is protected from direct summer heat, either by being buried, shaded, indoors or in a cool climate.
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Below-grade waterproofing
Foundation tanking, basement protection and retaining wall coating. Ground temperature is stable and rarely exceeds 25 °C, so the low softening point is irrelevant.
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Damp proof course
DPC sheet manufacture and damp proof membrane, where the barrier sits within the wall structure rather than exposed.
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Waterproofing membrane, cool climates
Roofing felt and sheet for northern Europe, highland regions and similar markets where summer roof temperature stays well below 70 °C.
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Expansion joint filling
Pourable joint fillers and crack sealing compounds in concrete, particularly where the joint is at ground level or shaded.
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Pipe coating, buried line
Coating and wrapping compounds for pipe in stable ground temperature, where creep resistance matters more than heat margin.
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Electrical and industrial insulation
Insulation compounds and protective coatings for indoor installations and enclosures at moderate service temperature.
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Construction jointing and sealing
General bituminous fillers, packing compounds and site-mixed sealants across building work.
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Blending base
A common starting point for polymer-modified and filled compounds, where the modifier rather than the base provides heat resistance.
Where 75/25 is the wrong grade
Any exposed surface in a warm climate. A dark roof runs 30 to 35 °C above the air temperature, so a 40 °C summer puts the membrane at 70 to 75 °C — inside this grade’s softening band. The sheet softens, flows at the laps and can slide on a pitch. For the Mediterranean and warmer, specify 85/25 as a minimum, 95/25 for hot summers and 105/35 for the Gulf, North Africa and South Asia.
It also has limited creep resistance under sustained load compared with the hard grades. Static industrial mastics and pipe coating enamel on demanding installations belong to 90/10 or 105/15.
75/25 against 75/35 and 85/25
These three comparisons cover almost every real purchasing decision involving this grade.
| 75/25 | 75/35 | 85/25 | |
|---|---|---|---|
| Softening point | 70–80 °C | 70–80 °C | 80–90 °C |
| Penetration | 20–30 dmm | 30–40 dmm | 20–30 dmm |
| What differs | The baseline | Same heat limit, softer and more flowable | Same hardness, 10 °C more heat margin |
| Suits below-grade work | Yes — the economic choice | Yes, where flow helps | Yes, but you pay for margin you will not use |
| Suits exposed roofing | Cool climates only | Cool climates only | Yes up to about 42 °C ambient |
| Suits cable impregnation | Acceptable | Better — more flow | Marginal |
| Relative cost | Lowest | Similar | Modest premium |
| Melting temperature | 155–180 °C | 150–175 °C | 160–185 °C |
The honest position on the 85/25 comparison: the price difference between the two is small, and for any application where the material might see direct sun, that difference buys real protection. 75/25 earns its place on buried, shaded and indoor work, and in genuinely cool markets — not as a universal cheaper substitute.
How 75/25 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, sealing, pipe coating |
| 105/35 | 100–110 °C | 30–40 dmm | Medium | Membrane for hot climates |
| 105/15 | 100–110 °C | 10–20 dmm | Hard | Sealing, jointing, industrial mastics |
| 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 |
| 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, winter installation |
| 85/25 | 80–90 °C | 20–30 dmm | Medium | The volume roofing grade worldwide |
| 75/35 | 70–80 °C | 30–40 dmm | Softest | Cable impregnation, bituminous paint, damping |
| 75/25 | 70–80 °C | 20–30 dmm | Softest | Below-grade waterproofing, DPC, jointing, cool-climate membrane |
The full range is listed on our oxidized bitumen grades page.
Melting and application temperatures
| Operation | Temperature | Notes |
|---|---|---|
| Melting | 155–180 °C | Indirect heating. Among the lowest in the range — melts readily |
| Pumping | 165–185 °C | Heat traced lines. Sets in cold pipework |
| Application / blending | 170–195 °C | Jointing and sealing at the lower end; membrane coating higher |
| Absolute maximum | 210 °C | A low ceiling. Above this the penetration falls quickly |
| Hot holding | Avoid where possible | Continued heat continues the blowing reaction and hardens the grade |
A line configured for 85/25 will run this grade too hot. The difference is only about 5 °C at the melt stage but it compounds across a shift, and because the starting softening point is already low, the drift is proportionally larger. If you are switching grades, change the temperature settings first and check the penetration on the finished product afterwards.
Safety
The flash point is 230 °C minimum, which is the lowest of the blown grades and closest to the working range, so the margin is thinner than usual. Keep away from open flame and heat sources. 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 | Up to 25 MT palletised |
| Meltable bag | 25 kg | Goes into the melter with the material, no unwrapping | Up to 25 MT palletised |
| Carton box | 25 kg | Recommended for hot routes — rigid walls hold block shape | Up to 22 MT |
| Steel drum | 180 kg | New, sealed. Safest option for tropical transhipment | 80 drums ≈ 14.4 MT |
| Jumbo bag | 1,000 kg | For bulk orders where handling equipment exists | Up to 22 MT |
Customised packing is available on request.
Storage and shelf life — important for this grade
Two to three years in sealed packing kept dry, cool and out of direct sun. Chemical ageing is slow because the material is already blown.
The physical risk is high. With a softening point of only 70 to 80 °C, the margin between storage conditions and the softening range is among the narrowest in the family. A container crossing the Red Sea or the equator reaches 60 to 70 °C internally — at or inside that band. A pallet standing in tropical sun at a transhipment port can exceed it outright, and the result is block fusion or genuine deformation within the packing.
- Specify carton or drums for any route through the tropics.
- Limit stacking to two tiers, one tier in hot warehouses.
- Unload promptly on arrival rather than leaving containers standing.
- Store under cover, never in direct sun, in the coolest available space.
Our bitumen shelf life and storage guide covers the full picture including retest thresholds.
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. TDS and MSDS are supplied with every order.
What to check for this grade
Check where the softening point lands inside the 70 to 80 °C window. A batch at 71 °C has almost no margin for anything but buried or indoor work; one at 79 °C approaches 85/25 territory and gives useful headroom. Because this grade is usually chosen on cost and specified close to its limit, that difference decides whether it performs. If the application is borderline, contract to a narrower band such as 77 to 80 °C rather than accepting the full range.
Frequently asked questions about oxidized bitumen 75/25
What does 75/25 mean in oxidized bitumen?
The first number is the ring-and-ball softening point in degrees Celsius, so approximately 75 °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 70–80 °C for softening point and 20–30 dmm for penetration.
What is oxidized bitumen 75/25 used for?
Below-grade waterproofing, damp proof course sheet, waterproofing membrane for cool climates, expansion joint filling, pipe coating on buried line, electrical and industrial insulation compounds, construction jointing and sealing, and as a blending base for modified compounds. What these share is protection from direct summer heat.
What is the difference between 75/25 and 85/25?
They share the same penetration band of 20 to 30 dmm, so they behave similarly at ambient temperature. 85/25 carries roughly 10 °C more softening point. That margin decides whether the material survives on an exposed surface. 75/25 is the economic choice for buried, shaded and indoor work; 85/25 is the minimum for anything that sees direct sun.
What is the difference between 75/25 and 75/35?
They share the same softening point band of 70 to 80 °C. 75/25 carries 20 to 30 dmm penetration against 30 to 40 for 75/35, so 75/25 is firmer while 75/35 flows and wets better. For jointing, sealing and below-grade waterproofing where body helps, 75/25 works. For cable impregnation and thin-film paint where flow matters, 75/35 is the natural choice.
Can 75/25 be used for roofing membrane?
Only in genuinely cool climates. A dark roof runs 30 to 35 °C above air temperature, so a 40 °C summer puts the membrane at 70 to 75 °C, inside this grade’s softening band. The sheet softens and flows at the laps. For the Mediterranean and warmer, specify 85/25 as a minimum, 95/25 for hot summers and 105/35 for the Gulf and South Asia.
What temperature do I melt oxidized bitumen 75/25 at?
Melt at 155 to 180 °C, pump at 165 to 185 °C and apply at 170 to 195 °C, using indirect heating. Do not exceed 210 °C. A line configured for 85/25 will run this grade too hot, and because the starting softening point is already low, the drift is proportionally larger.
Is oxidized bitumen 75/25 the same as blown asphalt 75/25?
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.
Why does 75/25 need careful storage?
Because its softening point of 70 to 80 °C is among the lowest in the range and the margin to storage conditions is narrow. A container crossing the Red Sea or the equator reaches 60 to 70 °C internally, which is at or inside that band. Specify carton packing or drums on tropical routes, limit stacking, and unload promptly on arrival.
What is the shelf life of oxidized bitumen 75/25?
Two to three years in sealed packing kept dry, cool and out of direct sun. Chemical ageing is slow because the material is already blown. The practical limit is physical: with a low softening point, block fusion and deformation under heat are genuine risks on hot routes.
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 75/35 for more flow at the same heat limit, 85/25 where the material sees sun, 85/40 for cold-climate membrane, and 95/25 for warm markets. 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 75/25 from RAHA Gilsonite?
- Batch certificate of analysis before every shipment, with lot number and production date
- TDS and MSDS supplied with every order
- Third-party inspection accepted at loading by SGS, Bureau Veritas or your named surveyor
- Packing advice for tropical routes, where this grade is genuinely at risk
- Honest grade advice — if 75/25 is wrong for your application, we say so before you order
- Certification against ASTM D312, BS EN 13304 or your own specification
Send us the quantity, packing, discharge port and where the material will actually sit in service. If it is buried, shaded or in a cool climate, 75/25 is likely the economic answer. If it will see sun, we will tell you which grade to specify instead.
Dubai: No. 2305, Burlington Tower, Business Bay — +971 4 566 4998
Ankara: Karşıyaka District, 749 Street No. 30, Gölbaşı 06830 — +90 312 544 5481
