Bitumen 50/70: EN 12591 Specification, Applications and Export Supply

As with every penetration grade, the name is a measurement rather than a brand or a quality claim. The sample is brought to 25 °C, a standard needle under a 100 g load is released into it for five seconds, and the depth reached is read off in tenths of a millimetre. A result anywhere between 50 and 70 makes the material a 50/70. The procedure is EN 1426, which is technically equivalent to ASTM D5 and IS 1203, and the European convention writes the unit as ×0.1 mm where American practice writes dmm. Same number, same test, different house style.

What makes 50/70 worth a page of its own is not its position on the hardness scale but the standard sitting behind it. EN 12591 is the specification European road authorities write into their asphalt work, and it has been adopted well beyond the European Union — across the Balkans, in Turkey and its neighbours, in much of North Africa and the Levant, and through the Caucasus and Central Asia. Within that standard, 50/70 occupies the same central position that 60/70 occupies in the ASTM and Gulf export trade. It is the grade the specification writer reaches for by default, and the grade most national annexes name for general paving.

What EN 12591 controls that a Gulf data sheet does not

The difference between buying 50/70 and buying 60/70 is not really a difference in the binder. It is a difference in what the standard obliges the producer to prove. EN 12591 asks four things that an ASTM-based export data sheet typically does not:

• Ageing by RTFOT, not TFOT. Resistance to hardening is assessed by the rolling thin-film oven test to EN 12607-1, and three separate limits are placed on the residue — change of mass, retained penetration and softening point after ageing.
• A Fraass breaking point. EN 12593 measures the temperature at which a thin film of the binder cracks when it is cooled and flexed. It is absent from ASTM D946 entirely. Note how EN 12591 handles it: the Fraass limit belongs to the group of properties whose requirements are set according to national circumstances and climate, not to the group demanded of every grade in every country. That is exactly why it has to be named in the order — it is a hard requirement in the markets that call it up, and it is quietly left off a default certificate everywhere else.
• Solubility in toluene. EN 12592 uses toluene where ASTM D2042 uses trichloroethylene. The limit is the same 99.0 %, but the solvent is not, so a laboratory reporting solubility in TCE has not run the EN method.
• A flash point set by the standard. EN ISO 2592 (Cleveland open cup, now published as EN ISO 2592) with a minimum of 230 °C for this grade.

Everything above is checkable on a Certificate of Analysis. If a supplier offers 50/70 and the COA carries only penetration, softening point, ductility and TCE solubility, that COA is not evidence of EN 12591 conformity — it is an ASTM data sheet with a European grade name written at the top.

Where 50/70 sits in the EN ladder

Penetration and hardness run in opposite directions: a lower number means a stiffer binder. In EN 12591 terms, 50/70 sits one step below 40/60 and one step above 70/100, which means it is a general-purpose binder with enough stiffness for a Mediterranean summer and enough flexibility for a continental winter. The full ladder, with the penetration and softening point band for each grade, is set out further down this page.

Why the grade turns up in an export inquiry

Three situations account for most 50/70 enquiries. The first is a genuine EN-specification project, where the engineer has written EN 12591 50/70 into the contract and will check the COA against it. The second is a buyer in an ASTM-supplied region who has won work on a European-funded or European-designed scheme and now needs a binder certified to a standard their usual supplier does not test to. The third is a buyer who has been offered 60/70 as a substitute and wants to know whether it will be accepted. All three are answered below, and the third is answered honestly: sometimes yes, often no, and the reason usually comes down to two numbers.

Penetration and softening point, read as a pair

These two describe consistency and they travel together. For a straight-run 50/70 the ring and ball softening point normally lands between 46 and 54 °C, and for a given crude and process route the two properties track each other. A sample reporting, say, 55 ×0.1 mm penetration with a softening point well above 54 °C is not a superior 50/70 — it is out of grade, and it is a signal that the material may have been air-blown or blended rather than produced as a straight-run paving bitumen. Read the two numbers on the COA together, never separately. It costs nothing and it is the most useful authenticity check available to any penetration-grade buyer.

The upper softening point limit deserves particular attention because it is narrower than the Gulf convention. A 60/70 produced to a typical Middle East data sheet may legitimately report 55 or 56 °C, and that batch is simply outside the EN 50/70 band even though its penetration would pass. More on this in the comparison table below.

Fraass breaking point: the European line with no ASTM equivalent

The Fraass breaking point is measured to EN 12593. A thin film of binder is spread on a small flexible steel plaque, cooled at a controlled rate of one degree per minute, and flexed once every minute. The temperature at which the film first cracks is the Fraass breaking point, and for 50/70 the standard sets a maximum of -8 °C. Being a maximum, a more negative result is a better result.

The property exists because European road networks have to survive winters, and thermal cracking is the failure mode that follows a binder becoming brittle. It is worth being clear about what the test is and is not. It is an empirical brittleness index run on a thin film, not a fundamental rheological measurement, and it has a reputation for modest repeatability between laboratories. Low-temperature behaviour is measured far more precisely today by the bending beam rheometer that underpins performance grading, and a European engineer will usually know that. Two things follow for a buyer. First, EN 12591 does not impose Fraass on every purchase: it sits in the group of properties whose requirements are applied according to national circumstances and climate, so a country with mild winters may never call it up while a cold-winter road authority treats it as mandatory. Second, where it is called up it is the single line most often missing when an ASTM-based supplier offers material against a European specification, because no one runs it unless it was ordered. Check whether your project document actually invokes it, and if it does, name EN 12593 and the limit in the purchase order. It cannot be added to a certificate afterwards.

RTFOT is not TFOT

Both tests answer the same question — how much does this binder harden during hot mixing — and both run at 163 °C, which is why they are so often treated as interchangeable. They are not. The thin-film oven test (ASTM D1754) ages a static 3.2 mm layer of bitumen in a shallow dish on a rotating shelf. The rolling thin-film oven test (EN 12607-1, equivalent to ASTM D2872) ages a continuously renewed film inside rotating glass bottles with an air jet. The film geometry, the exposure and the results are different, and a European engineer is entitled to reject a TFOT result offered against an RTFOT requirement.

EN 12591 then places three limits on the aged residue rather than one. Change of mass is capped at ± 0.5 % — note the plus-or-minus, because a binder can gain mass through oxidation as well as lose it through volatilisation. Retained penetration must be at least 50 % of the original value, so a cargo entering the test at 60 ×0.1 mm must still measure at least 30 afterwards. And the softening point after ageing must be at least 48 °C, which puts a floor under the aged binder’s high-temperature stiffness. Taken together these three are the best predictor on the sheet of how the pavement will behave after the mixer, and they are the lines most often absent from a weak COA. The procedures behind each of them are set out in the bitumen test methods reference.

Solubility: same limit, different solvent

Solubility confirms the material is genuine bitumen and has not been extended with mineral filler or a foreign residue. EN 12592 sets a minimum of 99.0 %, identical to the ASTM D2042 limit, but determines it in toluene rather than trichloroethylene. In practice a genuine paving bitumen passes both. The point is documentary: if your contract says EN 12592 and the COA says trichloroethylene, the laboratory has run a different method and an inspecting engineer can say so.

Flash point: lower in the standard, higher on the data sheet

EN 12591 sets a minimum flash point of 230 °C for 50/70 by Cleveland open cup, against the 250 °C minimum that most Middle East export data sheets state for their paving grades. This is one of the few places where the commercial data sheet is stricter than the European standard, so it rarely causes a rejection. It does, however, change your handling margin. A binder certified at 230 °C is only forty degrees above a mixing temperature of 190 °C, and that is the number your terminal operator, your insurer and your safety case should be working from — not the number on a data sheet for a different grade.

What EN 12591 leaves out

Three lines that a Gulf certificate always carries are simply not in EN 12591: ductility, water content and density. That is a drafting decision, not a gap in the certificate. Ductility infers cohesion indirectly, from how far a briquette stretches before it snaps; the European committee chose to control the same concerns directly, through the softening point window and the three RTFOT limits, and left the stretching test out. Density is a slightly different case — absent from the requirement list but present on nearly every producer data sheet anyway, because converting invoiced tonnes into tank volume at the discharge terminal depends on it. If your own project document calls up ductility to ASTM D113 alongside the EN properties, ask for it in the purchase order. It is an inexpensive test, but nobody runs it by default on an EN order.

Write the EN test suite into the contract

The single most effective thing a buyer can do is name the methods, not just the grade. A purchase order that says “Bitumen 50/70” invites a data sheet built around ASTM methods with a European grade name at the top. A purchase order that says “Bitumen 50/70 to EN 12591, batch COA to report penetration EN 1426, softening point EN 1427, Fraass breaking point EN 12593, flash point EN ISO 2592, solubility EN 12592, and RTFOT residue to EN 12607-1 with retained penetration and softening point after ageing” leaves nothing to interpretation. Every line in that sentence is a line an engineer at destination will look for, and every one of them has to be arranged before production because none of them can be added retrospectively to a cargo that has already loaded.

CE marking and the Declaration of Performance

Inside the European Union and the EEA, EN 12591 does double duty. It is the technical specification, and it is also the harmonised standard sitting behind CE marking and the Declaration of Performance under the Construction Products framework. That paperwork is generated at the producing plant, through initial type testing and factory production control, and it travels with the product — a trading house cannot attach it to a cargo in transit, and it answers a different question from whether the binder meets the numbers in the table above. If your destination sits inside that area, establish before you commit tonnage who issues the Declaration of Performance for the material you are buying, and what obligations attach to the party whose name and address appear on the import. The harmonised standards list is revised periodically, so take the position from your importer, your customs broker or the relevant national authority rather than from a supplier’s assurance.

Outside that regulatory area the picture is much simpler. A great many markets buy to EN 12591 with no CE obligation whatsoever — the standard is being used purely as a technical specification because the national road authority adopted European practice. In those markets what the engineer wants is a Certificate of Analysis reported against the EN methods, and nothing more exotic than that.

The two documents that behave differently on an EN order

The commercial file is the same as for any bitumen shipment — invoice, packing list, bill of lading, Certificate of Origin from the chamber of commerce, Technical Data Sheet and Safety Data Sheet. Two items carry weight that is specific to an EN 12591 purchase, and both of them have to be settled before production rather than requested at the end.

• The Certificate of Analysis, with the EN method reference printed against each line. Right numbers under ASTM references do not demonstrate EN conformity, and an engineer working to a European specification is entitled to say so. Insist on measured, batch-specific figures: a certificate whose values land on the specification limit every time is a template, not a test report.
• The third-party inspection scope, written to include Fraass and RTFOT. A standard quality-and-quantity scope from SGS, Intertek, Bureau Veritas or an equivalent covers penetration, softening point and the quick lines. A Fraass determination and a full RTFOT with penetration and softening point on the residue are extra laboratory work measured in days, not hours. If they are not in the inspection order and in the production plan, they will not appear on the report — and this, rather than any failure of the binder, is the usual reason an otherwise sound EN cargo arrives with an incomplete certificate.

Where the destination is inside the EU or EEA, the Declaration of Performance discussed above belongs on the list as well.

Size the retained samples for the tests you might have to re-run

A result is only defensible if the sample behind it traces to the cargo, so have retained samples drawn and sealed in the inspector’s presence and held by both parties. Then size them for the standard you are actually buying to. Rechecking penetration and softening point consumes very little material; re-running an RTFOT and then testing penetration and softening point on the residue, plus a Fraass determination, consumes a great deal more. Agree the retained quantity in the contract, rather than discovering at dispute stage that the sealed tin will not stretch to the two tests the argument turns on. On drummed cargo, draw across the whole load instead of from whichever drum sits nearest the container door.

Packing, and what EN destinations tend to take

Packing sets container count, the handling plant needed at discharge, waste disposal and how quickly the cargo can be put to work, so it moves landed cost more than most buyers expect. The figures are governed by the packaging rather than the binder and are the same for any paving grade: roughly 12 MT as 80 new steel drums of 150 kg net in a 20-foot container, about 14.4 MT as 80 drums of 180 kg, around 20 MT in 1 MT jumbo or meltable poly bags, 20 to 25 MT in a bitutainer or tank container, and bulk parcels from about 1,000 MT upward.

What is worth saying about 50/70 in particular is that its destinations skew towards the heavy end of that list. Markets that specify EN 12591 usually have asphalt plants, heated storage and terminal capacity, so bulk and tank container carry a larger share of this grade than of the drummed export trade. That also makes the EN test suite easier to evidence, because a bulk parcel is sampled from the tank rather than from a scatter of drums. Where drums are used, write new into the contract — reconditioned drums are cheaper and are the single most common origin of contamination claims at discharge — and confirm that drum tare is excluded from the invoiced net weight. Exact counts vary with drum dimensions, container type and destination axle weight limits; the logistics and shipping page sets out the options.

• Bitumen 35/50 — the heavy-duty band for warm summers and channelised traffic
• Bitumen 30/45 — harder again, for high-modulus and very heavily loaded base layers