Bitumen Supply to Turkey: EN 12591 Grades, Regional Climate and the Overland Route

Iraq, Afghanistan, Pakistan, Turkmenistan and the wider Gulf all read an offer written as 60/70 without hesitation. Turkey does not use that designation, because Turkish paving bitumen is specified against EN 12591, Bitumen and bituminous binders — Specifications for paving grade bitumens, the European standard, adopted into the national catalogue by the Turkish Standards Institution and cited with a TS EN prefix. Adoption of a European Norm does not rewrite it; the requirement tables, the grade names and the test methods are the European ones. What that means in practice is that the grade an engineer names is an EN band — 50/70, 70/100, 35/50, 100/150 — and 60/70 is not one of them.

This is a bigger problem than a naming mismatch, because the two systems do not measure the same set of things. An EN certificate carries lines that an ASTM one has no procedure for, and it controls ageing by a different oven test. A supplier who submits a standard Middle East export Certificate of Analysis against a Turkish tender has not submitted a partially complete document; on the properties that matter most in the Turkish winter, the tests were never run.

Above the material standard

EN 12591 defines the binder. It is not, by itself, the document a Turkish contractor works to. State highway work is procured by the General Directorate of Highways (Karayollari Genel Mudurlugu, KGM), which publishes its own highway technical specification governing mix types, layers, binder content, laying and compaction, and which names the acceptable binder grade for each layer. Metropolitan municipalities, airport and industrial developers and private clients each procure against their own documents. Any of these can be tighter than the material standard, and a project may also invoke the EN mixture standards — the EN 13108 series for asphalt specifications and the EN 12697 series for mixture test methods. This page does not quote a specification document number for any of them. Take the operative requirement from the tender in front of you, and confirm which edition it incorporates.

The four things that decide a Turkish order

• The EN band. Named as an EN 12591 grade, and matched to the region the road is in rather than to national habit.
• The certificate. Reported to the EN test method series, including the low-temperature line and the EN 12607-1 ageing set. This is where most offers fail.
• The region. Turkey’s design climate changes by more within its own borders than most bitumen markets differ from each other. A binder that suits Antalya is the wrong choice for Ardahan.
• The mode. Where the cargo arrives overland across the eastern frontier, the commercial vocabulary is CPT or DAP to a named place, a consignment note rather than a bill of lading, and a truck rather than a container as the unit of quantity.

A note on spelling and on limits

Turkish place names are given here without diacritics so that they survive every character set a buyer might open this page in. More importantly: this page describes geography, specification practice and climate. It does not state that any particular crossing, port or rail service is currently open or available for bitumen, and it does not state transit times, freight rates, duty rates, licensing positions or vehicle capacities. Those are facts of the day, and they belong to your freight forwarder, your customs broker and your own legal and compliance advisers.

The EN 12591 paving range runs from the hardest band, 20/30, through 30/45, 35/50, 40/60, 50/70, 70/100, 100/150 and 160/220 to the softest, 250/330. The bands are wider at the soft end and narrower at the hard end, and they are not aligned with the ASTM bands. That is why 60/70 has no home in EN 12591: it sits across the 50/70 and 70/100 boundary, overlapping both and matching neither.

Why 50/70 and 70/100 are the mainstream pair

Two bands carry the great majority of European paving volume, and Turkey is no exception. 50/70 is the general-purpose warm-climate paving grade: stiff enough to resist rutting through a Mediterranean or Aegean summer, workable enough for ordinary hot-mix plant operation. 70/100 is its softer counterpart, chosen where the design risk moves from summer rutting to winter cracking — higher ground, colder provinces, and mixtures where flexibility is worth more than stiffness.

The remaining bands appear at the edges of the range. 35/50 is reached for where sustained heat and heavy, slow-moving traffic make rutting the dominant failure mode, and where the specification permits a harder binder. 100/150 appears in genuinely cold-region work. Harder grades still — 20/30 and 30/45, and the hard paving grades covered by EN 13924-1 — belong to high-modulus base course work rather than to ordinary surfacing.

Two-sided bands, and what that does to acceptance

An EN band is not a floor. 50/70 is accepted between 50 and 70 tenths of a millimetre and rejected at 72, and its softening point is controlled as a range rather than a minimum. A binder can be too soft or too hard for the same grade. This differs from the habit of reading a viscosity minimum or a single-sided requirement, and it makes the measured value on the batch certificate load-bearing rather than indicative.

Where the modified and non-paving products sit

Polymer modified binders are outside EN 12591. They are specified against EN 14023, the framework specification for polymer modified bitumens, which works on a class system rather than fixed values and adds elastic recovery to EN 13398 and storage stability to EN 13399. Cationic bituminous emulsions sit under EN 13808, and cutback and fluxed binders under EN 15322. A paving grade certificate evidences none of these. If a Turkish tender calls for a modified binder or an emulsion, an EN 12591 certificate is the wrong document, not merely an incomplete one.

The Fraass breaking point: a low-temperature line with no ASTM counterpart

The Fraass breaking point, measured to EN 12593, is the temperature at which a thin film of bitumen spread on a steel plaque first cracks when the plaque is repeatedly flexed while being cooled at a controlled rate. It is reported as a temperature in degrees Celsius, and the requirement is a maximum — the binder must break no warmer than the stated figure. It is the European system’s answer to the question that penetration and softening point cannot address: how cold can this binder get before it stops behaving as a flexible material and starts behaving as a brittle one.

There is no ASTM equivalent. ASTM approaches low-temperature behaviour through performance grading instead, using the bending beam rheometer, which is a different measurement producing a different number on different equipment. So a certificate produced against an ASTM paving schedule does not carry a Fraass value, cannot carry one, and the value cannot be inferred from penetration, softening point or anything else on the sheet. If the tender requires it, the test has to be commissioned specifically, on the batch, before the material is certified. Discovering the gap after dispatch is expensive; asking for it at the enquiry stage costs a line in an email.

This is not an academic requirement in Turkey. On the Mediterranean coast the Fraass line is met comfortably and nobody thinks about it. On the eastern plateau, where winter minima routinely fall below -20 °C, it is the line that decides whether the pavement survives a season.

EN 12607-1 RTFOT, not ASTM D1754 TFOT

Both systems simulate the ageing a binder undergoes during hot mixing, and they do it differently. ASTM D1754, the thin-film oven test, holds a static 3.2 mm film of binder in a shallow pan on a rotating shelf in a ventilated oven. EN 12607-1, the rolling thin-film oven test, continuously rolls a moving film around the inside of a rotating glass bottle with a jet of air directed into the mouth of each bottle as it passes, so fresh surface is exposed throughout the run. The exposures are not the same, the degree of ageing is not the same, and the results are not interchangeable. ASTM does have a rolling thin-film procedure of its own, ASTM D2872, which is the closer analogue — but it is not what a standard Middle East export certificate normally reports, because the export idiom controls ageing by loss on heating to D1754.

The ageing property ASTM does not control at all

Having aged the binder, EN 12591 measures three things on the residue: the change of mass, the retained penetration, and the increase in softening point. The first two have recognisable ASTM counterparts. The third does not appear in the ASTM paving specification at all. It is a direct cap on how much the binder is permitted to stiffen during mixing, and it catches a failure mode that retained penetration alone can miss. A certificate that reports loss on heating and retained penetration, but nothing about softening point on the aged residue, has left an EN requirement unevidenced.

The rest of the method series

Beyond those three, the EN series maps onto ASTM reasonably closely but never identically. Penetration to EN 1426 and softening point to EN 1427 are procedurally very close to ASTM D5 and D36. Flash point by Cleveland open cup is EN ISO 2592, which replaced the older EN ISO 2592 reference still seen on legacy documents. Solubility is EN 12592 — and here there is a genuine difference of substance, because the EN method determines solubility in toluene or xylene while ASTM D2042 uses trichloroethylene. The results answer the same question about adulteration, but a certificate should say which solvent was used rather than leaving it to be assumed. Density and relative density are EN 15326. And the sampling itself has its own standards: EN 58 for sampling bituminous binders and EN 12594 for preparing test samples. Disputes about a test result far more often turn on how the sample was drawn than on how it was tested, so sampling to the EN procedure, with sealed retained samples held by both parties, is worth writing into the contract.

The eastern land gate

The principal road frontier on Turkey’s eastern border is at Gurbulak in Agri province, in the shadow of Mount Ararat and a short distance from Dogubayazit, facing Bazargan across the frontier. It carries the main east-west artery across this frontier, approached through Marand and Maku, and continuing west as part of the European E80 route and the Asian Highway AH1 alignment. It is the longest-established of the road crossings on this frontier and, measured on a map, the shortest approach to eastern Turkey from a Middle East loading point. Whether it is open, and open to this commodity, on your dates is a question for a freight forwarder and not one this page answers.

It is not the only one. Esendere in Hakkari province faces Sero across the frontier, a more southerly and considerably more mountainous crossing. Further north, Kapikoy in Van province faces Razi, and this is where the historic railway alignment running east out of Istanbul reaches the border. Two physical facts about that alignment are worth knowing even if you never touch rail. The first is that the railway is 1435 mm standard gauge on both sides of this crossing, so unlike the 1520 mm broad-gauge corridors to the north this route carries no break of gauge at the frontier — a wagon does not have to be transhipped or have its bogies exchanged to continue. The second is that the alignment has never been physically continuous: it is interrupted by Lake Van, and the gap between Tatvan and Van is designed to be bridged by train ferry rather than by track. A corridor with a built-in break of mode in the middle behaves differently from a continuous one, and that is a planning fact rather than a curiosity. Whether the ferry link, or the line either side of it, is running and available for this commodity is a status question that this page does not answer.

None of this says a route is open, running, or available for bitumen. Border and corridor status changes for reasons that have nothing to do with the cargo, and it cannot be verified from a web page. Confirm the current position with your freight forwarder before you commit to a delivery date.

What the road west actually crosses

The distance from the eastern frontier to the industrial belt around the Sea of Marmara is on the order of 1,700 km, and it is not flat. The route runs across the Anatolian plateau through Agri, Erzurum and Erzincan, over ground that stays high for hundreds of kilometres and crosses passes that carry snow for a substantial part of the year. The Tahir pass east of Erzurum and the Kop pass between Bayburt and Erzurum both sit above 2,000 m; the Zigana pass on the descent to the Black Sea coast is comparable. This matters commercially in two ways. It means the eastern and southeastern provinces are the natural overland market, because they are close to the gate. And it means that a delivery to Istanbul or Izmir is a very long land haul that deserves an honest comparison against a sea option, rather than an automatic assumption in either direction.

The sea options, and where they make sense

Turkey has coastline on four seas and gateways on all of them. On the Mediterranean, Mersin, Iskenderun and Antalya serve the hot southern hinterland and the routes into central Anatolia. Around the Sea of Marmara, the Izmit and Kocaeli area, Ambarli, Gemlik and Derince sit at the centre of Turkish industry. On the Aegean, the Izmir and Aliaga area serves the western provinces. On the Black Sea, Samsun, Trabzon and Hopa serve the northern hinterland and form the coastal link toward Georgia.

The useful way to think about this is not sea against land, but which part of the country each mode reaches efficiently. The overland route through the eastern frontier reaches the east and southeast at short distance and the west at long distance. The sea routes reach the coasts directly and the interior by road. For a programme spread across the country, the sensible answer is often a split, and the comparison should be made on delivered cost to the named place rather than on freight rate alone.

Turkey as a transit country, not only a destination

Turkey sits between the Middle East, Europe and the Caucasus, and a great deal of cargo crosses it without stopping. Westward, the principal road gate to the European Union is Kapikule in Edirne province, facing Kapitan Andreevo in Bulgaria, and it is a long-established heavy-freight crossing. What the waiting position looks like there on any given date is a question for a forwarder, not a figure this page states. Ipsala, facing Kipoi, is the road gate to Greece. Northeastward, Sarp on the Black Sea coast is the coastal road gate to Georgia and the flattest route to the Caucasus, while Turkgozu at Posof in Ardahan province is the inland alternative toward Akhaltsikhe, higher and more exposed in winter. The Baku-Tbilisi-Kars railway alignment runs northeast from Kars through the frontier uplands toward Akhalkalaki in Georgia, where a transhipment and gauge-change facility exists for the simple reason that Turkey works on 1435 mm standard gauge and Georgia on 1520 mm broad gauge. And at Dilucu in Igdir province Turkey meets the Nakhchivan exclave of Azerbaijan at Sadarak. Southward, Habur at Silopi in Sirnak province faces Ibrahim Khalil and is the principal road gate to northern Iraq.

For a buyer this creates two different transactions that look similar and are not. A movement that ends in Turkey is an import, cleared at the frontier, with Turkish requirements applying to the goods. A movement that crosses Turkey is a customs transit, and the requirements that matter are those of the country where it finally clears. Getting these two confused is a documentation failure rather than a logistics one, and it is entirely avoidable by deciding at the contracting stage which one you are doing. Whether a particular transit is permissible, and what licensing or compliance obligations attach to it, is a question for your own legal and compliance advisers and your customs broker — not for a supplier page.