Bitumen 60/70: Specification, Applications and Export Supply

The name is not a brand or a quality claim — it is a measurement. A standard needle loaded with 100 g is allowed to penetrate a conditioned bitumen sample for 5 seconds at 25 °C, and the depth reached is recorded in tenths of a millimetre (dmm). If that depth lands between 60 and 70 dmm, the material is classified as 60/70. The test is defined in ASTM D5, and identically in EN 1426 and IS 1203.

Penetration grading was the original way of classifying paving binders and it remains the commercial language of the export market. Two other systems exist alongside it: viscosity grading (VG10 to VG40 under IS 73:2013, based on absolute viscosity at 60 °C) and performance grading (PG 58-22, PG 64-16 and similar, based on the pavement temperature range the binder is expected to survive). A single barrel of bitumen can be described in all three systems at once; they are different measuring sticks, not different products.

Where 60/70 sits in the hardness range

Penetration and hardness move in opposite directions. A lower penetration number means a harder binder:

• 30/40 and 40/50 — hard grades, used in very hot climates and heavily loaded pavements where rutting is the dominant risk.
• 60/70 — the mid-range grade. Enough stiffness for hot-climate paving, enough flexibility to resist cracking through a normal temperature cycle. This is why it dominates export volumes.
• 80/100 and 85/100 — softer grades, favoured in cooler climates and for surface treatments where workability matters more than rut resistance.
• 120/150 and 200/300 — soft grades, mostly cold-climate paving and specialised applications.

Why it is the default export grade

Three reasons keep 60/70 at the centre of the trade. First, it matches the climate of most of the markets that import bitumen — South Asia, Southeast Asia, the Middle East and much of Africa. Second, it is made from vacuum residue on ordinary production runs rather than as a special blend, so it is a routine product rather than a made-to-order one. Third, most national road specifications in those markets either name 60/70 directly or name an equivalent that 60/70 satisfies, which keeps it acceptable to the engineer signing off the project.

Penetration and softening point

These two travel together and describe consistency. A binder that arrives at 72 dmm is out of grade even if every other line passes — and it will behave differently in the mix. Softening point tells you the temperature at which the binder loses load-bearing stiffness; for a country with 45 °C summer pavement surface temperatures, a softening point at the bottom of the 49–56 °C band is a legitimate concern worth raising before shipment.

Ductility

Measured by stretching a briquette of bitumen at 5 cm/min at 25 °C until it breaks. A minimum of 100 cm indicates the binder has enough cohesion and elasticity to tolerate pavement movement without brittle fracture. Low ductility is a classic symptom of over-blown or heavily aged material.

Loss on heating and retained penetration

The thin-film oven test (ASTM D1754) simulates the ageing a binder undergoes during hot mixing. Two things are checked afterwards: how much mass was lost, and how much the penetration dropped. A maximum 20 % drop in penetration — the export data sheet wording, where ASTM D946 instead requires at least 52 % of the original penetration to be retained — means the binder is still workable and durable after plant mixing. This pair of tests is the single best predictor of premature pavement cracking, and it is the pair most often missing from a weak COA.

Solubility and spot test

Solubility in trichloroethylene at minimum 99.0 % confirms the material is genuine bitumen and not cut with mineral filler or extender. The spot test, reported negative, indicates the bitumen has not been over-cracked during processing. Together they are the anti-adulteration lines of the specification. If a supplier's COA omits solubility, treat that as a finding, not an oversight.

Flash point

The Cleveland open cup flash point at minimum 250 °C governs safe handling. It sets the hard ceiling for storage and heating temperature and it is what your insurer, your terminal and your tank farm operator will ask for. It also appears on the Safety Data Sheet that many destination customs authorities now request.

ASTM D946 and AASHTO M 20 name five penetration grades, and 60-70 is one of them. That is worth stating at the start of a section about confusion, because it changes where the confusion comes from. The problem is not that 60/70 is undefined — it is that four neighbouring bands, one of them undefined, two of them European and one Chinese, overlap it closely enough to pass a glance at the penetration line.

It is also worth being precise about what ASTM D946 actually requires of grade 60-70, because the export data sheet reproduced above is stricter than the standard in places and silent where the standard speaks. D946 requires penetration of 60 to 70 dmm, a Cleveland open cup flash point of at least 232 °C, ductility at 25 °C of at least 100 cm, solubility in trichloroethylene of at least 99.0 %, and a minimum of 52 % retained penetration on the thin-film oven test residue, together with a floor under the ductility of that residue that export certificates almost never carry. It sets no softening point requirement at all. The 49–56 °C band, the 250 °C flash point and the maximum 20 % drop in penetration on the table above are Middle East export data sheet practice, not requirements of D946 — and two of the three are materially tougher than the standard. That distinction settles arguments, so establish which document your contract names before you need it.

It is not the commercial 80/100 band

No current ASTM or EN paving specification contains a grade called 80/100. ASTM D946 steps from 60-70 straight to 85-100, and EN 12591 draws its soft band as 70/100, so the 80/100 designation grew up commercially on refinery data sheets in the Middle East, the Indian subcontinent and the CIS. One consequence is pure arithmetic and it catches people out regularly: between the top of 60/70 and the bottom of the commercial 80/100 band lies a ten-tenth gap, 70 to 80 dmm, that belongs to no ASTM grade and to no commercial band. A batch measuring 75 dmm is not a soft 60/70 and not a hard 80/100. It is out of grade against both, and the only paving specification that will take it on penetration is EN 12591 grade 70/100.

The second difference is the softening point. Regional data sheets put 60/70 at 49–56 °C and 80/100 at 45–52 °C, so the two bands share only three degrees. An offer of 60/70 or 80/100, whichever is available, is an offer of two binders that behave differently on the same road in the same summer. Where rutting is the risk being bought against, the softer band is not an alternative at any price, and the substitution is only ever defensible in one direction: toward the cooler climate, never toward the hotter one. The full treatment of that band is on the Bitumen 80/100 page.

It is not EN 50/70, and it is not EN 40/60

Both European grades get quoted as the counterpart of 60/70, and both mappings break — in opposite places.

EN 12591 grade 50/70 covers penetration 50–70 ×0.1 mm, so the entire 60/70 band sits inside it and penetration almost never blocks the substitution. What blocks it is the softening point ceiling. EN 12591 bands 50/70 at 46–54 °C, and a perfectly good export 60/70 reporting 55 or 56 °C is outside the European grade on a line its own data sheet says it passes. Three further differences follow. EN 12591 ages the binder on the rolling thin film oven test (EN 12607-1) and places three limits on the residue — mass change within ± 0.5 %, retained penetration at least 50 %, and softening point after ageing at least 48 °C — where the export certificate offers a static TFOT result (ASTM D1754) that a European engineer is entitled to refuse. EN 12592 determines solubility in toluene rather than trichloroethylene, so a TCE result is not an EN 12592 result even at the identical 99.0 % limit. And where the destination invokes it, EN 12591 adds a Fraass breaking point to EN 12593 that no ASTM-built certificate carries, because nobody runs a test that was never ordered. Those last two are the lines that arrive missing rather than failing, which is why they have to be settled before production. See the Bitumen 50/70 page for the full EN requirement set.

EN 12591 grade 40/60 is the mapping that looks wrong and is sometimes right. On penetration it barely overlaps 60/70 at all: 40–60 and 60–70 share exactly one value, 60 ×0.1 mm, so a batch at 65 dmm is squarely in grade as 60/70 and outside 40/60 entirely. On softening point the position reverses. EN 12591 bands 40/60 at 48–56 °C, sitting almost exactly on the 49–56 °C the export sheet quotes for 60/70, while the 50/70 band stops at 54 °C. So a hot-climate 60/70 running at the stiff end of its own data sheet resembles an EN 40/60 more than an EN 50/70 on the very line that decides the argument — and resembles neither on the line that decides the grade name. This is the general lesson about EN grades: adjacent bands overlap on penetration deliberately, and it is the softening point window and the ageing requirements that separate one grade from the next. Ordering by penetration alone is not ordering to EN 12591.

It is not the Chinese 70#

In the Chinese system the number is a nominal penetration and the band is written around it rather than by it. Under JTG F40-2004, 70# covers penetration at 25 °C of 60 to 80 tenths of a millimetre by JTG E20 method T 0604 — a window twice as wide as 60/70, with the whole of 60/70 sitting inside its lower half. The containment is real, and it runs in one direction only.

Read from the Chinese side, every batch that passes 60/70 on penetration also passes 70#. Read from the 60/70 side, containment fails across the entire top half of the Chinese band. A cargo at 74 dmm is comfortably mid-grade as 70#, is described on a genuine certificate as fully compliant, and is out of grade against a 60/70 purchase order by four tenths. Nothing in the paperwork announces this. The grade name is genuine, the certificate is genuine, and the number that fails is the one number everybody checks first and then stops checking.

The penetration line is also the easy part. 70# carries requirements ASTM D946 does not impose at those levels: flash point at a minimum of 260 °C by T 0611 against 232 °C in D946; solubility at a minimum of 99.5 % by T 0607 in all three quality classes, against 99.0 % in D946; ductility of 100 cm measured at 15 °C rather than at 25 °C, which is a different test and not a convertible one; a wax content ceiling by T 0615 with no Western counterpart at all; a penetration index window; and a retained penetration ratio after ageing. GB/T 15180 covers the same 60–80 consistency as AH-70 with a different limit set again. Traffic therefore flows automatically in neither direction: a 60/70 does not satisfy a 70# specification, and a 70# cargo does not satisfy a 60/70 contract unless its measured penetration happens to fall in the lower half of its own band. The Chinese requirement tables are set out on the Bitumen 70# and JTG F40 pages.

It is not VG-30, and it is not a PG grade

Both appear in the cross-reference table below, and the reason neither is a substitution takes one line each. VG-30 under IS 73:2013 is defined by absolute viscosity at 60 °C of 2400–3600 poise measured to IS 1206 (Part 2), with penetration only as a secondary requirement at a minimum of 45 dmm. A 60/70 usually lands inside that viscosity window; until somebody runs the viscosity, nobody knows whether this cargo does. A PG designation under AASHTO M320 or ASTM D6373 is not a band at all but the output of a test programme — rotational viscosity, dynamic shear rheometer before and after RTFOT, pressure ageing vessel and bending beam rheometer — and it cannot be inferred from penetration and softening point in either direction. A PG number quoted against a 60/70 certificate with no DSR result behind it is a label, not a grade.

And it is not a statement about process route

Finally, 60/70 says nothing about how the binder was made. A straight-run vacuum residue, a blend of a harder and a softer stream, and a straight-run base carrying a proportion of air-blown component can all be brought inside 60–70 dmm. Penetration is the cheapest property on a data sheet to hit, and a ten-tenth window is narrow enough that hitting it demonstrates process control rather than provenance. The lines that separate those three materials are solubility, the spot test, ductility and the ageing pair — plus the free arithmetic check set out further down this page, which compares penetration against softening point rather than either of them against a limit.

Where those temperatures come from

Mixing and compaction temperatures are not chosen for convenience. They are the temperatures at which the binder reaches a viscosity that lets the plant coat aggregate and lets a roller reorient it. The convention behind them, published by the Asphalt Institute and used in laboratory mix design rather than written into any binder specification, sets the mixing temperature where the binder viscosity is 0.17 ± 0.02 Pa·s and the compaction temperature where it is 0.28 ± 0.03 Pa·s, measured on a rotational viscometer to ASTM D4402 (AASHTO T 316). For a straight-run 60/70 those two viscosities fall inside the ranges given above, which is where those ranges come from. The practical point is that they are a property of the cargo in front of you rather than of the grade name: another 60/70 from another source can put them a few degrees either way, which is why a mix design developed against a previous cargo is not automatically valid for this one.

The window is a clock, not a temperature

Compaction has a top and a bottom. The top is the temperature at which the mix reaches the paver — commonly 135 to 150 °C in site practice, not a standard requirement. The bottom is the cessation temperature, the point below which rolling stops producing density and starts merely polishing the surface; for a conventional dense-graded mix with an unmodified binder, site practice puts it around 90 to 100 °C. The window is the time the mat takes to fall from one to the other, and that time is set by things nobody on the paving train controls: layer thickness above all, then base temperature, air temperature and wind speed.

Layer thickness dominates because the cooling is conduction-limited, and the time a mat takes to fall through a given temperature drop rises roughly with the square of its thickness. That is why a 30 mm wearing course and a 60 mm binder course are two different jobs even with identical mix out of the same silo: the thin lift can spend its entire window in a handful of minutes on a cold, windy morning, while the thick lift may hold it for the better part of an hour. Every decision about roller numbers, rolling pattern and how far the rollers may drop behind the paver is a decision about that clock, and it should be made from the layer thickness and the forecast rather than from habit.

What 60/70 specifically does to the clock

A 60/70 is stiffer than an 80/100 at every temperature the two share. At any given mat temperature it is further from the compaction viscosity than a softer grade would be, and two things follow. The rollers have to work closer behind the paver than they would on a soft grade. And the penalty for a stoppage — a late truck, a hand-work area, a longitudinal joint left standing — is larger, because a mat that has cooled is harder to bring back inside the window than a softer binder would have been. That same stiffness is exactly why 60/70 was specified in the first place: it resists deformation in service because it resists deformation under a roller. The grade does not give you both.

There is a second effect that belongs to the cargo rather than to the mix design. A binder that has already aged — in a hot tank, or through a drum heating cycle — is stiffer at every temperature than the same binder was on the day it was produced. Its compaction viscosity therefore arrives at a higher temperature, so the window closes earlier even though the delivery temperature on the docket is identical and every line on the certificate still passes. This is the on-site reason to care about the thin-film oven lines and about how long the cargo stood hot before loading. Ageing is not only a durability question that surfaces in five years. It is a density question that surfaces on the first day.

The wrong fix, and the ones that work

The instinctive answer to a closing window is to raise the mix temperature. It buys a few minutes and it costs binder life, because oxidative hardening accelerates with temperature: the binder that reaches the mat is then already older than the one that left the tank, and you have paid for a 60/70 and laid something harder than the mix design assumed. The 180 to 190 °C ceiling in the table above is a fuming and fire limit, not a quality limit. The quality limit is lower and it has no alarm attached to it.

The fixes that work are logistical rather than thermal. Match haul time and truck spacing to the layer thickness rather than to the plant's convenience. Get the breakdown roller into the hot end of the mat and treat the rolling pattern as a fixed sequence rather than an aspiration. Measure the mat temperature behind the screed and at breakdown rolling, and record it — a temperature record is the only evidence that will settle a density dispute later. Pave hot against hot at joints wherever the sequence permits, because a cold joint is a permanently under-compacted strip in the finished road. And stop rolling once the mat is below the cessation temperature: continuing adds no density, and on a thin lift it can fracture surface aggregate and bruise the mat.

Why the window earns this much attention

Because in-place air voids are the largest single lever on how long the pavement lasts, and the research position is consistent: permeability, durability and resistance to moisture damage all deteriorate sharply once in-place air voids rise much above about 8 %. The density requirement itself is a project specification figure, normally written as a minimum percentage of theoretical maximum density, so read it from your own documents rather than from any supplier's data sheet. What the binder specification contributes is the temperature at which that density is obtainable. Everything after that is programme. The wider mix-side treatment is on the asphalt mix design page.

The document set to insist on

• Certificate of Analysis (COA) — batch-specific, showing actual measured values, not the specification range copied across. A COA whose numbers exactly match the spec limits every time deserves scrutiny.
• Technical Data Sheet (TDS) — the general product specification and handling guidance.
• Safety Data Sheet (SDS/MSDS) — increasingly requested at destination customs and required by most terminals.
• Certificate of Origin — issued by the chamber of commerce; often required for duty treatment.
• Third-party inspection certificate — SGS, Intertek, Bureau Veritas or an equivalent, covering quality, quantity and packing condition at load port.
• Commercial invoice, packing list and bill of lading — the core commercial set.

Sampling matters as much as testing

Ask for retained samples to be sealed in the presence of the inspector and held by both parties. A test result is only defensible if the sample it came from can be traced to the cargo. For drummed shipments, sampling should be spread across the load rather than drawn from a single drum at the container door. The practices to name in the contract are ASTM D140, AASHTO T 40 or EN 58; the full procedure is set out on the sampling procedure page. This is also the point of appointing an independent inspector rather than accepting the seller's own sampling: it puts the drawing of the sample, the seals and the laboratory outside both parties, so a disagreement six weeks later is settled on a retained sample of the actual cargo instead of on whose laboratory is believed.

Reading a real 60/70 certificate, line by line

Checking whether the values fall inside the limits is the least informative thing that can be done with a Certificate of Analysis, because a fabricated certificate passes that test by construction. The useful reading asks a different question: does this document behave like a set of measurements? Three things answer it — the identity block, the pattern of the numbers, and the arithmetic that ties some lines to others.

Start with identity. A batch or lot number that also appears on the drums and the packing list. A production date. A sampling date with the practice named. Test dates separate from the issue date. An identified laboratory with an address, and a named signatory with a role. A certificate that cannot be tied to the drums in front of you evidences nothing about them, whatever its numbers say. The complete field list is on the Certificate of Analysis page.

Which lines scatter, and which sit on the limit for a legitimate reason

Real measurement is untidy. Every ASTM and EN method carries a precision and bias statement setting out how far two results on the same material are expected to differ, and the practical consequence is that genuine figures land in inconvenient places and move from batch to batch. Here is how the individual lines of a 60/70 certificate should look.

• Penetration is the line that ought to scatter most visibly. It is the average of several needle determinations on a conditioned sample, and real results land at 62, 64, 67. A figure that repeats identically shipment after shipment is a transcription. A figure of exactly 60 or exactly 70 is a limit.
• Softening point is read off a thermometer as a ball descends through a ring, and it lands on fractions of a degree. Exactly 49 °C — the bottom of the export band — recurring on consecutive certificates is the specification, not the material.
• Flash point does not sit near its limit on genuine material. A straight-run 60/70 normally flashes a long way above the 250 °C minimum, so a figure resting exactly on 250 °C is one of the more informative anomalies on the page: either it was copied from the limit column, or the binder is carrying light material it should not have.
• Solubility behaves the same way. Genuine paving bitumen dissolves almost completely and results cluster in the high nines, so a report of exactly 99.0 % — the floor — is a copied line far more often than it is a marginal batch. A missing solubility line is a finding in its own right, because it is the anti-adulteration test.
• Ductility is the exception, and it is worth knowing so that you do not chase it. A straight-run 60/70 usually out-pulls the trough, and a ductilometer has a finite length, so a report of 100 cm, 100+ cm or greater than 150 cm can be an entirely honest statement that the thread had not broken when the carriage ran out of travel. Read this line as a pass or a fail, not as a measurement.
• Loss on heating and water content are capped rather than banded, and genuine results normally sit well under the cap. Both printed at exactly 0.2 is the signature of a table filled in from the specification column.
• Specific gravity is reported to three decimals and lands somewhere inside 1.01–1.06. Exactly 1.01 or exactly 1.06 is a band edge, not a density.

The rule this adds up to is one sentence: a certificate on which every value sits exactly on a limit was copied from the specification table, and the tell is never one line but the pattern across all of them. Genuine results land in the middle of bands about as often as at the edges. The wider document-fraud treatment is on the fraud prevention page.

The two arithmetic checks you can run without a laboratory

Some lines are computed from others, and computed lines can be checked with nothing but a calculator.

The retained penetration check. The certificate should show the original penetration, the penetration of the thin-film oven test residue, and the percentage relationship between them, and the third should follow from the first two. If the percentage appears with no residue penetration behind it, that line was written rather than measured. This is also where two conventions collide, and they are not equally demanding. ASTM D946 requires a minimum of 52 % retained penetration for grade 60-70. The export data sheet convention instead caps the drop at 20 %, which is the same measurement inverted and means a minimum of 80 % retained — far stricter than the standard. Work an example on a cargo entering the oven at 66 dmm: to satisfy the export wording it must come out at 52.8 dmm or higher, and to satisfy ASTM D946 it need only come out at 34.3 dmm. Those are different pavements. Read your contract and establish which of the two it names, because a cargo can comply fully with ASTM D946 and still breach a contract written to the export line.

The penetration index check. Penetration and softening point are not independent numbers. For a given binder they are linked by its temperature susceptibility, and that relationship gives a free consistency test. Using the Pfeiffer and Van Doormaal relation, with penetration P in dmm and ring and ball softening point T in °C:

• A = (log 800 - log P) / (T - 25)
• PI = (20 - 500A) / (1 + 50A)

A 60/70 certificate reporting 65 dmm against 52 °C computes to a penetration index of about -0.06, and one reporting 68 dmm against 49 °C to about -0.7. Both are unremarkable, because straight-run paving bitumens normally compute to a penetration index between roughly -1 and +1. Now take the same 65 dmm reported against a softening point of 62 °C: that computes to about +2.1, a blown-grade signature on a paving-grade certificate. Either the material carries air-blown or blended component, or the two figures were invented separately by somebody who did not know they were related. Be clear about the status of this check: the penetration index is an engineering consistency indicator, not a requirement of ASTM D946 or of any export specification, and a value outside the usual range is a reason to ask a question rather than a basis for rejection. Its merit is that it costs nothing, takes a minute, and is impossible to anticipate if you are making numbers up.

Refinery-fresh, or through a hot storage cycle

Bitumen ages by oxidation and by loss of volatile components, and both accelerate with temperature and with exposed surface area. A cargo drummed straight off the production run and a cargo that has spent weeks in a hot tank — or been drummed, cooled, reheated and decanted — are not the same binder, even though both carry the same grade name and may carry the same batch certificate. The direction of the change is never in doubt: penetration falls, softening point rises, viscosity rises at every temperature, and ductility falls. What is in doubt is how far it has gone, and that is a measurement rather than an opinion.

Two consequences matter commercially. The first is margin. Specification limits do not move, so a cargo that left the plant at 68 dmm and has drifted to 61 dmm is still in grade and has already spent almost its entire penetration allowance before doing any work. The second is the mixing plant. The thin-film oven test exists to simulate the ageing a binder suffers during hot mixing; a binder that has already aged in storage enters that test with less to give, and can fail the retained penetration line even though the same material passed it at production.

The tests that show it, in the order they are worth asking for:

• A fresh penetration and softening point pair dated close to loading, by ASTM D5 and ASTM D36, compared against the values on the production certificate. This is the whole diagnosis and it is the cheapest test on the list. The comparison is the evidence; neither number means much alone.
• Loss on heating and retained penetration by ASTM D1754, with penetration by ASTM D5 on the residue — how much ageing margin is left for the plant to consume.
• The rolling thin film oven test, ASTM D2872, 163 °C for 85 minutes with continuous air flow, where the destination specification calls for RTFOT rather than the static TFOT. The two are not interchangeable and a result from one cannot be offered against a requirement for the other.
• Pressure ageing vessel, ASTM D6521, 20 hours at 2.10 MPa, which simulates years of in-service ageing rather than the mixing plant. It is a performance-grading test rather than a penetration-grade one, so order it only where the project is specified in PG terms.
• Viscosity ratio, where the destination works in viscosity grades: IS 73:2013 caps the ratio of absolute viscosity at 60 °C after RTFOT to the value before it at 4.0, which states ageing susceptibility as a limit directly.

Then ask the commercial questions that no test answers. What is the production date, as distinct from the certificate issue date? Is the cargo being drummed from production or out of storage, and at what temperature has it been held? Has any part of it been reheated, and how many times? Storage below 150 °C is the practical guidance in the table above precisely because prolonged higher temperature is what spends the binder. Drums standing at ambient temperature are not the risk — ageing effectively stops when the material is cold, which is why sealed drums keep for a long period and why the limiting factor there is drum corrosion rather than the binder. Every heating cycle is where the life actually goes. Storage practice is covered in more depth on the shelf life and storage page.