Bitumen 85/100: Specification, the 80/100 Difference and Export Supply

Read the designation backwards and it explains itself. 85 and 100 are the limits of a needle penetration result expressed in tenths of a millimetre (dmm), measured under fixed conditions — a 100 g load, 5 seconds, 25 °C — that are part of the measurement rather than footnotes to it. A penetration figure quoted without those three conditions is not a specification line, which is why the wording used in a purchase order matters as much as the numbers. The procedure is ASTM D5, with EN 1426 and IS 1203 as the European and Indian equivalents.

What separates 85/100 from most of the numbers a buyer meets on a bitumen offer is that it is a named grade in a specification. ASTM D946, the standard specification for penetration-graded asphalt cement, and its AASHTO counterpart M 20, define exactly five grades:

• 40-50 — hard binder, hot climates and heavily loaded pavements where rutting dominates.
• 60-70 — the mid-range workhorse and the highest-volume export grade.
• 85-100 — the soft-side paving grade covered by this page.
• 120-150 — soft, used for cool-climate paving and surface treatments.
• 200-300 — very soft, cold-climate and specialised applications.

Look at the gap in that list. ASTM D946 steps from 60-70 straight to 85-100 and leaves the 70 to 85 dmm range without a name. That gap is the historical reason the commercial band 80/100 came into existence, and it is why the two designations are confused so persistently and so expensively. The section below deals with it in full.

Where 85/100 sits on the hardness scale

Penetration and hardness run in opposite directions: a higher penetration number means a softer binder. At 85 to 100 dmm this grade is measurably softer than 60/70 and substantially softer than 40/50. In service that translates into three practical characteristics:

• Better low-temperature behaviour. A softer binder relaxes stress instead of storing it, so it resists thermal and fatigue cracking better through a cold season or a large daily temperature swing.
• Better workability. The mix stays compactable for longer and reaches target density at a lower rolling temperature, which matters on late-season paving, on thin lifts and on hand-laid work.
• Lower rut resistance. The same softness that helps in the cold is a liability under slow, heavy axle loads on a hot pavement. This is the reason 85/100 is not the default grade in the Gulf, and is the default in cooler and highland markets.

What ASTM D946 actually controls — and what it does not

D946 is a short specification. For grade 85-100 it sets a penetration band of 85 to 100 dmm, a minimum Cleveland open cup flash point of 232 °C, a minimum ductility at 25 °C of 100 cm, a minimum solubility in trichloroethylene of 99.0 %, and a minimum retained penetration after the thin-film oven test of 47 % of the original value.

It does not specify a softening point. Softening point appears on virtually every commercial technical data sheet because buyers, consultants and national road authorities ask for it, but a contract that says only ‘penetration grade 85-100 to ASTM D946’ has not contracted for a softening point at all. If the ring and ball value matters to your climate — and in a hot market it does — write the required range into the purchase order as a separate line rather than assuming the standard carries it for you.

Where each designation comes from

85/100 is a standard’s grade name. It is written into ASTM D946 and AASHTO M 20 as grade 85-100, with its own penetration band and its own ageing, flash point, ductility and solubility requirements. When a consultant writes ’85-100′ into a project specification, they are almost always invoking that standard and the whole requirement set that comes with it.

80/100 is a commercial band. No current ASTM or EN paving specification names an 80/100 grade. It grew up as a refinery production and trading convention, filling the 70 to 85 dmm gap that ASTM D946 leaves open, and it became the default heading on Middle East and South Asian export data sheets. Because the band is wider at the hard end, it is easier to produce to and easier to certify against — which is precisely why so many offers are written that way.

The arithmetic that decides every dispute

85–100 sits entirely inside 80–100. Two consequences follow, and both run in one direction only:

• Every batch that genuinely meets 85/100 also meets 80/100. Supplying 85/100 against an 80/100 requirement is always safe.
• A batch that meets 80/100 does not necessarily meet 85/100. A Certificate of Analysis reading 81, 83 or 84 dmm is fully on-specification against an 80/100 data sheet and out of specification against ASTM D946 grade 85-100.

That asymmetry is the entire problem. It is not a question of one grade being better made than the other; it is a question of which band the batch was certified against, and that is a decision taken long before the cargo reaches you.

How the dispute actually plays out

The sequence is almost always the same. A consultant writes ‘penetration grade 85-100 to ASTM D946’ into the project specification. The contractor buys against a competitively priced offer headed ‘Bitumen 80/100 (85/100)’, treating the two as synonyms because the offer presents them that way. The cargo loads, the batch Certificate of Analysis reads 83 dmm, and the resident engineer rejects the binder at the plant gate with the containers already inland and the paving window closing. Nobody lied at any point; two different documents were simply being compared to each other.

The commercial consequences fall on the buyer, not the seller, because the seller certified honestly against the band written on its own offer. Rejected binder has to be re-sold, re-shipped or re-blended, and none of those options is quick in a landlocked or capacity-constrained market.

How to write the inquiry so it cannot happen

• State the band and the method in the same sentence. ‘Penetration at 25 °C, 100 g, 5 s, ASTM D5: 85–100 dmm’ leaves nothing open to interpretation. A bare ’85/100′ in an email does not.
• Ask which band the Certificate of Analysis will be certified against. This is one question and it removes the entire risk. If the answer is 80/100, either change the offer or change your own specification — do not proceed on the assumption that the actual result will land above 85.
• Insist on actual measured values. A COA that reprints the specification range in the results column tells you nothing. You need the tested number, batch-referenced and dated.
• Agree a retest and umpire clause before shipment. ASTM D5 carries published repeatability and reproducibility limits, and two competent laboratories can legitimately differ on the same sample. A borderline single result should trigger a retest on the sealed retained sample at an agreed independent laboratory, not an automatic rejection.
• Decide in advance what happens between 80 and 85 dmm. Write the outcome into the contract — acceptance, price adjustment, retest, or rejection. Deciding it after the COA is issued means negotiating from the weaker position.

When 80/100 is genuinely the better thing to buy

If your own specification is silent on the classification standard and your engineer only needs a soft paving binder, the wider 80/100 band is usually the cheaper and faster purchase, because more of a refinery’s soft production qualifies. There is nothing inferior about it. The moment your specification names ASTM D946, AASHTO M 20, or a national standard that adopts either of them, buy 85/100 and accept whatever small premium the narrower band carries. The premium is always less than the cost of a rejected container load.

And where EN 12591 fits

European-derived specifications use neither number. EN 12591 names 70/100 and 100/150, and the 85 to 100 penetration band sits wholly inside 70/100 — which is exactly where the neat one-directional logic used above stops working, because EN 12591 does not classify on penetration alone. For 70/100 it also caps the ring and ball softening point at 51 °C, sets its own flash point minimum, and checks ageing with the rolling thin film oven test (EN 12607-1) rather than the TFOT that ASTM D946 uses. A fully compliant 85/100 certified at a 52 °C softening point therefore fails EN 12591 70/100 on a line that has nothing to do with penetration, and its ageing data is not even measured by the right method. Where a European specification applies, insist that the certification itself is issued against EN 12591 instead of reasoning across from the penetration band.

Softening point: the line that decides your climate

A typical 85/100 data sheet shows a ring and ball softening point of 45 to 52 °C, against roughly 49 to 56 °C for 60/70. Those few degrees are the practical difference between the two grades in service. In a market where a black surface reaches 55 to 60 °C on a summer afternoon, a binder softening at 46 °C under slow, heavily loaded axles will deform, and no amount of good mix design fully compensates. In a temperate, highland or continental market with real winters, the same softness is exactly what keeps the surface from cracking. Choose the grade for the pavement temperature range, not for the price difference.

Retained penetration: why the floor is 47 % and not 52 %

ASTM D946 requires grade 85-100 to retain at least 47 % of its original penetration after the thin-film oven test — ASTM D1754, five hours at 163 °C — measured by repeating ASTM D5 on the aged residue. The equivalent floor for grade 60-70 is 52 %. The softer grade is allowed to lose proportionally more because it starts from a much higher penetration and still lands somewhere workable.

Watch the absolute value, not only the percentage. A batch entering the test at 100 dmm and just passing the floor comes out near 47 dmm, which is still a functioning soft binder. A batch entering at 85 dmm and just passing the same floor comes out around 40 dmm — effectively 40/50 territory after nothing more than normal plant mixing. Two cargoes can both be compliant and behave very differently in the pavement. Ask for the actual pre-ageing and post-ageing penetration figures on the COA, not just the percentage.

Storage ages a soft grade toward a hard one

Every hour at temperature costs penetration. This matters more for 85/100 than for 60/70 because buyers of the softer grade are usually buying it for a specific low-temperature or workability reason, and that reason evaporates quietly in a hot storage tank. A cargo held at 175 °C for a week, or repeatedly reheated in drums, can arrive at the mixer measurably harder than the Certificate of Analysis says. Where the binder has spent an extended period in heated storage or in a hot transit, retest penetration on arrival before the mix design is finalised.

Ductility and solubility: the lines that catch a manufactured penetration

Penetration is the easiest property on the sheet to engineer, and a soft band is the easiest target to hit from below. A hard residue let down with a heavy oil stream or an extender will read somewhere in the 85 to 100 range on a needle test while behaving nothing like paving bitumen in a mix. ASTM D946 requires ductility at 25 °C, pulled at 5 cm/min, to reach 100 cm and solubility in trichloroethylene to reach 99.0 % for this grade, and a genuine straight-run 85/100 clears both with room to spare — so a ductility result sitting on the limit is a finding rather than a pass. Read those two lines together with loss on heating rather than each on its own: blended or extended material tends to fail the combination while the penetration figure alone still reads clean.

Flash point and safe handling

ASTM D946 sets a minimum Cleveland open cup flash point of 232 °C for grade 85-100. That figure governs storage and heating limits, appears on the Safety Data Sheet, and is what a terminal operator or insurer will ask for. It is a safety limit, not a working target — thermal damage to the binder starts far below it.

The document set to insist on

• Certificate of Analysis — batch-specific, carrying the measured penetration as a figure and stating in words which band the batch was certified against: ASTM D946 grade 85-100, or a commercial 80/100 data sheet. On this grade that one sentence settles the entire argument.
• Technical Data Sheet — check that its heading and its penetration line agree with each other. Sheets headed 80/100 with 85/100 written alongside are common, and they are where most of the confusion starts.
• Safety Data Sheet — carries the flash point and the heating limits your terminal, insurer and destination customs will ask about.
• Certificate of Origin — issued by the chamber of commerce, often needed for preferential duty treatment.
• Third-party inspection certificate — from an internationally recognised inspection agency, with the inspector instructed in writing to report penetration against the 85 to 100 band specifically rather than against the seller’s own range.
• Commercial invoice, packing list and bill of lading — the core commercial set.

On this grade the wording of the inspection instruction matters as much as the inspection. Ask for sealed retained samples drawn across the cargo rather than from the drums nearest the container door, and for penetration to be reported as a measured value rather than as a pass against a range: a cargo certified at 86 dmm and a cargo certified at 98 dmm are both grade 85-100, and after a mixing plant they will not be in the same place. If a result lands between 80 and 85, you want that sealed sample already in existence before anyone starts negotiating over it.