1
Rutting in hot weather
Softening point and viscosity at 60 °C. A binder at the soft end of its band in a 45 °C climate is the classic setup for wheel-track rutting. Push for the upper half of the softening point range.
Every bitumen specification, in every standard system, is assembled from the same four groups of properties. Once you see the structure, an unfamiliar specification stops being intimidating. The second half of this section deals with the four grading philosophies in commercial use, what each one actually measures, and why no arithmetic converts between them.
Penetration, softening point and viscosity. These define the grade name and determine whether the binder will rut in the heat or crack in the cold. This is the group the grade name comes from.
The thin film oven test or rolling thin film oven test, followed by retained penetration, viscosity ratio and ductility on the residue. This group predicts whether the pavement will still be intact in eight years. It is the group most often missing from a weak certificate, and it is the one that matters most for long-term performance.
Solubility in trichloroethylene, water content, ash content and the spot test. This is the anti-adulteration group. Extending bitumen with mineral filler or heavy residues is the most common quality fraud in the trade and these lines are what catch it.
Flash point and, for cutbacks, the distillation profile. This group governs storage temperature, insurance and terminal acceptance.
When you read any specification line, check three qualifiers before you compare numbers:
The four property groups above are universal. What is not universal is the property the grade name itself is built from. Four grading philosophies are in commercial use. They were designed in different decades to solve different problems, and each one measures something the others do not measure at all. A buyer who treats them as four dialects of one language will eventually accept a cargo that satisfies its own certificate and fails the acceptance test at destination.
ASTM D946 and AASHTO M20 in the export trade, EN 12591 in Europe. The entire grade name comes from a single measurement: a standard needle under a 100 g load is allowed to sink into a conditioned sample for exactly five seconds at 25 °C, and the depth in tenths of a millimetre is the result (ASTM D5, EN 1426, IS 1203). Grade 60/70 means that depth fell between 60 and 70 dmm. Everything else on the certificate — ductility, flash point, solubility, the thin film oven residue — is a qualifying requirement standing beside the grade rather than part of it, and softening point is not in ASTM D946 at all.
Know which names the standards actually contain. ASTM D946 and AASHTO M20 name five grades and no others: 40-50, 60-70, 85-100, 120-150 and 200-300. EN 12591 names its own series on different bands — 20/30, 30/45, 35/50, 40/60, 50/70, 70/100, 100/150, 160/220 and 250/330 — with nothing harder than 20/30 inside it and no 120/150 and no 200/300 anywhere in it. Grades harder than 20/30 — 15/25 and 10/20 — are specified separately in EN 13924-1 rather than in EN 12591. The familiar export designations 30/40 and 80/100 belong to neither document: they are refinery data sheet names, and an enquiry written as “ASTM 30/40” cannot be closed by any certificate because there is no limit table to test the cargo against.
The strengths are practical. The test is quick, cheap, needs no capital equipment and is available in every laboratory in every port, which is why penetration grading remains the commercial language of the bitumen export trade. The limitation is structural. 25 °C is not a temperature at which pavements fail; it is close to the mean annual temperature of a temperate country and close to nothing at all in a desert summer or a northern winter. Penetration is one point on a stiffness-versus-temperature curve and it says nothing about the slope of that curve. Two binders that both penetrate 65 dmm can differ substantially in viscosity at 60 °C and in stiffness at −10 °C, because temperature susceptibility varies with crude source and processing route. Ageing is not in the grade either: it has to be read from the residue block as a separate exercise.
IS 73:2013 in India, ASTM D3381 in the older American system. The grade is set by absolute viscosity at 60 °C in poise, measured in a vacuum capillary viscometer (ASTM D2171, IS 1206 Part 2). The choice of 60 °C is the whole point of the system: it approximates the temperature a pavement surface layer actually reaches in a hot climate, so the grading number is a statement about behaviour in the condition where rutting happens rather than in a bath chosen for convenience. A second measurement, kinematic viscosity at 135 °C (ASTM D2170, IS 1206 Part 3), covers the temperature at which the binder is pumped, sprayed and mixed with aggregate.
The designation is close to arithmetic. VG-30 requires 2400–3600 poise at 60 °C, so the number is approximately the mid-band expressed in hundreds of poise; VG-10 is 800–1200, VG-20 is 1600–2400 and VG-40 is 3200–4800. Note what the system does with penetration: IS 73:2013 sets only a minimum penetration for each grade — 45 dmm for VG-30 — and no maximum at all. A VG-30 is therefore not “a 60/70”, and two fully compliant VG-30 cargoes can sit a long way apart on the needle.
ASTM D3381 is worth knowing about because it introduced the idea the performance system was later built on. It carries two separate requirement tables: AC grades, viscosity-graded at 60 °C on the binder as delivered, and AR grades, viscosity-graded at 60 °C on the residue recovered from the rolling thin film oven test. AR grading was the first widely used specification to grade the material as it will be after the mixing plant rather than as it arrives in the tank. What viscosity grading still does not address is the cold end: nothing in a 60 °C viscosity figure predicts transverse cracking at −15 °C, which is why IS 73:2013 retains a minimum penetration and a residue ductility line to stand in for it.
AASHTO M320 and ASTM D6373. This is the one system whose logic runs the other way round. In penetration and viscosity grading the test temperature is fixed and the pass limit moves with the grade. In performance grading the limit is fixed and the temperature moves with the grade. PG 64-22 means the binder still meets a rutting criterion at a 64 °C pavement design temperature and still meets a cracking criterion at a −22 °C pavement design temperature. Both figures are pavement temperatures derived from climate data, not air temperatures and not bath temperatures picked for laboratory convenience.
The second structural difference is the material tested. A performance grade is demonstrated on three states of the same binder, produced in sequence from one charge: the original binder; the residue from the rolling thin film oven test (ASTM D2872), which stands for the hot mixing plant; and the residue from the pressure ageing vessel (ASTM D6521, twenty hours at 2.10 MPa), which stands for years of in-service oxidation. Rotational viscosity at 135 °C (ASTM D4402) is capped at 3.0 Pa·s so that the binder can be pumped at all. The dynamic shear rheometer (ASTM D7175) supplies G*/sin δ of at least 1.00 kPa on original binder and 2.20 kPa on RTFOT residue at the high grade temperature, and G*·sin δ of no more than 5000 kPa on PAV residue at the intermediate temperature. The bending beam rheometer (ASTM D6648) supplies creep stiffness of no more than 300 MPa and an m-value of at least 0.300 on PAV residue. Durability is not bolted on in this system; it is inside the grade.
AASHTO M332 extends the same framework by measuring traffic instead of assuming it, using the multiple stress creep recovery test (AASHTO T350, ASTM D7405) on RTFOT residue and adding a letter to the designation: PG 64S-22, 64H-22, 64V-22 and 64E-22, with non-recoverable creep compliance at 3.2 kPa capped at 4.5, 2.0, 1.0 and 0.5 kPa−1 respectively. The price of the whole system is instrumentation. A dynamic shear rheometer, a pressure ageing vessel and a bending beam rheometer are capital that a penetration bath is not, which is why performance grading dominates where it was developed and appears patchily elsewhere.
JTG F40-2004 for highway construction and GB/T 15180 for heavy-traffic road petroleum asphalt. This system starts where penetration grading starts and then adds a second dimension at right angles to it.
The grade number follows the nominal-penetration convention rather than the band convention. Grade 70# is penetration 60–80 dmm, with the name sitting at the centre of the band instead of at its edge, and the series runs 30#, 50#, 70#, 90#, 110#, 130# and 160#. Reading 70# as 60–70 is the single most common misreading in China-facing trade, and it is a misreading that survives all the way to the acceptance laboratory.
The second dimension is the quality class: A, B and C. The class is not a marketing tier. It is a permission attached to particular pavement layers. Class A is accepted for all grades and all layers on every class of highway; class B for the lower layers of expressways and class-1 highways, and for all layers of highways of lower class; class C for class-2 highways and below. What separates the classes is a set of properties an ASTM-based certificate usually does not carry at all: wax content by the distillation method, capped at 2.2 % for class A, 3.0 % for class B and 4.5 % for class C; softening point, which at 70# steps down 46, 45 and 43 °C across the three classes; a penetration index window of −1.5 to +1.0 at 70# class A, the window this page can source, with the class B and class C windows left to the requirement table itself rather than assumed to be the same; and a ladder of ageing residue requirements that tightens from C to A.
Around both of those sits the climate zone code, a three-part figure such as 1-4-1 or 2-2-2 describing summer high temperature, winter low temperature and annual rainfall. It never appears in the grade name. It steers which grade is appropriate and it moves the low-temperature ductility and residue limits that the chosen grade then has to meet. A Chinese requirement is therefore three pieces of information rather than one: grade, class and zone. An enquiry that supplies only the grade cannot be answered with a technically checkable offer. The JTG F40 page sets out the requirement table, and the climate zone page sets out how the code is read.
Several individual limits are also simply higher than their ASTM counterparts, and that is where otherwise compliant export cargo gets refused. Solubility is minimum 99.5 % at 70# and 90# class A against 99.0 % in ASTM D946. Flash point is minimum 260 °C at 70#, 50# and 30# against the ASTM D946 floor of 232 °C. Ductility is required at 15 °C and again at 10 °C rather than at 25 °C, and 100 cm at 25 °C is no evidence at all of 100 cm at 15 °C. GB/T 15180 adds a trap of its own: it sets a two-sided softening point window for AH-70 of 44–54 °C where JTG F40 sets a floor only, so a cargo testing at 55 °C passes one Chinese standard and fails the other.
There is no formula, no factor and no lookup table that turns a grade in one system into a grade in another. This is not a gap in the literature that somebody will eventually fill. It follows from what the systems are.
The operative rule is short. A cargo is shown to meet a specification only by being tested against that specification’s own properties, methods and temperatures. If the contract names IS 73:2013 VG-30, the acceptance evidence is absolute viscosity at 60 °C by IS 1206 Part 2; a certificate showing penetration 60–70 does not demonstrate compliance even where the material would in fact have passed. If it names AASHTO M320 PG 64-22, the evidence is rotational viscosity, dynamic shear and bending beam data at the temperatures the grade name dictates; a penetration figure does not become a performance grade by sitting next to one on a data sheet. Nearest-neighbour tables have one legitimate use, which is to shortlist what to ask for and then test — the grade equivalence page sets out those approximate neighbours and, more usefully, the mappings that do not exist at all.
The same cargo can be described by all four systems and will need four different test reports to prove it. Read down a column to understand one system; read across a row to see why a number from one column cannot be moved into another.
| Question | Penetration grading | Viscosity grading | Performance grading | Chinese grade and class |
|---|---|---|---|---|
| Governing standard | ASTM D946 and AASHTO M20, which name five grades only — 40-50, 60-70, 85-100, 120-150 and 200-300; EN 12591 in Europe, on its own nine bands from 20/30 to 250/330, with harder grades in EN 13924-1 | IS 73:2013 in India; ASTM D3381 in the older American system | AASHTO M320 and ASTM D6373; AASHTO M332 where traffic is measured | JTG F40-2004 for highway construction; GB/T 15180 for heavy-traffic road asphalt |
| What the grade name is built from | Depth a 100 g needle sinks in 5 s at 25 °C (ASTM D5) | Absolute viscosity at 60 °C in poise (ASTM D2171, IS 1206 Part 2) | The pavement design temperatures at which fixed rheological criteria are still met | A nominal penetration band at 25 °C, with a separate quality class letter beside it |
| What the name actually means | 60/70 means penetration fell between 60 and 70 dmm; the two numbers are the limits themselves | VG-30 means 2400–3600 poise at 60 °C; the number is roughly the mid-band in hundreds of poise | PG 64-22 means it passes at a 64 °C high pavement temperature and a −22 °C low pavement temperature | 70# means penetration 60–80 dmm; the number is the nominal centre of the band, not a limit |
| Test temperatures involved | One: 25 °C | Two: 60 °C sets the grade, 135 °C covers handling | The whole service range. The limit is fixed and the temperature moves with the grade | 25 °C sets the grade; class and zone add requirements at 15 °C, 10 °C and 60 °C |
| Condition of the material tested | Binder as delivered; ageing handled by separate TFOT or RTFOT residue lines | As delivered for IS 73 VG grades and ASTM AC grades; RTFOT residue for ASTM AR grades | Original binder, RTFOT residue and PAV residue in sequence — ageing sits inside the grade | As delivered, with RTFOT or TFOT residue limits that tighten by quality class and climate zone |
| How the cold end is handled | Not by the grade. ASTM D946 sets no cold-end requirement at all; EN 12591 requires a Fraass breaking point by EN 12593, which no ASTM penetration grade measures | Not by the grade. A minimum penetration and a residue ductility line stand in for it | Directly, by BBR creep stiffness of no more than 300 MPa and an m-value of at least 0.300 at L + 10 °C | By ductility at 10 °C and by residue ductility, with the limits selected by the climate zone code |
| Equipment the acceptance laboratory needs | Penetrometer and a controlled water bath | Vacuum capillary and kinematic viscometers with timed baths | Rotational viscometer, DSR, RTFOT oven, pressure ageing vessel and BBR | Penetration and ring-and-ball apparatus, plus wax distillation and 60 °C dynamic viscosity capability |
| What it controls well | Consistency at handling temperature, comparability between competing offers, and fast verification at any port | Rutting resistance in a hot climate, and pumpability and coating at the plant | Rutting, fatigue and thermal cracking, each against its own criterion, on material aged to two stages | Wax-driven failures, low-temperature cracking, and matching the binder to the road class and the layer |
| What it leaves unanswered | Behaviour at any temperature other than 25 °C, and the slope of the stiffness curve either side of it | Everything at the cold end of the service range | Compatibility with the local aggregate; and it requires a laboratory most discharge ports do not have | Nothing transfers outside China, because the quality class has no counterpart in ASTM or EN |
| What a compliant certificate must show | Penetration, ductility, flash point, solubility and the full TFOT residue block under ASTM D946; softening point as well on any export data sheet, and as a two-sided band under EN 12591, which D946 does not require | Absolute viscosity at 60 °C, kinematic viscosity at 135 °C, minimum penetration, and the RTFOT viscosity ratio and residue ductility | Rotational viscosity, DSR on original and RTFOT residue, DSR on PAV residue, BBR stiffness and m-value, each at the temperature the grade dictates | Penetration, softening point, ductility at 15 and 10 °C, wax content, penetration index, 60 °C dynamic viscosity and the residue block |
The typical export specification quoted on Middle East refinery technical data sheets, not the text of any standard. Two of the four column headings are trade designations rather than standard grades: ASTM D946 and AASHTO M20 name 40-50, 60-70, 85-100, 120-150 and 200-300 and nothing else, so there is no ASTM 30/40 and no ASTM 80/100 to test a cargo against, and the European bands under EN 12591 are different again — the nearest defined neighbour of 30/40 is EN 12591 30/45, which is a different band with a softening point window on top of it. Read the note below the table before quoting any line of it into a contract.
| Property | Test method | Unit | 30/40 | 40/50 | 60/70 | 80/100 |
|---|---|---|---|---|---|---|
| Penetration at 25 °C | ASTM D5 | dmm | 30–40 | 40–50 | 60–70 | 80–100 |
| Softening point, R&B | ASTM D36 | °C | 55–63 | 52–60 | 49–56 | 45–52 |
| Ductility at 25 °C, min | ASTM D113 | cm | 100 | 100 | 100 | 100 |
| Flash point, COC, min | ASTM D92 | °C | 250 | 250 | 250 | 232 |
| Solubility in TCE, min | ASTM D2042 | wt % | 99.0 | 99.0 | 99.0 | 99.0 |
| Specific gravity at 25 °C | ASTM D70 | — | 1.01–1.06 | 1.01–1.06 | 1.01–1.06 | 1.01–1.05 |
| Loss on heating, max | ASTM D1754 | wt % | 0.2 | 0.2 | 0.2 | 0.5 |
| Drop in penetration, max | ASTM D5 on residue | % | 20 | 20 | 20 | 20 |
| Spot test | AASHTO T102 | — | Negative | Negative | Negative | Negative |
The Indian standard, published by the Bureau of Indian Standards and named in Indian highway and public-works procurement. Unlike the tables above, every figure here is a requirement of the standard itself. Note that ageing is assessed by RTFOT, not TFOT, and that the penetration line is a floor with no ceiling above it.
| Property | Test method | Unit | VG-10 | VG-20 | VG-30 | VG-40 |
|---|---|---|---|---|---|---|
| Absolute viscosity at 60 °C | IS 1206 Part 2 / ASTM D2171 | poise | 800–1200 | 1600–2400 | 2400–3600 | 3200–4800 |
| Kinematic viscosity at 135 °C, min | IS 1206 Part 3 / ASTM D2170 | cSt | 250 | 300 | 350 | 400 |
| Penetration at 25 °C, min | IS 1203 / ASTM D5 | dmm | 80 | 60 | 45 | 35 |
| Softening point, min | IS 1205 / ASTM D36 | °C | 40 | 45 | 47 | 50 |
| Flash point, COC, min | IS 1448 P:69 / ASTM D92 | °C | 220 | 220 | 220 | 220 |
| Solubility in TCE, min | IS 1216 / ASTM D2042 | wt % | 99.0 | 99.0 | 99.0 | 99.0 |
| Viscosity ratio at 60 °C after RTFOT, max | IS 9382 / ASTM D2872 | — | 4.0 | 4.0 | 4.0 | 4.0 |
| Ductility at 25 °C after RTFOT, min | IS 1208 / ASTM D113 | cm | 75 | 50 | 40 | 25 |
| Specific gravity at 27 °C, min | IS 1202 / ASTM D70 | — | 0.99 | 0.99 | 0.99 | 0.99 |
Named by softening point over penetration — the reverse of the penetration-grade convention, and the single most common source of confusion in industrial bitumen enquiries.
| Grade | Softening point (ASTM D36) | Penetration at 25 °C (ASTM D5) | Primary application |
|---|---|---|---|
| 75/25 | 70–80 °C | 20–30 dmm | General waterproofing, lower-temperature service |
| 85/25 | 80–90 °C | 20–30 dmm | Roofing felt and membranes — the volume grade |
| 90/15 | 85–95 °C | 10–20 dmm | Pipe coating, insulating and sound-deadening compounds |
| 95/25 | 90–100 °C | 20–30 dmm | Hot-climate roofing, vertical upstands and slopes |
| 105/35 | 100–110 °C | 30–40 dmm | Specialised adhesives and industrial compounds |
| 115/15 | 110–120 °C | 10–20 dmm | Joint filling, high-temperature service, insulation |
The grade number is the lower bound of the kinematic viscosity range at 60 °C. Flash point rises with grade number because heavier grades hold less solvent.
| Grade | Kinematic viscosity at 60 °C (cSt) | Flash point, Tag open cup, min | Typical use |
|---|---|---|---|
| MC-30 | 30–60 | 38 °C | Prime coat on tight or fine-grained granular bases |
| MC-70 | 70–140 | 38 °C | Prime coat on coarser or more porous bases; cold patch |
| MC-250 | 250–500 | 66 °C | Surface dressing, patch mixing, stockpile cold mix |
| MC-800 | 800–1600 | 66 °C | Surface dressing and premix needing higher residual binder |
| MC-3000 | 3000–6000 | 79 °C | Premix and heavy-duty patching |
Emulsions are classified by electrical charge and by how quickly they break. The letters carry the whole specification logic.
| Grade | Charge | Setting speed | Typical application | Normally diluted |
|---|---|---|---|---|
| CRS-1 | Cationic | Rapid | Surface dressing, chip seal | No |
| CRS-2 | Cationic | Rapid | Chip seal with larger aggregate | No |
| CMS-2 | Cationic | Medium | Cold mix, patching mixtures | No |
| CMS-2h | Cationic | Medium | Cold mix requiring a harder residue | No |
| CSS-1 | Cationic | Slow | Tack coat, prime coat, slurry seal | Yes, commonly 1:1 |
| CSS-1h | Cationic | Slow | Slurry seal and micro-surfacing | Yes |
| RS-1 / RS-2 | Anionic | Rapid | Surface dressing on suitable aggregate | No |
| SS-1 / SS-1h | Anionic | Slow | Tack coat, slurry seal | Yes |
These are the lines that appear on almost every bitumen certificate regardless of which system the grade came from. Each one exists because a specific pavement or handling failure was traced back to it. The fourth column is the reason the line is on the page: it is what a result outside the limit is predicting about the material once it leaves the tank. Where a figure below carries a standard designation it is a requirement of that standard for the grade named; where it is described as export practice it is what commonly appears on Middle East refinery data sheets and is not a requirement of any standard.
| Property | Test method and condition | What the test physically measures | What a failure of this line predicts in service |
|---|---|---|---|
| Penetration at 25 °C | ASTM D5, EN 1426 or IS 1203. Needle under a 100 g load for 5 s at 25 °C, result in dmm | Depth of penetration — an empirical index of consistency at mean service temperature. It defines the grade in three of the four grading systems | Above the band: tenderness under the roller, shoving at intersections and bleeding in hot weather. Below the band: poor aggregate coating, a mix that will not compact at the target temperature, and transverse cracking in the first cold season |
| Softening point, ring and ball | ASTM D36, EN 1427 or IS 1205. 3.5 g steel ball, bath heated at 5 °C per minute | The temperature at which the specimen has softened enough to sag a set distance under the ball. It is conventionally treated as an equi-viscous temperature rather than a melting point, because bitumen has no melting point | Low against the service climate: rutting, flushing, binder drain-down in gap-graded and porous mixes, and drums slumping or welding together in a hot yard. Unusually high against the reported penetration: blown or blended component rather than straight-run material |
| Ductility at 25 °C | ASTM D113 or IS 1208. Briquette pulled at 5 cm per minute in a 25 °C bath | Elongation in cm before the thread breaks — a proxy for cohesion and for the presence of over-aged, cracked or blended material | Ravelling, loss of cohesion in the mix and poor crack-sealing behaviour. It is one of the first lines to move when a straight-run binder has been extended or has already aged. It is not a meaningful acceptance test on oxidized grades, which are deliberately low-ductility materials |
| Flash point | ASTM D92 or EN ISO 2592, Cleveland open cup, for paving and oxidized grades. ASTM D3143, Tag open cup, for cutbacks | The lowest temperature at which vapour above the sample ignites momentarily when a test flame passes over it | A low, falling or missing figure means volatiles are present: solvent contamination, cutter stock carry-over, or cracked material. It predicts a tank fire, refusal at a terminal and an insurance problem. Minima: 232 °C in ASTM D946, 230 °C in AASHTO M320, 220 °C in IS 73:2013, 260 °C at 70#, 50# and 30# in JTG F40. A cutback flash point reported against ASTM D92 is itself a finding |
| Solubility | ASTM D2042 in trichloroethylene; EN 12592 in toluene. The solvent is part of the result and must be named on the report, because a TCE figure is not an EN 12592 figure even at an identical limit | The proportion of the sample that dissolves — that is, the genuinely bituminous fraction. What stays on the filter is mineral matter or non-bituminous carbon | Below the limit, the drum contains something that is not bitumen. It predicts unpredictable mix behaviour, poor binder film integrity and a tonnage you overpaid for. Minimum 99.0 % in ASTM D946, EN 12591 and IS 73:2013; 99.5 % at 70# and 90# class A in JTG F40, where half a percentage point is the difference between five and ten tonnes of insolubles on a 1,000 tonne cargo. AASHTO M320 sets no solubility requirement at all, so on a performance-graded purchase the line exists only if the contract puts it there. Its absence from a certificate is the most informative omission on the page |
| Loss on heating and mass change | ASTM D1754, thin film oven test: 50 g in a flat-bottomed dish at 163 °C for 5 h on a rotating shelf. Or ASTM D2872, rolling thin film oven test: 163 °C for 85 minutes under a continuous air flow of 4000 mL per minute | The mass lost as volatiles leave, offset by the mass gained as the binder takes up oxygen. The two effects partly cancel, which is why the reported figure is a net change | A large loss predicts fume and smoke at the plant, hardening in the silo, and a binder that reaches the road already part-aged. JTG F40 limits the change to ±0.8 % in either direction and EN 12591 limits it to ±0.5 % at 50/70, which catches oxygen uptake as well as volatile loss — a one-sided maximum does not. Name the oven as well as the limit: ASTM D1754 and ASTM D2872 are different exposures and do not produce the same residue from the same binder |
| Retained penetration, or drop in penetration | ASTM D5 on the TFOT or RTFOT residue, expressed as a percentage of the original penetration | How much of the original softness survives simulated plant ageing. It is the closest thing a classical specification has to a durability measurement | The best single predictor of a pavement that cracks years before its design life. ASTM D946 requires minimum 52 % retained for grade 60-70 after ASTM D1754; EN 12591 requires minimum 50 % retained at 50/70 after EN 12607-1, plus a softening point of at least 48 °C on the residue; JTG F40 requires 61 % at 70# class A. A typical Middle East export sheet instead caps the drop at 20 %, which is 80 % retained and materially stricter, so establish which of the two your contract names. A percentage stated with no residue penetration behind it was written rather than measured |
| Viscosity ratio after RTFOT | IS 9382 or ASTM D2872 for the ageing, then ASTM D2171 for absolute viscosity at 60 °C before and after | How much stiffer the binder became during simulated mixing, expressed as a ratio of aged to original viscosity | IS 73:2013 caps it at 4.0 for every VG grade. A high ratio predicts rapid embrittlement and the same cracking failure that a low retained penetration predicts, measured in the viscosity system’s own currency instead of the needle’s |
| Ductility of the residue | ASTM D113 or IS 1208 run on the TFOT or RTFOT residue rather than on the original binder | Cohesion of the material as it will exist after the mixing plant, rather than as it arrived in the tank | IS 73:2013 requires 75, 50, 40 and 25 cm after RTFOT for VG-10 to VG-40 respectively; the requirement loosens as the grade hardens because harder binders are inherently less ductile. A failure here while original penetration still passes is the classic signature of a binder that will ravel |
| Kinematic viscosity at 135 °C | ASTM D2170 or IS 1206 Part 3. Rotational viscosity by ASTM D4402 in the performance system | Flow at the temperature at which the binder is pumped, sprayed through nozzles and mixed with aggregate | Too high and the binder cannot be pumped or will not coat aggregate without raising mixing temperature into the range where it ages prematurely; AASHTO M320 caps rotational viscosity at 135 °C at 3.0 Pa·s for exactly this reason. IS 73:2013 sets a minimum instead, because a binder too thin at 135 °C drains off the aggregate on the way to the paver |
| Specific gravity or density | ASTM D70 by pycnometer at 25 °C, EN 15326, or IS 1202 at 27 °C. Chinese practice reports it at 15 °C | Mass per unit volume | This is the number that converts the volume in a tank, a tanker or a flexitank into the weight on the invoice. A value outside the conventional band means either the material is not a conventional paving bitumen or mineral matter is present, and it invalidates every tonnage-to-volume calculation on the shipment. Chinese specifications require it to be reported rather than limited, for the same reason |
| Water content | ASTM D95, Dean and Stark distillation with a water-immiscible solvent | Water carried in the binder, reported by volume | Water predicts foaming and violent boil-over when a tank is heated through 100 °C, which is a personnel hazard rather than a quality defect. It is also a quantity fraud, because water is invoiced by weight along with the binder. A cap of 0.2 vol % is common export practice and is not an ASTM D946 requirement |
| Penetration index | Calculated from penetration and softening point, not measured. Not a requirement of ASTM D946 or EN 12591 | Temperature susceptibility — how sharply the binder changes consistency as temperature moves | Straight-run paving grades usually compute to between about −1 and +1. A value well above that on material sold as straight-run points to blown or blended component, or to two figures invented independently of each other. JTG F40 makes it a requirement rather than a check, with a window of −1.5 to +1.0 at 70# class A |
| Wax content | Distillation method under the Chinese test protocol. No requirement in ASTM D946 or EN 12591 | The mass of crystalline paraffinic material recovered from the sample, as a percentage of it | Wax stiffens the binder at low temperature where flexibility is needed and softens it at high temperature where stiffness is needed, and it migrates to the binder-aggregate interface. It decides the Chinese quality class at 2.2 %, 3.0 % and 4.5 % for classes A, B and C. An ASTM-based certificate normally carries no wax line at all, and that silence is not evidence of a low figure |
| Spot test | AASHTO T102, using a naphtha or naphtha-xylene solvent | Whether a drop of the solution spreads evenly on filter paper or leaves a dark centre spot | A positive spot indicates material that has been thermally cracked or severely overheated. It is an older screening test, retained on many export data sheets and largely superseded by solubility and the residue block, but it costs almost nothing to run and a positive result is worth an explanation |
If you can only argue about three lines in a specification, argue about the three that match the failure mode you actually face.
Softening point and viscosity at 60 °C. A binder at the soft end of its band in a 45 °C climate is the classic setup for wheel-track rutting. Push for the upper half of the softening point range.
Penetration, Fraass breaking point and BBR results. Harder is not always better — a 30/40 in a climate with cold nights will crack transversely no matter how well it resists rutting.
The TFOT or RTFOT residue lines: retained penetration, viscosity ratio and residue ductility. This group is the best early warning of a pavement that will fail years before its design life.
Solubility in trichloroethylene and specific gravity. Solubility below 99 % means something that is not bitumen is in the drum. Specific gravity ties the weight you paid for to the volume you received.
No standard binder specification line covers this reliably — adhesion depends on the binder and the local aggregate together. Where it matters, run a stripping test on the actual materials rather than trusting the certificate.
Flash point, by the correct method for the product. Cleveland open cup for paving and oxidized grades, Tag open cup for cutbacks. This is the line that governs storage, insurance and terminal acceptance.
Seven patterns that should slow a transaction down. None of them proves bad faith, and all of them deserve a question before shipment.
The remedy for all seven is the same: independent inspection at load port, with sampling supervised by the inspector and sealed retained samples held by both parties. Ask the inspection company for a quotation before the cargo is fixed, so the cost sits in the price rather than arriving as a surprise, and note what it buys — it converts every one of these questions from an argument after discharge into a document dated before shipment.
A specification does no work sitting in a data sheet. It does work when it is written into the sale contract in a form that decides, in advance, exactly which numbers apply, how they will be demonstrated, by whom, on what sample, and what happens if a result comes back outside them. Work through these ten points in order. Every one of them closes a gap that is otherwise argued about after discharge, at the moment when the buyer has the cargo and the seller has the money.
ASTM D946, EN 12591, IS 73:2013, AASHTO M320 or ASTM D6373, JTG F40-2004, GB/T 15180 — whichever governs, write it down. Then write the edition: either the year printed on the copy you are working from, or an express term that the edition current at the date of shipment applies. Standards are revised, limits move between editions, and a clause naming a standard without an edition is enforceable only to the extent the parties agree which document they meant. They will disagree precisely when it matters. Name one standard per property and never two, because two standards for the same property means two limits and a choice of which to argue.
60/70 to ASTM D946. VG-30 to IS 73:2013. PG 64-22 to AASHTO M320. 70# class A to JTG F40-2004, with the climate zone code of the project site. Do not write a grade from one system with a parenthetical equivalent from another: “60/70, VG-30 equivalent” creates two acceptance criteria and destroys the certainty the clause existed to create. If your project specification is written in one system and the available supply is graded in another, that is a decision to take before signature, not a footnote inside the contract.
Not just the grade-defining property. The qualifying properties are where substitution lives, and a schedule that lists only penetration has specified a quarter of the material. Decide deliberately where you want a two-sided limit rather than the one-sided floor the standard may set: a softening point minimum with no maximum permits a binder far stiffer than intended, which is exactly why GB/T 15180 sets a 44–54 °C window for AH-70 where JTG F40 sets a floor only. Where you quote a value tighter than the standard requires — a 250 °C flash point against the ASTM D946 floor of 232 °C, or a maximum 20 % drop in penetration against the standard’s minimum 52 % retained — state in words that the tighter figure governs, or you have written an ambiguity into the document.
A property without a method is a topic, not a specification clause. Flash point by Cleveland open cup (ASTM D92) and by Tag open cup (ASTM D3143) are different tests for different products and are not interchangeable. Penetration by ASTM D5, EN 1426 and IS 1203 are closely aligned but the report should say which was run. Solubility by ASTM D2042 uses trichloroethylene and by EN 12592 uses toluene, and results in different solvents are not interchangeable even where the limit is the same 99.0 %, so the solvent must appear. Ageing by ASTM D1754 and by ASTM D2872 are different exposures and produce different residues, so a residue limit that does not say which oven produced it cannot be enforced.
Name the practice: ASTM D140, AASHTO T 40 or EN 58. State who draws the sample, from where, and how many increments — drawn across the lot rather than from the drums nearest the container door, and taken through the loading operation rather than as a single grab for bulk. State how each sample is sealed, labelled and dispatched. Then require sealed retained samples, drawn by the appointed inspector in the presence of both parties, split and held by each side for an agreed period after discharge. Without a retained load-port sample, a quality dispute found at the plant is unwinnable, because the seller will say the material aged or was contaminated after delivery and nobody can prove otherwise. The sampling procedure page sets out the increment counts and sealing detail in full.
Three test results can legitimately exist for one cargo: the producer’s own laboratory at production, an independent laboratory on a sample drawn by an inspector at load, and the buyer’s laboratory at discharge. They will not be identical, and a contract that does not say which one is the acceptance test has left the most consequential question open. Name it. Require the testing laboratory to be identified by name, address and contact route on the report. Where the cargo value justifies it, require accreditation to ISO/IEC 17025 and check that the specific tests appear inside the accreditation scope, in the public register of the accreditation body, rather than accepting the certificate as presented.
Two competent laboratories testing the same material will not report the same number, and every ASTM and EN method publishes a precision statement saying how much difference is normal. ASTM D3244 is the practice for using that precision statement to combine a supplier result and a receiver result into a single assigned test value, which turns a stand-off into a calculation. Name it, name a referee laboratory or the mechanism for choosing one, and state who pays for the retest in each outcome. A counterparty who declines to accept a published resolution practice is telling you what they expect an independent retest to show.
State what happens when a result lands outside a limit: rejection, replacement, a price adjustment on a stated scale, or acceptance under written waiver. Then say which remedy attaches to which line, because they are not equivalent failures. A solubility result below 99.0 % is categorical — the material is not what was sold. A softening point one degree outside a window on a cargo that passes everything else may be a commercial conversation. Writing the distinction in advance is what stops both parties from taking the maximalist position later.
Require the batch or lot number to appear on the Certificate of Analysis, on the packing list, on the drum markings and on the inspection certificate, and require them to agree. Require the Certificate of Analysis to carry the sampling date and practice, test dates separate from the issue date, the method beside every value, the units the specification uses, and a named signatory with a role. Require it to be issued and received before payment rather than travelling with the cargo, since a certificate that arrives with the goods arrives after the only moment at which it could have changed a decision.
“Or equivalent”. “Approximately”. “Typical values”. “As per international standard”. “Refinery standard specification”. “Subject to availability of grade”. Each of these moves the acceptance criterion out of the document and into an argument, and each of them is usually inserted by whoever expects to need the room. If a tolerance is genuinely intended, write the tolerance as a number. If a substitution might genuinely be needed, write who may approve it, in what form and by when — which in practice means the engineer or specifying authority for the project, in writing, before shipment.
The governing standard is ASTM D946 or AASHTO M20, and it requires penetration 60–70 dmm at 25 °C (ASTM D5), ductility at 25 °C minimum 100 cm (ASTM D113), flash point minimum 232 °C (ASTM D92), solubility minimum 99.0 % (ASTM D2042) and minimum 52 % retained penetration on the thin film oven residue. Export data sheets then add lines the standard does not contain: softening point 49–56 °C (ASTM D36), which ASTM D946 does not require at all, a flash point minimum of 250 °C, a maximum 20 % drop in penetration and specific gravity 1.01–1.06 (ASTM D70). Both sets of figures are legitimate; what matters is which document the contract names, because that is the one that will be enforced.
IS 73:2013, published by the Bureau of Indian Standards. It defines VG-10, VG-20, VG-30 and VG-40 by absolute viscosity at 60 °C and specifies ageing by the rolling thin film oven test rather than the thin film oven test.
Export technical data sheets often quote tighter values than the governing standard requires — a flash point minimum of 250 °C against the ASTM D946 floor of 232 °C, for example. Exceeding a standard is not a conflict. What matters is which document the contract cites, because that is the one that will be enforced.
It tells you what proportion of the material is genuine bitumen. True bitumen dissolves in trichloroethylene; mineral filler and heavy inorganic residues do not. A minimum of 99.0 % is standard, and a result below it means the drum contains something other than bitumen.
Yes, for any paving application. The TFOT or RTFOT residue lines are the best available predictor of how the binder will behave after hot mixing and through its service life. A certificate without them has left out the durability half of the specification.
Oxidized grades are specified by softening point and penetration — 85/25 means a softening point around 80–90 °C and penetration around 20–30 dmm. ASTM D312 covers oxidized asphalt for built-up roofing in four types by softening point band. Ductility is not a meaningful acceptance test for these products.
It can be written that way, but it should not be. "Or equivalent" leaves the acceptance criteria undefined and puts the buyer in a weak position if the delivered material underperforms. Name the grade, name the governing standard and name the inspection arrangement.
The engineer or specifying authority for the project, in writing, before shipment. A supplier cannot approve a substitution against a specification they did not write, and a verbal agreement with a site contact will not survive the handover testing.
No, and no factor or formula exists to do it. The systems measure different physical quantities, at different temperatures, on differently aged material. Penetration is a depth under a fixed load at 25 °C; a viscosity grade is set by absolute viscosity at 60 °C in poise; a performance grade is a set of rheological criteria at temperatures the grade name itself dictates, measured on RTFOT and PAV residues. IS 73:2013 also sets only a minimum penetration for VG-30 — 45 dmm — and no maximum, so two compliant VG-30 cargoes can be far apart on the needle. A cargo holds a designation in a system only once it has been tested in that system. Nearest-neighbour equivalence tables are for shortlisting what to ask for and then test, not for writing into a contract.
Six things. The standard and its edition, or an express term that the current edition at the date of shipment applies. The grade, written in that standard's own vocabulary and not cross-quoted from another system. The full property schedule with a minimum and a maximum on every line, including the qualifying properties. The test method beside every value, including the apparatus where it matters — Cleveland open cup against Tag open cup, TFOT against RTFOT. The sampling basis: which practice, who draws, from where, and sealed retained samples split between the parties. And who tests, when, which result governs acceptance, and how a disagreement between two laboratories is resolved. Anything left out becomes a negotiation at the moment you have the least leverage, which is after discharge.
Two pages deal with problems that arise before a specification is even read.
Send the specification document with your quantity, packing and destination. The offer will be checked line by line against it, and anything that cannot be met will be stated plainly rather than left for the Certificate of Analysis to reveal later.