VG-10 is the softest of the four paving grades in IS 73:2013, defined by absolute viscosity at 60 °C — nominally 1000 poise, with an accepted band of 800 to 1200 poise.
The designation is a laboratory instruction rather than a trade description. Under IS 1206 (Part 2) — the Indian counterpart of ASTM D2171 — a conditioned sample is brought to 60 °C in a bath, loaded into a vacuum capillary viscometer, and pulled through the capillary by a measured partial vacuum while the laboratory times its passage between etched marks. Multiplying that time by the tube's calibration factor gives absolute viscosity in poise. A result inside 800 to 1200 poise is grade VG-10. The 10 in the grade name is that band's midpoint counted in hundreds of poise: 1000, give or take 200. Converted, the band is 80 to 120 Pa·s.
Two temperatures do all the work in IS 73:2013. 60 °C stands in for a dark pavement surface at the hottest part of a summer afternoon, so grading there speaks directly to resistance to permanent deformation. 135 °C stands in for pumping, spraying and mixing conditions, so the second viscosity line speaks to what happens in the plant and on the distributor bar. On VG-10 the second figure carries more weight than it does for any other grade in the family, because a large share of VG-10 is never mixed with aggregate at all — it is sprayed, or it is fed into a colloid mill or a cutback blending tank.
Buyers arriving from the penetration market frequently read the softest grade as the cheapest or the least demanding one. IS 73:2013 says the opposite. VG-10 carries the highest penetration floor in the standard at 80 dmm — VG-20 requires 60, VG-30 requires 45 and VG-40 requires only 35 — and the most demanding residual ductility requirement at 75 cm after rolling thin film oven ageing, three times what VG-40 has to reach. The grade is soft because the applications it serves need a binder that stays extensible in a thin film. It is not permitted to be soft and short at the same time.
Read the four viscosity bands in sequence and one feature stands out. VG-10 runs up to 1200 poise and VG-20 begins at 1600. Between those two figures IS 73:2013 grades nothing at all. A batch measuring 1400 poise at 60 °C is not a marginal VG-10 and not a soft VG-20 — it sits outside the standard. That is a different situation from the hard end of the range, where the VG-30 and VG-40 bands overlap between 3200 and 3600 poise and a single measured viscosity can satisfy either grade. On VG-10 there is no room for a close-enough argument: the measured figure is inside 800 to 1200 poise, or the cargo is not VG-10.
IS 73:2013 applies the same ageing limit to every grade — the viscosity ratio at 60 °C after the rolling thin film oven test may not exceed 4.0. Applied to VG-10 the arithmetic deserves a moment of attention. A batch delivered at 800 poise is permitted to reach 3200 poise after simulated short-term ageing, and a batch delivered at 1200 poise is permitted to reach 4800 poise. Those two figures are exactly the bottom and the top of the VG-40 band. A VG-10 that ages to the maximum the standard allows finishes as stiff as the hardest paving grade in the same standard.
The ratio is an index of ageing susceptibility rather than a prediction of what any particular road will experience — a VG-10 sprayed in a surface dressing never passes through a mixer at all. But it tells you how the binder responds to heat and oxygen, and for a grade that is routinely held hot in a tank, sprayed at the top of its temperature range, re-melted out of drums at destination, or fluxed and stored as a cutback, that is precisely the property worth knowing. It is also why the standard pairs the ratio with a 75 cm residual ductility floor. Together the two lines say the binder may harden, but it may not become brittle while doing so.
The standard contains four paving grades, running from soft to hard as the number rises, because the number tracks viscosity directly rather than inversely as penetration does:
India retired penetration grading when IS 73 was revised in 2006, and the 2013 edition is the one in force today. VG-10 took over from the old S-90 and A-90 penetration grades, which is why a legacy tender document still naming S-90 is normally satisfied today by VG-10 — provided the certificate carries viscosity data rather than only a penetration figure.
Eight requirements, and that is the whole of what IS 73:2013 asks of VG-10. They are set out below in the order and format an export technical data sheet uses, with the Indian method and its international counterpart against each line.
| Property | Test method | Unit | Min | Max |
|---|---|---|---|---|
| Absolute viscosity at 60 °C | IS 1206 (Part 2) / ASTM D2171 | poise | 800 | 1200 |
| Kinematic viscosity at 135 °C | IS 1206 (Part 3) / ASTM D2170 | cSt | 250 | — |
| Penetration at 25 °C, 100 g, 5 s | IS 1203 / ASTM D5 / EN 1426 | dmm (0.1 mm) | 80 | — |
| Softening point, ring & ball | IS 1205 / ASTM D36 / EN 1427 | °C | 40 | — |
| Flash point, Cleveland open cup | IS 1448 (P:69) / ASTM D92 | °C | 220 | — |
| Solubility in trichloroethylene | IS 1216 / ASTM D2042 | wt % | 99.0 | — |
| Viscosity ratio at 60 °C, on RTFOT residue | IS 9382 / ASTM D2872, then IS 1206 (Part 2) | ratio | — | 4.0 |
| Ductility at 25 °C, 5 cm/min, on RTFOT residue | IS 1208 / ASTM D113 | cm | 75 | — |
IS 73:2013 controls VG-10 with eight requirements. Two of them — the penetration floor and the ductility floor on aged residue — are pitched harder on this grade than on any other in the standard, while the 60 °C viscosity and the two results taken after rolling thin film oven ageing are the lines a thin certificate quietly leaves out. Work through what each line is actually guarding against and you know which one to challenge when a result comes back close to a limit.
800 to 1200 poise by IS 1206 (Part 2) or ASTM D2171 — the one two-sided limit in the table, and the only line that actually classifies the cargo. The other seven are there to catch a binder that reaches the right band for the wrong reasons. Omit this measurement and no combination of the remaining results can show that a parcel is VG-10 rather than something that merely resembles it. That gap bites harder on the soft grade than on the hard ones, because the two properties a buyer can check quickly and cheaply — penetration and softening point — are precisely the properties on which a genuine VG-10 and an ordinary soft penetration-grade bitumen look alike.
Measured by gravity flow through a capillary viscometer to IS 1206 (Part 3) or ASTM D2170. The 250 cSt minimum is the lowest of the four grades, and like the others it is written as a floor rather than a ceiling. The reasoning is that the 60 °C band has already fixed how stiff the binder will be inside the pavement, which leaves the 135 °C floor to police the other end of the curve: it rejects material that reads correctly at service temperature and then thins out too far once it is heated for work. On VG-10 that guard earns its keep, because pulling a heavier residue down into an 800 to 1200 poise band by fluxing is a cheaper route to the grade than producing to it, and the result sprays badly, drains off chippings and emulsifies inconsistently.
IS 1203, the same test as ASTM D5 and EN 1426. Eighty dmm is the highest penetration minimum in IS 73:2013 and it does two jobs at once. It excludes stiff material that has been dragged into the viscosity band with a diluent, and it puts a floor under the low-temperature flexibility that spray seals and emulsion residues depend on. There is no upper limit, so a fully compliant VG-10 batch may report 95 or 110 dmm. Buyers who want an 80/100-style ceiling should understand they are adding a requirement the standard does not contain. That is entirely legitimate on a manufacturing feedstock where batch-to-batch consistency matters, but it has to be written into the contract rather than assumed.
Ring and ball, IS 1205 or ASTM D36, and the lowest floor in the family: 40 °C against 45 for VG-20, 47 for VG-30 and 50 for VG-40. This line is the clearest statement of what VG-10 is not. A binder permitted down to 40 °C has no business carrying channelised heavy traffic on a hot-climate carriageway, and no mix design compensates for that. Paired with penetration it also does authenticity work at almost no cost. VG-10 is the only grade in the standard that combines a high penetration floor with a low softening point floor, so a genuine straight-run parcel normally clears both with room to spare. The combination to question is a high softening point sitting beside a penetration hovering at 80 dmm, because air-blowing lifts softening point far faster than it drives penetration down. Blown residue can be coaxed into looking like a soft paving binder on a data sheet and then behaves nothing like one in a seal or in a colloid mill.
Cleveland open cup, IS 1448 (P:69) or ASTM D92. IS 73:2013 applies the same 220 °C floor to all four grades and production material normally tests well above it. Two points are specific to VG-10. First, the grade is sprayed, and spraying is done near the top of its working temperature range, so the margin between operating temperature and the flash point floor is narrower here than in mixing work. Second, and far more important: once VG-10 has been fluxed into a cutback, the flash point of the finished product is a completely different number measured by a different method — Tag open cup, ASTM D3143 — and it is far lower. The 220 °C figure belongs to the base binder and travels no further than the blending tank.
Measured to IS 1216 or ASTM D2042. The sample is dissolved in trichloroethylene and no more than one part in a hundred may be left behind; whatever fails to dissolve was never bitumen in the first place. On VG-10 the line does more work than it does on a hard grade. Soft material is the easiest stock in the trade to bulk out with mineral filler, and a needle dropped into an extended soft binder will still return a plausible penetration figure, so solubility is frequently the only line on the certificate that catches it. The test is quick and cheap, which makes its absence a finding rather than an oversight.
A film of binder is rolled and heated in an oven to IS 9382, the Indian equivalent of ASTM D2872, after which the aged residue goes back into the vacuum capillary viscometer and its 60 °C viscosity is expressed as a multiple of the original figure. The Indian standard calls for the rolling test, not the older static thin film oven test, so a TFOT result — or a loss-on-heating and retained-penetration pair — is not a substitute line on an IS 73:2013 certificate. It may describe perfectly good bitumen, but it does not evidence compliance with the standard the buyer named. A ratio close to 4.0 on a VG-10 tells you the binder hardens rapidly under heat and air, which is a poor property in a grade that is held hot, sprayed, and in drum trade re-melted at destination before it is ever used.
Measured to IS 1208 or ASTM D113 by stretching a briquette of the aged residue at 5 cm/min until the thread breaks. Seventy-five centimetres is the most demanding residual ductility requirement in IS 73:2013 — VG-20 requires 50 cm, VG-30 requires 40 cm and VG-40 only 25 cm — and it is the line that defines the character of the grade. A soft binder that has lost its stretch after ageing is not really a soft binder; it is a heavier stock that was fluxed into the band, and it will disappoint as a seal binder and as an emulsion base. If one line on a VG-10 certificate is worth insisting on, it is this one. One caution on arithmetic. This 75 cm is measured after ageing, whereas the 100 cm minimum printed on penetration-grade export sheets is measured on binder straight from the tank. They are not the same test on the same material, and a tender evaluation that ranks a 100 cm unaged figure above a 75 cm aged one has compared nothing at all.
All eight lines above, each with a measured number and the test method named beside it, on a batch-specific document. Gaps tend to appear in the same two places: the 60 °C viscosity, because a vacuum capillary bench is a far larger investment than a penetrometer and many road laboratories simply do not own one, and the RTFOT pair, because the oven run and the follow-on tests consume both time and sample. Where those are absent, what you are holding is a penetration-grade certificate with a viscosity-grade heading typed above it. Chase the missing lines while the cargo is still at load port, and on a feedstock purchase in particular have an independent inspector draw and seal retained samples that both parties hold, so a later laboratory result can be tied back to the parcel it came from instead of argued over. The certificate of analysis reference sets out what a complete document looks like, and the test methods reference describes each procedure.
The whole standard in one table, with VG-10 in the leftmost column. What it shows is that softest does not mean loosest: on two of the eight lines — penetration and post-ageing ductility — VG-10 is held to a far tighter requirement than VG-40, and its viscosity band is the narrowest in the standard at 400 poise wide. That is the reverse of what most buyers arriving from the penetration market expect.
| Requirement | VG-10 | VG-20 | VG-30 | VG-40 |
|---|---|---|---|---|
| Absolute viscosity at 60 °C, poise | 800–1200 | 1600–2400 | 2400–3600 | 3200–4800 |
| Kinematic viscosity at 135 °C, cSt, min | 250 | 300 | 350 | 400 |
| Penetration at 25 °C, dmm, min | 80 | 60 | 45 | 35 |
| Softening point, ring & ball, °C, min | 40 | 45 | 47 | 50 |
| Flash point, Cleveland open cup, °C, min | 220 | 220 | 220 | 220 |
| Solubility in trichloroethylene, %, min | 99.0 | 99.0 | 99.0 | 99.0 |
| Viscosity ratio at 60 °C after RTFOT, max | 4.0 | 4.0 | 4.0 | 4.0 |
| Ductility at 25 °C on RTFOT residue, cm, min | 75 | 50 | 40 | 25 |
| Typical role in Indian practice | Spray applications and surface dressing, paving in the coldest zones, feedstock for emulsion and cutback manufacture | Paving in cold climate zones and under lighter traffic | The general-purpose paving grade across most of the country | Highly stressed and high-temperature heavy-duty pavements |
The soft grade earns its place in three distinct ways: sprayed as a binder in its own right, laid in hot mix where cracking rather than rutting is the dominant risk, and bought as raw material by plants that make something else out of it.
Sprayed hot through a distributor bar onto an existing surface, with chippings spread and rolled into it while the binder is still live. The binder has to wet the stone, hold it through the first winter and stay extensible under a moving substrate — the exact profile the 80 dmm penetration floor and the 75 cm residual ductility floor describe.
Sand seals, the sprayed binder layers in penetration macadam construction, and the sealing coat over an open-graded premix carpet. Spraying demands a far lower binder viscosity than mixing does, which is why the grade with the lowest viscosity band and the lowest 135 °C floor is the one chosen.
Bituminous concrete and dense bituminous macadam in the coldest regions, where low-temperature cracking rather than summer rutting decides pavement life. Grade selection under Indian practice is keyed to site air temperature and commercial traffic volume, and VG-10 sits at the cold, lightly trafficked end of that decision.
Feed to a colloid mill for cationic and anionic emulsions used in tack coats, prime coats, slurry seals and micro-surfacing. The residue left on the road after the water leaves is the base binder and nothing else, so the base grade is what determines how the seal performs.
Fluxed with a kerosene-type diluent to produce the medium-curing MC series — MC-30 for priming a granular base, MC-70 and heavier grades for tack and premix work. The properties of the residue after distillation are inherited directly from the VG-10 that went in.
Hand-laid open-graded premix carpet, pothole repair and rural road work where the plant is small, the haul is long and the crew needs the mix to stay workable. A soft binder buys a wider roller window, which on this kind of work is worth more than stiffness.
IS 73:2013 names emulsion and cutback manufacture among VG-10's assigned uses, which puts this grade in an unusual position: a large part of it is bought by plants that never lay it as a binder at all. It is raw material, and that changes what the buyer has to specify.
An emulsion and a cutback solve the same problem in different ways: both make bitumen temporarily fluid at low temperature, one by dispersing it in water and one by dissolving it in a petroleum solvent. In both cases the carrier eventually leaves, and what remains on the road is the base binder and nothing else. That residue has to bond a chipping, hold a tack coat or seal a surface through a full temperature cycle, and it has to do it in a thin film with no aggregate skeleton supporting it. A residue that is stiff and short cracks and sheds stone. That is the entire argument for using the softest grade in the standard as feedstock, and it is why IS 73:2013 puts the VG-10 residual ductility floor at 75 cm rather than the 25 cm it accepts on VG-40.
A bitumen emulsion is made by shearing hot binder into an aqueous phase in a colloid mill. The water phase carries an emulsifier — for cationic emulsions an amine-type surfactant, acidified so the droplets take a positive charge, which is why cationic grades bond well to the negatively charged surfaces of most aggregates. Indian practice specifies cationic bitumen emulsions under IS 8887; the corresponding ASTM specification is D2397. Grades are named for how quickly they break: rapid setting for chip seals and surface dressing, medium setting for premix work, slow setting for tack coats, prime coats and slurry seal.
Binder content is typically in the range of 55 to 70 % by mass, which means between roughly a third and a half of the finished product is water. That single fact drives a commercial decision that comes up constantly on this grade. Importing finished emulsion means paying ocean freight on water, and accepting a product with a limited storage life that settles if it is not agitated and that is damaged outright if it freezes. Importing VG-10 and running a local emulsion plant means shipping only the binder. For a buyer with steady emulsion demand and somewhere to mill it, the arithmetic usually favours importing the base grade.
Temperature control at the mill is a pairing exercise rather than a single setpoint. The binder enters hot and the soap solution enters warm, and the two temperatures are chosen together so that the emulsion leaving the mill stays below 100 °C at atmospheric pressure. Push the combination too high and the emulsion boils in the line; too low and the binder is too viscous to shear into droplets of the right size distribution. This is another place a soft base grade helps directly: VG-10 reaches milling viscosity at a lower temperature than VG-30 does, which widens the workable window on both sides.
A cutback is base bitumen fluxed with a petroleum distillate. The medium-curing MC series uses a kerosene-type diluent and is specified in ASTM D2027. The grade number is the lower limit of the kinematic viscosity range at 60 °C in centistokes, and each grade spans that number to twice that number: MC-30 is 30 to 60 cSt, MC-70 is 70 to 140 cSt, MC-250 is 250 to 500 cSt and MC-800 is 800 to 1600 cSt. The lower the number the more diluent in the blend and the more deeply the product penetrates, which is why MC-30 is the usual prime coat on a granular base while the heavier grades go to tack and premix work.
Two consequences follow for the buyer of the base grade. The first is that the properties of the distillation residue are inherited directly from the VG-10 that went in, so the base specification is not a detail — it is the product specification, one step removed. The second is safety. Adding a volatile diluent to hot bitumen is the most hazardous operation this grade is involved in anywhere in its life. The flash point of the finished cutback is measured by Tag open cup to ASTM D3143 and sits far below the 220 °C Cleveland figure of the base binder. Solvent is introduced below the liquid surface rather than sprayed onto it, the base binder temperature is brought down and held before blending starts, and the blending tank is treated as a flammable-liquid installation from that point on.
A paving contractor needs each cargo to meet the standard. A manufacturer needs each cargo to meet the standard and to resemble the last one, because emulsion recipes and cutback blend ratios are tuned to a particular base. Three practical points follow:
A VG-10 enquiry usually arrives written in someone else's rule book — an ASTM-based tender, a European penetration band, a legacy Indian document naming a grade withdrawn two decades ago, or a project that specifies performance grades. This table lines them up and says how far each comparison can honestly be pushed.
| System | Standard | Nearest counterpart to VG-10 | What that actually means |
|---|---|---|---|
| Viscosity grading (US) | ASTM D3381 / AASHTO M 226 | Grade AC-10 | The only genuine like-for-like counterpart VG-10 has. D3381 grades AC-10 on absolute viscosity at 60 °C at 1000 poise plus or minus 200 — numerically the same 800–1200 window, produced by the same measurement at the same temperature. The two standards part company on everything around it, because D3381 writes its own supporting requirements, so an AC-10 certificate evidences the grading parameter and not IS 73:2013 compliance |
| Penetration grading (US) | ASTM D946 / AASHTO M 20 | Grade 85-100, with 120-150 material also frequently landing inside the VG-10 viscosity band | Not equivalent. D946 fixes a two-sided penetration band and never measures viscosity at 60 °C, while IS 73:2013 fixes the viscosity band and applies only an 80 dmm penetration floor. An 85/100 cargo does not automatically pass VG-10 |
| Penetration grading (Europe) | EN 12591 | 70/100 and 100/150 | VG-10 straddles the boundary between the two European bands, because it sets a penetration floor and no ceiling. EN 12591 contains no absolute viscosity requirement at 60 °C, so treat the comparison as an indication of consistency only |
| Old Indian penetration grades | IS 73:1992 (withdrawn) | S-90 / A-90 | The 80–100 penetration grade that VG-10 replaced when India moved to viscosity grading. Still quoted in legacy tender language and in older project documents, and normally satisfied today by VG-10 |
| Performance grading | AASHTO M 320 | Cannot be inferred from viscosity | PG designations come from DSR on original, RTFO and PAV residue plus BBR at the low-temperature end. A 60 °C viscosity figure does not produce one, and where a project names a PG grade only PG test data satisfies it |
A soft grade needs less heat than a hard one and gains nothing from more, so the most common error on VG-10 is running it at temperatures borrowed from a VG-30 procedure. The spraying and blending lines below have no equivalent on the harder grades.
| Operation | Typical range | What it controls, and what goes wrong outside it |
|---|---|---|
| Storage, short term | 140–160 °C | Enough to keep the binder mobile without spending its ageing budget in the tank. VG-10 reaches pumpable viscosity at lower temperature than any other grade in the family |
| Storage, long term | below 140 °C | Prolonged hot storage raises viscosity at 60 °C. The VG-10 band is only 400 poise wide, and there is no grade at all between 1200 and 1600 poise, so a drifted batch falls out of the standard rather than into the next grade up |
| Pumping and circulation | 130–160 °C | Below roughly 130 °C line losses climb and pumps begin to cavitate. Above the range there is no benefit, only oxidation |
| Spray application, surface dressing | 160–175 °C | Spraying needs a much lower binder viscosity than mixing does, so this is the hottest routine operation on the grade. The distributor bar sets the figure, and it has to be read against the 220 °C flash point floor rather than assumed to be safe |
| Aggregate at the mixer | 145–170 °C | Aggregate carries most of the heat into a hot mix. Too cold and the binder film chills on contact leaving fines uncoated; too hot and it scorches the film |
| Mixing with aggregate | 140–160 °C | Complete coating is achieved at lower temperature than a VG-30 mix needs. Running a VG-10 mix at VG-30 temperatures burns fuel and ages the binder for no gain in coating |
| Delivery at the paver | above 125 °C | Verify this at the paver, not at the plant. The soft grade is more forgiving of a long haul than a hard grade, which is a large part of why it is chosen for remote and cold-weather work |
| Compaction, start | 125–140 °C | Rolling can begin lower than on a hard-grade mat and the mat stays workable longer, which widens the roller window rather than compressing it |
| Compaction, cut-off | above 80–90 °C | Lower than the cut-off for a hard grade. Below it further passes rearrange nothing and only polish the surface |
| Feed to an emulsion colloid mill | typically 120–150 °C | Chosen as a pair with the soap solution temperature so the emulsion leaving the mill stays below 100 °C at atmospheric pressure. Too cold and the binder will not shear into droplets of the right size |
| Blending into a cutback | controlled and well below the flash point of the finished blend | The most hazardous operation this grade is involved in. Diluent is introduced below the liquid surface, never sprayed onto it, and the base binder is cooled and held before blending starts |
| Target binder viscosity for mixing | 170 ± 20 cSt | The viscosity rule that sits behind every temperature figure above. Read the temperature off the batch viscosity–temperature chart rather than off a table |
| Target binder viscosity for compaction | 280 ± 30 cSt | The same principle applied to the roller window |
| Absolute ceiling | do not exceed 180 °C | Rapid oxidation and heavy fuming, and on a grade that is already sprayed at 175 °C the 220 °C flash point floor is closer than most operators assume |
It is the 800 to 1200 poise grade of IS 73:2013. The letters name the grading system — viscosity rather than penetration — and the figure is the nominal absolute viscosity at 60 °C counted in hundreds of poise, so VG-10 is built around 1000 poise with a tolerance of plus or minus 200, which is 80 to 120 Pa·s in SI units. IS 1206 (Part 2) is the method, and ASTM D2171 is its international twin. What separates VG-10 from the other three grades is not only that it is the softest. It is the one grade in the standard whose assigned uses are mostly not hot-mix paving: IS 73:2013 points it at spray work and surface dressing, at paving in the coldest zones, and at the emulsion and cutback plants that buy it as raw material rather than as a finished binder.
IS 73:2013 requires a minimum of 80 dmm at 25 °C by IS 1203 and sets no ceiling at all. That 80 dmm floor is the highest in the standard — VG-20 requires 60, VG-30 requires 45 and VG-40 only 35. In a viscosity-graded standard the needle is not what classifies the material, so the floor is free to do two narrower jobs instead: it shuts out a heavier stock that has been fluxed down into the 800 to 1200 poise band, and it underwrites the low-temperature flexibility that seals and emulsion residues live on. A compliant VG-10 batch may well report 95 or 110 dmm. If your process needs a ceiling, write one into the contract, because the standard does not contain one.
No, and the pairing is quoted far more loosely than it deserves. The two grades are not even measured at the same temperature. An 80/100 specification fixes a two-sided penetration band at 25 °C; VG-10 fixes a viscosity band at 60 °C and then puts only a floor under penetration. That asymmetry means a soft penetration-grade parcel is not VG-10 until absolute viscosity has actually been run on it and come back inside 800 to 1200 poise — and equally, a compliant VG-10 reading 105 dmm would be rejected against an 80/100 or 85/100 specification for being too soft, while having nothing to answer for under its own standard. In practice a good deal of 80/100 and 85/100 production does land inside the VG-10 viscosity band, but landing there has to be shown on the batch certificate, not assumed from the grade name. The real like-for-like is ASTM D3381 grade AC-10, graded at 1000 poise plus or minus 200 by the same test at the same temperature.
Because extensibility is the property VG-10 is bought for. The grade goes into surface dressings, seals and emulsion residues, where a thin film of binder has to hold a chipping and follow the movement of the layer underneath with no aggregate skeleton carrying the load. A soft binder that has lost its stretch after ageing is not a soft binder at all — it is usually a heavier stock that was fluxed into the viscosity band, and it will shed stone and crack. A hard grade is allowed a much lower figure because a stiff binder legitimately has less elongation left after ageing. Read the 75 cm requirement alongside the maximum viscosity ratio of 4.0: together they say the binder may harden through the plant, but it may not become brittle while doing so.
In cold climate zones, yes — it is a paving grade and Indian practice uses it for bituminous mixes in the coldest regions, where low-temperature cracking rather than summer rutting decides pavement life. In a hot climate under heavy or channelised traffic it is the wrong choice, and the softening point line makes that plain: a binder permitted down to 40 °C will deform under load on a surface that reaches 60 °C. Grade selection under Indian practice is keyed to site air temperature and commercial traffic volume, and the answer for a hot-climate highway is VG-30, stepping up to VG-40 where traffic is slow, heavy or standing.
Because the carrier leaves and the base binder is what stays on the road. In an emulsion the water evaporates and the residue is the binder; in a cutback the diluent distils off and the residue is the binder. That residue has to bond aggregate and stay flexible in a thin film, which is exactly the property profile the 80 dmm penetration floor and the 75 cm residual ductility floor describe. There are two practical benefits as well: VG-10 reaches milling viscosity at a lower temperature than a harder grade, which widens the working window at the colloid mill, and it needs less diluent to reach a given cutback viscosity, which reduces both solvent cost and the volume of hydrocarbon that has to evaporate on site.
Six results on the binder as supplied — absolute viscosity at 60 °C, kinematic viscosity at 135 °C, penetration at 25 °C, softening point, flash point and solubility in trichloroethylene — plus two taken on the rolling thin film oven residue, namely the viscosity ratio at 60 °C and the ductility at 25 °C, each with its method printed alongside. Three things then matter beyond the eight lines simply being present. The document has to be tied to your batch or tank number rather than to the product in general. The figures have to be measured, not the specification column copied downward; numbers landing exactly on the limits shipment after shipment describe a template rather than a parcel. And on VG-10 specifically, read where inside 800 to 1200 poise the batch actually falls, because an emulsion or cutback plant tunes its recipe to that position and not to the band. The Technical Data Sheet, Safety Data Sheet and Certificate of Origin belong in the same file, and on any parcel destined for a manufacturing plant an independent load-port inspection of quality, quantity and packing condition is worth buying rather than waiving.
It changes what you watch, in both directions. VG-10 melts out of a drum considerably faster than a hard grade and needs less heat to do it, which is a genuine advantage at a site without a large melting unit and removes the temptation to force the job with direct flame. Against that, a soft binder is more sensitive to how the cargo is stored: drums should stand upright on a level surface under cover, stacking should be kept conservative, and drums left in direct sun on a hot apron can deform under load. The same caution applies to jumbo and poly bags, which hold shape less well with a soft binder in hot storage. Loading figures are unaffected by grade — a 20-foot container typically takes about 80 drums, giving roughly 12 MT at 150 kg net per drum or about 14.4 MT at 180 kg, with exact counts depending on drum dimensions and any destination weight limit. Specify new steel drums explicitly; reconditioned drums are the most common source of contamination disputes, and contamination matters more on a feedstock grade than on a paving grade because it carries straight through into the emulsion or the cutback.
Send quantity, packing, destination port and Incoterm. Say whether the cargo is for spray and paving work or as feedstock for an emulsion or cutback plant — the certificate content and the batch-to-batch consistency that matter are different in each case, and the offer will be built around the one you actually need.