Cutback Bitumen MC 800 — Specification, Production & Applications
Cutback Bitumen MC 800 is a medium-curing, kerosene-cut binder of 800–1600 mmآ²/s at 60آ°C, bought by cold-mix producers and road maintenance authorities who need a coating grade rather than a priming grade.
Reading the grade
What fixes the grade is kinematic viscosity at 60آ°C measured to ASTM D2170: 800–1600 mmآ²/s, the designation being the lower bound and the ceiling exactly twice it. That places MC 800 between MC 250 (250–500) and MC 3000 (3000–6000). Viscosity is bought by leaving solvent out, so the minimum residue by distillation climbs with the grade — around 67% for MC 250, 75% here. But the 225آ°C and 260آ°C distillation limits tighten as well, which means the kerosene cut itself is heavier, not merely scarcer. MC 800 is a different solvent as well as a different dose.
What buyers should know
Practically, MC 800 is a mixing and spraying grade, not a prime. It will not soak into an untreated granular base the way MC 30 and MC 70 do; applied as a prime it bridges the surface, stays there, and is picked up by construction traffic. Its working range is coating aggregate at ambient temperature for road mix, cold plant mix and stockpile patching, plus single-application surface treatment where ambient temperatures are high enough that a lighter grade would run off camber. Choosing between MC 250 and MC 800 is usually a choice about aggregate grading and site temperature.
How Cutback Bitumen MC 800 is produced
Feedstock and process
MC 800 is blended rather than refined as such. The starting point is a soft penetration-grade base chosen so the recovered residue lands inside the specified penetration window at 25آ°C — in practice a 180/200 or 200/300 straight-run vacuum residue, or a harder grade fluxed back with a heavy distillate. Air-blown bitumen cannot be used. Oxidation raises the asphaltene fraction and collapses ductility, and the residue specification demands at least 100 cm at 25آ°C to ASTM D113; a blown binder of the same nominal penetration would fail that test outright. The 99% minimum solubility in trichloroethylene to ASTM D2042 further rules out filled or extended feedstocks.
What changes in the binder
MC denotes medium curing, and the curing class is set entirely by the solvent, not by the bitumen. Rapid-curing grades are cut with naphtha-range material, slow-curing grades with gas oil or similar low-volatility distillate; medium-curing grades use a kerosene-class cut boiling roughly between 150آ°C and 300آ°C. Solvent is metered into the base binder in a closed blending vessel — of the order of 20–25% by volume for MC 800, against roughly 45–50% for MC 30 — with the bitumen cooled well below normal hot-storage temperature before injection, introduced below the liquid surface, and circulated rather than agitated in open air. Vapour control at this step is a process-safety requirement, not housekeeping.
Why it is not a paving grade
The distillation test, ASTM D402, distils a 200 mL sample to 360آ°C and records the volume recovered at 190, 225, 260 and 316آ°C. It answers two separate questions: how much binder is actually present, and how fast the solvent will leave. The residue minimum of 75% by volume is the binder yield you are buying. The intermediate figures, expressed as percentages of total distillate rather than of the sample, describe the volatility distribution of the solvent — and for a grade this heavy they are ceilings, not floors, because a heavy cutback must not carry a light solvent. In the field, the fraction off by 260آ°C governs initial set and traffic opening; the tail between 316آ°C and 360آ°C is what keeps a stockpile mix workable for months.
Cutback Bitumen MC 800 specification
Written against the governing standard rather than reproduced from a supplier datasheet, so every limit below can be checked against the published requirement.
| Property | Test method | Unit | Requirement |
|---|---|---|---|
| Kinematic viscosity @ 60 °C | ASTM D2170 | mm²/s | 800–1600 |
| Flash point, Tag open cup | ASTM D3143 | °C | min 66 |
| Water content | ASTM D95 | vol % | max 0.2 |
| Distillation to 360 °C — per cent of total distillate | |||
| to 225 °C | ASTM D402 | % | no requirement for this grade |
| to 260 °C | ASTM D402 | % | max 35 |
| to 316 °C | ASTM D402 | % | 45–80 |
| Residue from distillation to 360 °C | ASTM D402 | vol % | min 75 |
| Tests on the distillation residue | |||
| Absolute viscosity @ 60 °C | ASTM D2171 | poise | 300–1200 |
| or penetration @ 25 °C, 100 g, 5 s | ASTM D5 | dmm | 120–250 |
| Ductility @ 25 °C | ASTM D113 | cm | min 100 |
| Solubility in trichloroethylene | ASTM D2042 | wt % | min 99.0 |
Where Cutback Bitumen MC 800 is used
Cold-laid plant mix
Coats dense- or open-graded aggregate in a pugmill at ambient or slightly warmed temperature. The mix is hauled and laid cold, gaining strength over days as the kerosene evaporates, and serves base and binder courses on low-volume roads.
Mixed-in-place road mix
Sprayed onto aggregate windrowed on the carriageway and blended with a grader or travelling mixer. MC 800 suits coarser, more open gradings where a lighter grade would drain off the stone before mixing and aeration are complete.
Stockpile patching material
The heavy distillate tail leaves the mix workable in an open stockpile for several months, then allows it to stiffen once compacted into a pothole and exposed to air and traffic. A staple of winter maintenance depots.
Single-application surface treatment
Used as a chip seal binder in hot, dry conditions where MC 250 would bleed or run off camber. The higher viscosity holds the cover aggregate in position until most of the solvent has left the film.
Trench and utility reinstatement premix
Supplied to municipal crews as bagged or loose cold mix for small permanent repairs where hot mix cannot be delivered in workable quantity. Compacts under a plate compactor and cures in place over the following weeks.
Storage, heating and handling
Store in a dedicated tank; do not decant into a vessel still hot from penetration-grade service. Heat indirectly by steam or hot oil coil, never by direct flame on the shell, and circulate continuously so coil surfaces cannot crack solvent locally. Working temperatures for MC 800 sit close to, and can exceed, the 66آ°C minimum Tag open-cup flash point of ASTM D3143, so the tank vapour space must be treated as flammable at all times: exclude ignition sources, bond and earth during transfer, ventilate before entry, and avoid prolonged storage above roughly 70آ°C, which simply boils off solvent you have paid to ship.
Regulatory and safety context
Stated plainly, because a buyer who discovers this after purchase has a problem that content cannot fix.
Cutback bitumen is a deliberate VOC emitter: roughly a fifth to a quarter of every litre applied is designed to evaporate into the atmosphere. That is the whole reason it is regulated, and buyers should know it before they order rather than after. In the United States, state implementation plans built on EPA control techniques guidance for cutback asphalt restrict its use, most commonly by banning application during the summer ozone season and allowing only narrow exceptions such as stockpiled patching material or priming where an emulsion genuinely will not work. Western European practice has largely moved to bitumen emulsions; EN 15322 still covers cutback and fluxed bituminous binders, but specifying a solvent cutback against a current European job specification is now the exception rather than the norm. MC 800 nonetheless remains an ordinary, unrestricted trade item across large parts of Asia, Africa, the Middle East and Central Asia, and the correct question is not whether cutback is acceptable in general but whether it is acceptable at the destination. Separately, the kerosene fraction is an inhalation and skin-defatting hazard, hydrogen sulphide can accumulate in tank vapour space, and the flash point sits close enough to the 60آ°C dangerous-goods threshold that the closed-cup result on the actual batch — not the open-cup specification minimum — should determine the transport classification.
Available packing
| Packing | Net weight | Loading per 20 ft FCL | Typical use |
|---|---|---|---|
| New steel drum | 150 / 180 / 185 / 200 kg | 110 drums, 20.35 MT at 185 kg | Standard for this product class |
| Meltable or kraft bag | 25 / 50 kg | by pallet configuration | Oxidized blocks, direct kettle charging |
| Flexitank / bitutainer | 20–22 MT | 1 unit | Bulk economics without a vessel |
| Bulk vessel | by parcel | heated tanker | Terminal to terminal |
As a Cutback Bitumen MC 800 supplier Bitumen Asphaltive ships on CFR, CIF and FOB terms with commercial invoice, packing list, bill of lading, certificate of origin and certificate of analysis.
Questions about Cutback Bitumen MC 800
What does the 800 in MC 800 actually specify?
It is the lower limit of kinematic viscosity at 60آ°C in mmآ²/s, measured to ASTM D2170; the upper limit is twice that figure, so MC 800 runs 800–1600 mmآ²/s. It is not a penetration value, a temperature or a percentage of anything. The ASTM D2027 series — 30, 70, 250, 800, 3000 — steps roughly threefold at each rung, so adjacent grades are genuinely different materials rather than tolerance bands around one another.
Can MC 800 be used as a prime coat?
Not effectively. Priming depends on the binder soaking into an untreated granular base, and penetration into the surface falls sharply as viscosity rises. MC 30 and MC 70 carry close to half their volume as solvent and are fluid enough to wet and migrate downward; MC 800 carries roughly a fifth and tends to sit as a surface film that later peels or is picked up by construction traffic. If a specification calls for MC 800 as a prime, query it before ordering.
How long does MC 800 take to cure?
Days to weeks rather than hours, and the distillation curve predicts it better than any single number can. Curing here is evaporation, not chemical set, so it is governed by ambient temperature, wind, layer thickness and how open the aggregate grading is. The distillate fraction recovered by 260آ°C drives the early stiffening that permits traffic; the heavy tail recovered between 316آ°C and 360آ°C can persist for months, which is precisely what keeps stockpiled patching mixes workable through a winter.
Where is cutback bitumen restricted?
In most of the United States and much of Western Europe. US state implementation plans built on EPA control techniques guidance for cutback asphalt restrict its use, commonly prohibiting application during the summer ozone season and permitting only defined exceptions such as long-life stockpile patching. European practice has largely substituted bitumen emulsions, with fluxed binders using low-volatility or vegetable-derived fluxes where a fluid binder is unavoidable. Demand for MC 800 remains normal across much of Asia, Africa, the Middle East and Central Asia.
Is MC 800 shipped as dangerous goods?
It can be, and this should be settled before freight is booked. The specification sets a minimum Tag open-cup flash point of 66آ°C to ASTM D3143, but transport classification is based on closed-cup flash, which generally reads lower than open cup on the same sample. A batch sitting near the specification minimum can therefore approach the 60آ°C threshold that brings it under UN 1999, Class 3. Ask for the actual batch closed-cup result and the shipper’s written classification.
Related grades and overviews
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