Commodity Trading
Reading a rebar mill test certificate before you pay
The mill test certificate is the only document that tells you what is inside a bundle of steel. Here is what to check, line by line, before the documents go to the bank.
Commodity Trading
Bitumen for Gulf heat: penetration, viscosity and performance grades
A road surface in Muscat in August sits above 60 °C. The grade of bitumen in the contract decides whether it ruts in the first summer or lasts for years.
Bitumen is sold under several grading systems, and buyers often receive offers in one system for a tender written in another. Knowing how they relate saves rejected cargoes and awkward conversations with road authorities.
Three ways to grade the same product
- Penetration grades such as 40/50, 60/70 and 80/100 measure how far a standard needle sinks into the bitumen at 25 °C. Lower numbers mean harder bitumen. Grade 60/70 is the workhorse of road building in the Gulf.
- Viscosity grades such as VG-30 and VG-40 measure flow at 60 °C, closer to the temperature of a road in summer. They are common in South Asian tenders.
- Performance grades such as PG 76-10 describe the range of pavement temperatures the binder is designed for. Heavy-traffic roads in hot climates often specify polymer-modified binders graded this way.
Tests that belong on the certificate
A certificate of analysis for paving bitumen should report penetration, softening point by the ring and ball method, ductility, flash point, solubility and the change after a thin-film oven test, which shows how the binder ages during mixing. For performance grades, ask for the full set of rheology results, not only the grade name.
Packing changes the price and the risk
Bulk bitumen travels hot, in heated tankers or bitumen carriers, and needs heated storage at the destination. Where that infrastructure does not exist, bitumen is supplied in steel drums or in one-tonne bitubags, polypropylene bags in which the bitumen sets solid and is melted again at the plant. Drums are heavier and leave waste; bags are lighter and cheaper to ship but must be stored out of direct sun.
Matching the offer to the tender
Before accepting an offer, translate it into the grading system of the tender and confirm each test limit. A 60/70 offer may or may not meet a VG-30 requirement; the softening point and viscosity decide. Our bitumen desk supplies penetration, viscosity and polymer-modified grades from refineries in the region and checks the certificate against the tender before loading.
