What ASTM C989 covers, and what it does not

ASTM C989/C989M is the standard specification for slag cement for use in concrete and mortars. The material it describes is finely ground granulated blast-furnace slag. Grades 80, 100, and 120 are defined from the slag activity index, a strength comparison against portland cement at specified ages. The document also sets chemical and physical requirements for that ground product, including sulfur species and fineness.

Read the scope before you paste the designation into a raw-materials contract. The standard is about slag cement. Raw GBFS has not been ground to cement fineness and has not been tested as a finished cementitious powder. A cargo of granules is not “C989 Grade 100” because someone hopes the mill will get there. The grade is a result on the powder, after grinding, under the test method the standard names.

That does not make the standard irrelevant to a raw purchase. A grinder buys feedstock because the finished powder has to meet C989, or a project specification that points at it, or a blended-cement standard such as ASTM C595. The raw contract should protect that path: chemistry and glass that give the mill a chance, moisture the dryer can live with, and a rejection rule both sides understand. The raw contract should not pretend the granule already carries the finished grade.

ACI 233R is the committee report people use when they want a plain discussion of slag cement in concrete. It is guidance for use of the ground material. It is not a certificate, and it is not a GulfGran listing.

GulfGran does not claim ASTM certification, a listing as a slag-cement producer, or approval by a state transportation agency. If a mill holds those, they belong on that mill’s paperwork. When we coordinate a GBFS supply, we will say which documents are in hand and which tests have not been run. Inventing a grade to sound complete is how a first cargo becomes a dispute.

If your laboratory needs the current text of the standard, buy it from ASTM rather than relying on a paraphrase. This note is only a boundary: C989 follows grinding. The GBFS page repeats that boundary next to the product, because it is the sentence most often lost in a commercial email.