Type IL cement (portland-limestone cement)
A blended cement that replaces part of the manufactured clinker with finely ground limestone. It performs comparably to ordinary portland cement while cutting the carbon footprint of each pound.
What does type il cement (portland-limestone cement) mean?
Type IL has quietly become the default cement across much of the United States as producers converted their plants, often without contractors noticing a change in the concrete they ordered. The limestone is ground in at the plant rather than added at the batcher, so it is part of the cement itself. Finished performance is designed to match conventional portland cement, though crews sometimes report slightly different set and finish behavior in cold weather.
In practice
If your supplier's mixes changed designation from Type I/II to Type IL and your crew swears the concrete 'finishes different' in November, this is the reason.