ASTM C150 vs C595 cement

[Mike Mike]

What's the difference? I have a contractor requesting to use C595 instead of C150. Based on the 2 threads linked below, I gather that C595 has a lower carbon footprint, but we have less history/experience. My understanding is that Portland Cement C150 is a type of hydraulic cement and is often blended, and Blended Hydraulic Cement C595 includes Portland Cement. masonrygeek says "there are some nuances you should be aware of" and le99 shares an article that gives a brief overview of each "category" without telling us why there are 3 categories or what the differences are from the standpoint of a structural engineer/specifier. If the structural engineering community is expected to switch over to C595 I don't want to stand in the way of progress, but if anyone takes exception let them speak now or forever hold their peace.
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[JedClampett]

In my opinion, this is being rushed through. We're having problems with 28-day strengths and god knows what else. I think the research has not caught up, if there is any being performed.
The industry has over 100 years of experience with C150 cement and not even 10 years with 1L. I'm only afraid that our kids will being dealing with "nuances."