Saw a stat about fly ash that blew my mind

I was reading a concrete report online, just killing time, and found out that using fly ash can cut the carbon footprint of a mix by about 25%. That really surprised me because I always thought it was just a cheap filler, not a big environmental thing. I've been pouring slabs with 20% fly ash for years on jobs in Cleveland and never knew it mattered that much. Has anyone else looked into these numbers and changed how they talk to customers about mixes?

1 comments

1 Comment

the_thomas12d ago

My batch plant in Columbus switched to 30% fly ash last year to hit a LEED target, and we saw the strength gain slow down by two days in cold weather. That 25% number probably comes from a lab mix with ideal curing, not a real job site in Ohio in March. I've had customers push back on the gray color and the delayed set, and honestly, the carbon savings don't mean much to them when the slab is still soft on day three. The report you saw might be using a baseline that's already high in cement, so the cut looks bigger than it is on a normal mix. I'd rather stick with 15 to 20% and be honest about the trade-offs than sell a green story that doesn't hold up on site.