Tried a new mix design for a patio and the finish set way too fast

I was pouring a stamped patio for a friend in Mesa last month and decided to try a mix with a higher ratio of fly ash, about 25%, because I'd heard it could give a stronger, more durable finish. The day was hotter than expected, maybe 95 degrees, and I added a standard liquid retarder. But the whole thing just flashed on me in what felt like 20 minutes. I barely got the stamps down before it was too hard to texture properly. Had to grind off some high spots the next day, which was a huge pain. I learned that with fly ash, especially in the heat, you really need to adjust your timing and maybe use a different retarder. Has anyone else run into this with high-volume fly ash mixes? What's your go-to plan for hot days?

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hill.christopher6mo ago

Honestly... I've had the opposite happen. Used a 30% fly ash mix on a Phoenix driveway last summer, hotter than that, and it gave me more working time, not less. Maybe the problem was the specific brand of retarder... some just don't play nice with certain admixtures. Could have been a bad batch of cement, too.

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jennifersmith4mo ago

Dude, reminds me of a time I mixed in some leftover mortar just to see what happened.

7

patkelly6mo ago

Seen that exact thing with a bad batch of retarder...

1