Vent: Discovered the hard way that poly fiber in mix causes cold joints

I tried adding polypropylene fibers to a driveway pour last month to cut down on cracking, but it actually made the concrete set way faster than I expected. Ended up with a cold joint right down the middle because I couldn't finish the second batch in time. Has anyone else run into this issue with fibers messing up your timing?

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the_thomas23h ago

A full driveway pour with poly fibers? That’s a bold move risking a 10-yard cold joint on a slab that size. I’ve seen fibers accelerate set time by up to 30 minutes if the mix is already hot or dry, which can wreck your whole schedule. Did you have a chance to slow it down with a retarder or ice in the water?