Why I stopped using plastic fibers in my concrete mix

I used to always throw in a handful of those synthetic micro fibers for crack control, thinking it was the only way. Then a job at a school parking lot in Austin back in 2022 had the surface checking like crazy after two weeks. Has anyone else seen worse results with fibers compared to just good wire mesh and proper joints?

2 comments

2 Comments

sarah_brown6d ago

Used to swear by those fibers myself until a warehouse floor I did had worse spiderwebbing than anything I'd ever poured with just mesh. Saw a materials guy from TxDOT explain how the fibers can actually trap water and cause surface issues if you don't vibrate the mix just right. Really made me question the whole shortcut approach and go back to old school methods for flatwork.

caseyl186d ago

Wait, so you're saying the fibers actually make things worse if you're not careful? Man, I used to be all about throwing fibers in every slab I poured, thought I was being smart skipping the mesh. But I've seen what you're talking about now, those little hairs poking up everywhere, that spiderweb cracking is a nightmare to explain to a customer. It's like you think you're saving time and money but then you're out there patching and grinding for days. That TxDOT guy makes a lot of sense too, never thought about water getting trapped like that, it's probably why some of my older jobs had those weird blotchy spots. You got me rethinking my whole approach for flatwork now, maybe the old ways are the good ways for a reason.