I was dead set against using fiber mesh in my mix until a job in Phoenix last July

I always figured fiber mesh was just a gimmick to sell more bags of stuff. But we had a big 4,000 square foot driveway job in Phoenix last July and the temps were hitting 112 every day. The foreman insisted we add it to control shrinkage cracking since we couldn't keep the surface wet long enough. I figured I'd prove it was useless, but after 6 months not a single hairline crack showed up on a slab that would have had at least a dozen in normal conditions. I'm still not buying every additive they push, but that one earned some respect from me. Has anyone else had a job where a certain additive actually saved your butt more than the usual methods?

3 comments

3 Comments

the_oliver1d ago

Man, that's a solid testimonial right there. I've seen fiber mesh save a few jobs in the heat too, but only when you really need it. Still think it's overkill for most pours though.

jenny_lee1d ago

That 4,000 square foot driveway in Phoenix heat is exactly the kind of scenario where fiber mesh pulls its weight, especially on the edges where the sun hits first and hardest. I saw a crew try it on a 3,000 square foot warehouse floor in Tucson last August, and the difference between the sections with and without it was night and day after the first year. It's not a cure-all, but for big flatwork in extreme heat it's one of those things you just have to admit actually works.

ray_sullivan1d ago

Look I get why people like it but I still think fiber mesh is one of those things that sounds better on paper than it works in real life. Yeah it helps with plastic shrinkage cracking during the first few hours but it does absolutely nothing for structural cracking when the ground settles or shifts. You still need rebar or wire mesh for that and the fibers can actually make the concrete harder to finish smooth which leads to other problems down the line. Also seen plenty of fiber mesh jobs where the fibers start poking out on the surface after a couple years of weathering which looks terrible and can even be a safety hazard if kids or pets are walking barefoot on it. Maybe I'm old school but I'd rather spend the money on proper control joints and a good mix design with low water content instead of betting on a bag of plastic straws.