Old timer at a job site taught me a trick about water curing

I was working a big slab pour in Atlanta last August, this guy named Walt who had to be 65 watched me hose down the concrete. He told me to use wet burlap and keep it on for 7 days instead of just spraying it. Said the water evaporates too fast in the heat and you get surface cracks. I did it his way on that job and had zero cracking. Any of you guys use burlap for longer cures or is it just an old school thing?

2 comments

2 Comments

blair_lewis851d agoTop Commenter

Walt sounds like the kind of guy who's forgotten more about concrete than most people will ever know. Burlap trick is solid though, I've seen guys spray water on a slab all day and still end up with a spiderweb of cracks because the sun just sucks it right out. The old school methods usually stick around for a reason, even if they look like something your grandpa would do in his workshop. Glad you got a clean pour out of it, nothing worse than watching your hard work turn into a puzzle.

grant_cooper1d agoMost Upvoted

I read this thing once about how the Egyptians used wet burlap to keep their mud bricks from cracking in the sun, so that trick is literally thousands of years old. People think new technology always beats old methods, but the sun hasn't changed and concrete still dries the same way it did back then. Water evaporates fast on a hot day and pulling moisture out of the surface too quick is what causes all those little hairline cracks. The burlap holds the water right where it needs to be instead of just running off or steaming away into nothing. It sounds too simple to work but that's usually how it goes with the stuff that's been around forever.