Watched a guy try to float a slab with a bone-dry mix yesterday

I was down at a job in Smyrna checking out a new subdivision and this kid is out there with his crew, mixing the concrete way too stiff. Like, you could see it crumbling at the edges instead of smoothing out. He kept adding more water after the fact (which you know is a no-go) and it just turned into a mess. I walked over and showed him how to test the slump before you even start, but honestly it took 20 minutes of rework. Has anyone else had to step in and fix a pour that was mixed wrong from the start?

3 comments

3 Comments

kim.zara25d ago

Bone-dry mix" is actually the right term for it, but not what you're describing here.

the_eric25d ago

Wait, are you saying people use that term wrong all the time? I feel like I've heard it thrown around for anything that's just slightly dry, and it drives me crazy too.

jade_johnson25d ago

I have to push back a little on kim.zara's comment. "Bone-dry mix" is not really the correct term for what you described. In the trade, "bone dry" usually refers to a mix that has almost no hydration water in it, like what you'd see in a really stiff roller-compacted concrete. What you're talking about is more of a "low slump" mix that's still workable if handled right, but the kid didn't know how to manage it. The problem wasn't the mix being bone dry, it was starting with too little water and then trying to add it back after the cement started hydrating. That's a classic rookie mistake that ruins the water-cement ratio.