Shoutout to the old timer who showed me his trick for cold joints on a big pour in Dallas

We had a huge slab pour for a warehouse floor last Tuesday, about 120 yards. The truck got stuck in traffic and we had a hard stop coming up on the first section. I was sure we were going to have a nasty cold joint right down the middle. This retired finisher, Frank, who was just visiting the site, saw me stressing. He told me to take my groover and cut a clean, straight line where the pour stopped, then brush the edge with a stiff wire brush and hit it with a light spray of a bonding agent from a garden sprayer. We did exactly that before the next truck arrived. When we poured against it, the new mix keyed in perfectly. No line, no weakness. I've done this on two pours since and it's saved my skin. Has anyone else used a method like this for planned stops?

2 comments

2 Comments

kareng2716d ago

Frank's trick works because you're making a clean mechanical key.

emery_miller2016d ago

My first cold joint looked like a bad scar across a driveway. I tried to hide it with a broom finish and just made it worse. Frank's trick is basically the opposite of my panic move.