Old timer at the batch plant taught me about slump

Guy named Chuck, must have been 70, saw me loading up at the plant in Phoenix. He pointed at my mix and said ‘that’s gonna be a dog to finish.’ Asked how he knew. He tapped the drum and said he could hear the water was off by 2 gallons. Been listening to my loads ever since. Anyone else got a weird trick for checking slump on site?

2 comments

2 Comments

simon_davis18d ago

You ever notice how the really good guys can just look at a load and know? I had a foreman back in the day who would grab a handful of mix and squeeze it, then just nod or shake his head. Took me a while to figure out what he was feeling for, but he was almost always right about whether the slump was in range. Chuck's trick with listening makes sense too, you can hear the water sloshing different versus a drier mix rumbling around in there. The key is you gotta get your ear calibrated against the actual slump test results until you can trust what you're sensing.

skyler_craig18d ago

You ever try timing the drum revolutions after the water's in? Chuck's ear trick is solid, but you can hear the mix change pitch after about 15-20 revs. A wet load will start slapping around faster, a dry one will keep that hollow thumping sound for longer. I've been counting revs on my phone for the last year and it lines up with the slump cone better than guessing off sound alone.