One way of doing my little footing job would be to make five consecutive batches of concrete in a little electric mixer. I remember hearing someplace that if you don’t wash the mixer out completely between batches, the next one will harden at the same time as the first one. The idea is that the chemical reaction that’s starting in the residue spreads to the new stuff. I’m wondering if there’s any truth to that. Does anybody know? A truck and pumper seems like such overkill for just 5/8 of a yard.
Thanks —
— J.S.
Replies
John,
I mix consecutive batches of concrete in my mixer all the time. I've mixed up eight or ten batches of concrete in a row on many occasions. My mixer can handle three 80# bags of Quikcrete per batch. If the pour takes over an hour, you might want to stop and clean the mixer--especially if it's hot. An 80# bag of Quikcrete makes 2/3 of a cubic foot of concrete. So you need about 25 bags.
Hydration of portland cement begins when water is mixed in with the dry ingredients. The materials that were originally mixed with water will continue to hydrate (harden) but the remnants from one batch don't accelerate the hydration of freshly mixed materials. That's an old carpenter's legend.
Don't lend your mixer to anyone! They won't keep it clean.
Thanks! -- Hourly cleanings it will be.
-- J.S.
My very first job in construction in the summer of 1973 was mixing concrete in a mixer with the sand and gravel and portland stacked around me.I mixed all day,every day for three days.There were no redi mix trucks here in those days!You would have thought I would have learned my lesson right then and made plans to stay in school.Anyway,I rinsed the mixer at lunch break and the end of the day.The building the concrete went into is still standing straight,although I tend to lean some these days........what the heck was I thinking?
Just mixed 6 yards like this a few Saturdays ago. My method is to squirt a gallon or so of water into the mixer just after dumping into wheelbarrow, let it slosh while I empty the wheelbarrow from the previous load, then it's all set to go next load.
I just rinse the mixer when I'm done and clean it every few months with a 6# hand sledge.
I've also run my small mixer continuously for several hours. I mix a batch, dump it in the wheelbarrow, then toss the ingredients for the second batch into the mixer. While the second batch is mixing, I place the first batch that's in the wheelbarrow. After placing the first batch, the mixer is done with the second batch, so I dump that in the wheelbarrow...
It's non-stop and goes pretty quickly.
Unfortunately, I always seem to break before the mixer or the wheelbarrow breaks.
Ensure that you keep the mixer well lubed.
Edited 5/22/2002 12:58:54 AM ET by Mongo
I agree with John C. Go ahead and mix away.
Have fun,
Jeff