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I am planning to pour 40 square feet of 4" slab to support light shed. I was thinking of using 60LB bags of regular premixed concrete (not fast set). I figured that getting it as ready mix in a truck is way too expensive and also the site is 150+' away from the street.

What is the best way to do it so concrete wouldn't set before time and I don't kill myself? The place is very constrained so I can't fix electric mixer and it's tight even for wheelbarrow. My current plan is to use Leonard OdJob™ Concrete mixer and I will need abot 30 bags.

Any alternatives and hints?

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    I think you would be ok if you were mixing several bags at a time in a wheelbarrow, not so sure doing one bag at a time in that bucket thingy... seems like it would take all day. – Jimmy Fix-it Oct 15 '18 at 4:16
  • You could possibly add a concrete retarding admixture to slow the set time... – brhans Oct 15 '18 at 12:00
  • Looking at that mixer it has good reviews but looks to have the capability to hold 1 bag. 40 sq feet is not a very large pour but this will be be a lot of work, I have poured 12×12' 4" thick pads using a small 3 bag mixer, you might consider renting a small mixer , I know mine can go any place a wheel barrow can. You would not have the little mix can but in my area it would be cheaper to rent and a lot less work. – Ed Beal Oct 15 '18 at 13:56
  • In my area, there are 'mix on the spot' services that could produce 1/2 yard at the curb and give you (or some sucker, I mean helper) the chance to wheel it back to the slab in plenty of time to get a decent finish on. Two helpers/wheelbarrows would be even better. – Aloysius Defenestrate Oct 16 '18 at 0:49
  • The bucket is junk. Can't be used. I ended up mixing 1 bag at time in 27 gallon plastic box that I got in Costco. That worked ok with extra benefit that you can mix it by tilting it back and forth. – Uncle Meat Oct 25 '18 at 4:14
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The answer depends on your level of physical ability and ambition, and is therefore mostly subjective. There are plenty of folks who could do it. I wouldn't try it myself at my age and level of fitness. Concrete is really freaking heavy. I would want some additional labor on hand.

I attempted to finish a sidewalk and garage apron on my own when my help had to leave, and there's little as nerve-wracking as finding oneself racing the clock with setting concrete. You never end up with a good finish in those cases, and if you try something foolish like watering the mix you'll end up with a weak surface prone to flaking and disintegration.

My $.02: Play it safe and have someone around to help you mix and move the mud.

  • I agree for someone that is a rookie this could be a big job, although I see it as small wouldn't try it without a mixer (but used to wheel barrow mix as a young man) but it could be done. – Ed Beal Oct 15 '18 at 14:01
  • Even with a mixer, the thought of moving nearly a ton of concrete twice, and then finishing it gives me a shiver. – isherwood Oct 15 '18 at 14:02
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    I fully agree , I have 2 sons that live close they would be packing the bags, after 18 knee surgerys I don't do that much any more. – Ed Beal Oct 15 '18 at 16:08
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You want to pour a slab of 40 square feet (so something like 5 by 8) and four inches thick. Let's break it down with numbers:

I'm imagining about 1 bag per square foot, so you want approximately 40 bags (that might be a conservative estimate for 60-lb bags).
You mention a concrete-mixing device which you roll back and forth several feet in order to mix. I'm not convinced, but for now I'll just assume that that product works exactly as described on amazon: "fill it, roll it 10 feet, and then back 10 feet, and you have perfectly mixed concrete". Now, the TIME LIMIT here is crucial: sakrete says you can wait AT MOST somewhere between 20 minutes and 4 hours between pouring and troweling. So this depends on your climate &etc, but if I were you I would want to pour the 40th bucket of concrete within an hour of pouring the first bucket.

When you figure that you want all this mixing and pouring to take place within the space of an hour or so, and would want to run 40 bags through that mixer, that's about 1 minute per mix. I don't think you could keep up that pace even on the FIRST bag, probably more like 5 to 10 minutes per bag for a single person, right? (include time to lift that completed mix and pour it into place). In order to achieve that pace, you would want two people on the mixer and one running water and smoothing as you go.

  • I agree with your estimate. Their calculator tells 30 60lb bags for this area but still I think it may take 5 min per bag with this bucket. I was hoping for more time than 1 hour. At a moment, I think I will just split the job in two. I don't think it's critical for my project that it's single poured slab. Will just put board in the midle and pour and finish half one day and another half next day with some rebars between them. – Uncle Meat Oct 16 '18 at 6:52

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