Lowes has 50 pound bags on sale for $1.79. The sale ends 7/1. I had a 5x12' x 1' deep concrete slab we hammered out that was about 2 ft higher than the floor and I'm going to pour a new slab to level the floor. Would the bags be ok outside under a shed for a day or two?

I plan on getting a full pallet full, which is 70 bags. I won't need but around 50, but on the other side of my shop I am leveling the floor up and will use the left over to do that.

Also, would it be worth the investment to buy a concrete mixer ($279) from lowes, or do it by hand?

Yup, no problem.  Even after several humid nights the 10 bags I had under my back porch were fine.

that's 2.2 yards of concrete forget about mixing it by hand you will end up with cold joints and it will look and preform like crap. Order 2.5 yards from the concrete plant and have it delivered.

Roughly the same cost as well after factoring in a mixer rental.

 

Cant its inside my shop in the basement no access. Plus concrete companys minimum load is 5 yards. It will have tile over it anyway

Until it rains.

It'll be fine as long as it doesn't get soaked.

And by the mixer.  When your done you will have a kickass brass tumbler.

Ok so my stubborn fiance insists on doing the concrete by hand. We're talking around 55 bags for the slab. How long will it take to do it by hand in a 4 cu. yd wheel barrow?

Way to long you are going to end up with cold joints where concrete joints wont join good with each other because it will  start to dry out and then you have to have time to work the concrete for a level smooth slab. I suggest your forget the bagged concrete and order it from the plant after all its 2 yards. If you are have a hard time seeing what two yards looks like imagine a box 3' x3' x 3' full to the top and that will be one yard. If their is no access to the basement from the outside I suggest you find someone with a pump and run a hose down there. I make this suggestion as someone who has poured thousands upon thousands of yard of concrete in everything from house footers to bridge decks and footers to multi story building slabs footers and floors and walls.

You can do it.
I've mixed 4 palletts of quik crete with hoe and wheelbarrow.
Usually 20-30 bags per section then pull the forms the next day and do another 20-30 bag section.
You will need help, usually 3 total minumum or 4 is best.
Someone mixing concrete continually using 2-3 heavy duty Jackson wheelbarrows,
Someone running wheelbarrows, someone smoothing/shaking the concrete out.
And one guy to help here and there(run the water hose, help mix or run wheely)
Good luck finding help that will work.

This, it's doable, but not very much fun.



If it's in a basement, you don't always have to pump it in.  In the past, we've built chutes through a basement window to get the mix down.  Wheelbarrow outside dumps onto chute which dumps into a bucket or wheelbarrow in the basement.  Pump is easier, cleaner, and more convenient but the chute is cheaper and works nearly as well ignoring labor.



The key that's being pointed out by others, you can't expect a good finished product if you don't have the help to have a continuous supply of mixed concrete.  If you have to keep stopping to make a new batch, the early stuff will begin to set up and you'll end up with cold joints and/or poor finishes on top.



 

Also, call around to the concrete plants.  They often have different minimums.



You MAY also be able to work a deal if they have a pour nearby that could load a bit extra on the truck and hit you on the way back to the plant.  I wouldn't hold your breath waiting on that to happen, but we've worked it out that way before.  Of course we do a lot of business with these plants and that may have some bearing on it.

They would be doing that by themselves.....