I intend to pour a slab where my deck steps will land. The dimensions are
approximately 80"x24"x6" (LxWxD) or roughly 6-2/3 cubic feet. The ready-mix
plants in town won't take an order for anything less then 2 cubic yards, so
I'm left to mix Quikcrete in my wheelbarrow. I'm thinking mixing 20 40#
bags of Quikrete is going to be a huge chore, so I'm wondering if I can
break up an existing concrete slab (the wife decided she wanted the steps
somewhere else) and use that as filler material -- not to save money but
rather to cut down on the amount of mixing I will have to do. Is this a
stupid thing to do? Would it considerably weaken the slab? If not, what
would your filler-to-mix ratio be? Thanks for any advice.

Dale

"DRM" wrote in message
news:qJ8Je.243669$xm3.94859@attbi_s21...

I intend to pour a slab where my deck steps will land. The dimensions are
approximately 80"x24"x6" (LxWxD) or roughly 6-2/3 cubic feet. The
ready-mix plants in town won't take an order for anything less then 2
cubic yards, so I'm left to mix Quikcrete in my wheelbarrow. I'm thinking
mixing 20 40# bags of Quikrete is going to be a huge chore, so I'm
wondering if I can break up an existing concrete slab (the wife decided
she wanted the steps somewhere else) and use that as filler material --
not to save money but rather to cut down on the amount of mixing I will
have to do. Is this a stupid thing to do? Would it considerably weaken
the slab? If not, what would your filler-to-mix ratio be? Thanks for any
advice.

Dale



Why not just order the 2 yards of ready mix. They take back what you don't
use..your close to 1 yard as it is, it's simply a minimum order, they do not
require you to accept the full order, they never do. So what if you pay for
the extra yard, well worth it with the time you'll save plus all the back
breaking labor it would be to mix 20 bags!

-Brian

I'm wondering if I can
break up an existing concrete slab (the wife decided she wanted the steps
somewhere else) and use that as filler material --

I have seen "natives" break up concrete slabs just to use the pieces as
aggregate. No reason you can't do the same. If you combine the extra
aggregate with a bag mix, you might add some additional pure Portland cement
to the mix to keep the mix workable without reducing the strength. (The
strength is mostly a function of the water/cement ratio. If you add water
to keep the mix workable and don't add extra cement you end up with a weak
mix.)

If you don't want to break up the pieces to "aggregate" size, you can get
some mortar mix and put them back together as a "rubble wall."