Reducing the amount of concrete used by increasing aggregate?

dwoloz

For environmental and cost reasons, I'd like to minimize the amount of concrete poured for a small 12x10 footer/stem wall foundation I'm doing

I have lots of pieces of broken up old concrete available ranging in size (1/2 gravel all the way up to large chunks)

I have read that adding more aggregate would not affect the strength of the resulting concrete so long as the fines and cement could fully cover all pieces. True?

Tscarborough

Not true.

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LIHR

There is science behind the formula for concrete, and size and type of aggregate is a very important element of that formula. Do a quick search on proper aggregate for concrete.

If this was a non-critical mix such as a pad to place your garbage cans on I'd say go ahead and throw it all in, but being that it's not, I wouldn't reinvent the mix.

Tigerloose

And just how much are you going to save by mixing in chunks of busted concrete? Are you going to site mix or get the concrete delivered? You could save even more by substituting old bed frame rails for re-bar.

jomama45

I take it that part was a joke???


I wouldn't add any broken up concrete to the premix or ready mix and expect desired strength of the finished product.