# Concrete mix for strongest cylinder?



## cleveman (Dec 28, 2007)

What does "gradation" mean? I assume that you get large rocks, then 1/4" or 1/2" smaller all the way down to 1/4" or 1/2" rocks? I have always heard that you want to have big chunks separated by smaller chunks, which are separated by even smaller chunks separated by sand, all held together by the "glue".

I don't think the concrete companies are going to keep 3" rock around for 8" poured walls however. It seems like the largest rock I'll find is in the neighborhood of 1 1/2". But the "gradation" seems to be there insofar as there are plenty of smaller rocks in there as well.

So to make it simple, I suppose you get a pile of 1 1/2", 1", 3/4", 1/2", and 1/4" rock and take a shovelful of each one until your "aggregate" measuring cup is full.

Righto or wrongo?


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