andrewpreece wrote:

"Ian Stirling" wrote in message
...
andrewpreece wrote:

"Ian Stirling" wrote in message
...
With a given mix of aggregate and sand, is the strongest mix when
the cement paste fills the gaps between the touching aggregate, with
no extra?
Assuming that the mix does not have too much water?


Yes, I have seen this written somewhe the strongest mix is 3:1 sand
to
cement ( different for ballast of the 3/4" to dust variety ).

Hmm, so mixed sized gravel needing 300ml of water to fill every l of
gravel would reduce the amount of sand and cement by 3.

I used 8:3:1 of aggregate/sand/cement, mixed for a long time, it ended
up so that it would not easily flow, but would tamp down to a beautiful
firm surface.
Just wanted a sanity check, as others were doubting mine.

Given that the strongest mix is know to be 3:1 sand/cement, why don't you do
your little experiment with dry sand: if your theory is true, then dry sand
should absorb 1/3 of its own volume in water.

It does, about. (for the sand I've got)