What concrete mix for a ground anchor?

I bought a "ground anchor" for my garage and want install it using the strongest concrete mix possible.
I have bags and bags of Sand and small 'chippings', and hope to be able to use these.
I was told that I should use:
3 parts chippings 2 parts sand 1 parts cement
If this is the right recipie, should I use the chippings I have, or should I get the proper stuff.
Any info would be appreciated
Jon
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I'm no expert, but I would have thought ( I stand to be corrected ) that ballast containing a full gradation of sizes ( i.e. 3/4"-to-dust" ) would be your best bet. The usual recipe I have followed for concrete made with ballast is 5:1 ballast-to-cement by volume, so this looks the same as your recipe except for your having only two sizes of particle.
Note that wet sand does not settle, and the ratios are always given for dry sand, so make an allowance if you use wet sand ( I can't remember what it is! It's at least 10%, maybe 25% ).
The strongest mix of just sand and cement is 3:1, but I believe that concrete made with ballast is stronger than that made with just sand. It's all to do with the mixture where the spaces between the particles are maximally filled with cement particles. If the strength of cement is improved when using ballast rather than sand, it seems to follow that ballast containing all grades would be the strongest.
just my thoughts, theoretical rather than based on experience, though I'd be very surprised if anyone out there can quantify what strength you will gain over just using what you have, by using a different mix.
Andy.
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On 18 Dec 2003 14:38:48 -0800, snipped-for-privacy@alcatel.co.uk (Jon Weaver) wrote:

When I cleared my garage for my dad to use he went round to get my ground anchor out, it's still there. ;-)
Just used some readymix stuff to save hassle and added a bit more sand to bulk it up a bit. Been there three years so far and will probably still be there when the garage is long gone.
Mark S.
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snipped-for-privacy@alcatel.co.uk (Jon Weaver) wrote:
Hello Jon

That's Ok.

Dunno - what size are they? 10mm+ should be ok, but the nearer to 20mm it is the stronger the final mix will be. 3/4" was the old "standard" for most applications.
But... This isn't rocket science and as long as the basics are ok (you mix thoroughly, don't get it too wet and above all, keep everything clean!), you'll get a big heavy and solid lump of concrete that nobody's going to mess with.
IIRC, the best place is pavingexpert.com - lots of info there.
--
Simon Avery, Dartmoor, UK
uk.d-i-y FAQ: http://www.diyfaq.org.uk /
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