How much dust and sand....

TBH and IMO in that application, it's not critical. It's not as though you're building a ten story block of flats that might fall down if the wrong mix was used. All you're doing is supporting some edging strips to a patio, but I would avoid using too coarse an aggregate. If it were me, I'd use 1 part cement to 5 parts gritty sand, and it would be perfectly OK. KISS!

I don't think there is quite enough information here. Does the OP want a raised edge, or is he setting it flush to the patio. What's the construction of the patio, and what load might it bear? If he is after "raised edges", then how high, and might they see impact from (for example) small (or larger) children on bicycles, etc.

Mmm. 1:5 cement to sharp sand is a bit too weak for me. 1:3 or 1:4 (by volume) and a bit of lime instead of some of the cement works quite well too.

I always use white rather than grey cement too.

Looks better.

Work out what volume of concrete you require (will depend on the depth of your trench etc).

The use this calculator for the right quantities.

There is a complete guide to block paving including how to do edging courses here:

and in particular:

Yup that should be fine.

You can use sharp sand. Concrete is a mix of coarse aggregate and sand... you can with buy gravel + sand + cement or in some places you can get what is often called "all in one ballast", which is a mix of gravel and sand, so you just need to add concrete. (note that geographical names for these things change a bit - in some places "ballast" will refer to just a coarse gravel)

Note when using all in one ballast the quantities are not the same as just the total of gravel + that of sand (since 4 m^3 of gravel and 2m^3 of sand mixed does not give you 6m^3 of final stuff (the smaller sand fills in the gaps between the larger bits of gravel)

Oh dear

No, concrete is a mixture of coarse aggregate, sand, and *cement* and, of course, water. And sometimes steel.

you can with buy gravel + sand + cement or in some places you

No, you just need to add CEMENT. And its not called 'ballast'. Its called 'aggregate', or more specifically 'composite aggregate' with sand in it.

Which is what it is.

Ballast is a railway term.

In message , The Natural Philosopher writes

Unless it has been used to get an empty ship safely home:-)

Yes sweetie?

Well thank you for the subtitles for the hard of thinking...

That would be reinforced concrete...

Indeed mea culpa

Round these parts its very much called ballast or all in one ballast.

You may find it different in yokel land...

Sometimes.

or an electrical, or shipping, or dead weights in a news group.