Density of Sand

Measure it. Fine sand isn't a very precise term.

It actually depends on the sand and the supplier, as densities and properties can vary greatly - both in product and in application installation and usage.

I haven't heard of cable sand before (perhaps it goes under a different name down here).

Have you tried an internet search to narrow down a suitable local supplier and then a call to said local supplier for more information followed by an internet search of the characteristics of the sand types they supply to find something suitable?

2 g/cc.

You need to physically weight the sand with a known volume, then calculate it's density, because the unit weight of sand can vary greatly around any given region, not to mention the entire world.

You do know how to calculate a material's density, don't you? And don't forget to involve it's moisture content, if any.....

What does the Consultant/specifications say?.

pour one gallon of weighed sand in a calibrated container then pour one gallon of weighed water over the sand. the weight of the sand water mixture minus the weight of the water above the sand should give you a ratio of water to sand weight you can work with.

i hope a enginer chimes in. my answer is more complicated than it needs to be.