On Thursday, June 8, 2017 at 5:51:17 PM UTC+1, Al-W wrote:
It looks like a reasonably full jumbo bag from a decent builder's merchant.
I'm thinking of a 5:1 mix of ballast to cement. Anyone know how much cement I need for the whole jumbo bag of ballast?

PS The jumbo bag is of standard size, and is filled so that I can just manage to cover its contents by folding the upper walls of it over and inwards.

Al