This one.
Three parts sand
One part type ten portland cement
One third part fly ash, one third part condensed silica fume
Handful of glass fiber
Pinch of water reducer and liquid acrylic.
The water amount depends on how moist you sand is to begin with.

Thank you so very much tufaenough, that's it! Do you know where to buy the fly ash and silica fume?

I get my fly ash and silica fume from the big bulk plants.
But if you live close to the big city Rick Harmer can tell you where you can buy them retail.
If you have a bulk plant near by try them.

Thanks again tufaenough.

Rick I leave in Vancouver, do you know of any place around this area? any help will be greatly appreciated.

Sorry,didn't see your call for help until now.
For best supply help,I'd go first to TARGET Products in Burnaby.You're dealing direct with the plant,not a retailer.Second,Pacific West Systems Supply on Boundary in Burnaby(and bonus points if you come from the South along Boundary;it's nothing but trouble coming the other way!)
Universal for Davis Colours and superplasicizers,also in(wait for it!)Burnaby,near Brentwood Mall.You can e-me direct at rickharmer@hotmail.com if you have other questions about supplies.Until last year,we lived in Burnaby,but,we finally wised up and moved to the Sunshine Coast.Further from suppliers,but worth it for the space and piece of mind!
Cheers from a satisfied here!