How much ballast sand cement do I need for a slab .. 3.2 x 4.2 @ 75 mm thick

3.2*4.2*0.075=1.008cube Depends on your ratio. One cube of sand is 1.5ton One cube of ballast is 1.75ton One cube of cement is 2ton If you do 4:2:1 you need Ballast 1.008/7*4=0.576cube 1750*0.576=1008Kg Sand 1.008/7*2=0.288cube 1500*0.288=432kg Cement 1.008/7=0.144cube 2000*0.144=288kg Always get abit extra incase. Sorry for the initial maths, it is Friday night.

Estimated cubic metres Based on the figures shown.it Is estimated that the following quantities shown on your question Required to complete your slab project will be approximately 1.008 cubic meters.

Speak to the relevant concrete division/ give dimensions and in return they will give you the cubic meters needed / ask you what strength you want the concrete/give you slump options on how much workability you need the concrete and if needed they can also offer you retardant shall you not want the concrete to set to quickly. Hope this helps