Calculating materials needed for concrete slab

Have you priced that up?
Compare it to premix £s. Just so much quicker.

 

A bag does 0.01 cubic metre ​

 

You are looking at around 1 cubic metre off all in one ballast plus maybe 15 bags of cement. Cost around £150 ish.

A bulk bag typically contains around 0.5 cubic metre.

Using ready mix bags - 100 of them at around £5-6 each, so £550

IN both cases you will have mixng time too. Be very sure of the depth, is it onto a firm base or into rough hardcore. Will you need a little more than 1m? you might if itis actually 80 or 85 mm.

Also, get some polyester fibres and add a handful to each mix.

 

I know it's nice to work hard and all, and there's a deep sense of satisfaction in calculating, mixing and laying the measured quantities out perfectly, but I would at least enquire with the local volumetric-mix it on site concrete suppliers how much they would charge for a cube, if it's in the region of £2-250 then I would bite their arm off and save all the faffing about.