How many sacks of cement do I need?

There's lots of calulators here.

 

I would reckon a sith load of ballast and a bucket load of cement.
Seriously, ask your builder or even your supplier.
5m x 3m at 25cm deep may need reinforcing depending on what it is for.

 

25 cm of concrete thats quite thick are you sure you have that right ?

 

thin for a multi storey car park ;-)

 

Are you building a shed for FatHands?

Mr. HandyAndy - Really

 

25cm that 10" in old money, what are you putting on it or is it a stand for you're wallet!

 

If its only pedestrian traffic, then 100mm with one layer of 142 mesh set at 50mm will be more than enough, but if it by a pool area for sun loungers why not use paving slabs, would look much nicer.

Cement is normally in 25kg bags.

 

100mm should be more than ample, so about 1.5 cubic metres, so just over 2.5 tons to mix.

I look at ready mix.

 

That's funny that in France cements in 35kg bags, ours used to be 50kg, but dropped to 25kg because of European health snd safety laws, seems like Franch is ignoring EU law again.

Seriously you could get away with 75mm with a 100mm toe around the edge 300mm wide and reinforcing, as long as you use a vibrating poker to remove all the air from it.

Forget all the writing on this pic, it just to show what i mean by a toe.

 

Doing that would depend on soil conditions & sub base.

Those were the day Phil, & 50kg cement & plaster bags, youngsters would run a mile if we had them today, my 18 year year old nephew complained about weight of a 25kg of plaster & having to lift it.

 

Youngsters of today don't know their born, used to carry one bag on each shoulder, 100kg, little darling today would die at the thought.

 

I use to able to do that 35 years ago,but struggle now to carry 25kg, knees,back,etc, wearing out.

 

Probably from carrying 100Kg when younger.

 

No, mc accident, plus being knocked down end of 2014 by a car, hoping to have op in a few weeks to sort shoulder.

 

Yep as a 15 year old used to lug those bags around and then sometimes double working nights in a bakery and sometimes had to unload the delivery lorries which had even heavier bags of mix the size of tackle bags.

Well before gym's were fashionable it was excellent training for rugby

 

Yes compact some hard-core down first, if the ground is good and solid 50mm will be plenty.

Don't forget to put a membrane down first this will help spead the load and stop any damp coming up through the slab