Author Options:

how much concrete do i need? Answered

ok folks im building a bushfire bunker and i need to know how much concrete i need to make 4 walls 10cm thick 2m high and 4m long what kind of concrete i need and what kind of mix it should be how i should mix it etc i have had almost no prior experiance concreting so any tips would be appreciated



Best Answer 7 years ago

4* (0.1*2*4) = 3.2m^3 of concrete

Cheers can you go into detail about what that actually means eg how much concrete I need to buy cheers

You need to order 3.2 cubic metrees of concrete.

I'd strongly recommend that you contact whoever runs forest fire/brushfire crews in your area and ask them what's standard for this purpose -- as well as asking them exactly what designs are recommended. If you get it wrong, you'll have designed an oven. Which may or may not be an improvement over just clearing a patch of ground and covering yourself with a fire blanket.

(Excellent song describing the hazards of fighting wildfire, and the invention of what is now (I believe) a fairly standard escape technique: _Cold_Missouri_Waters_, by James Keelaghan)

I know this is old, but if anyone comes across it we do have a concrete calculator on our website. Should make figuring out questions like this much easier. 

I'd build an earth shelter rather than all the concrete anyway.

Not trying to slam you, and I am not an expert in these matters... but this sounds like something that you may want to leave to others. Calculation and mixing the concrete is very likely to be the easiest part of the job. Selecting and placing reinforcement, constructing the forms to hold the concrete, bracing the forms and removing them afterward, all can be pretty challenging for the first-time worker.

Having myself mixed a few hundred pounds of concrete by hand, I'd go with "ready-mix" (that's the usual US term) when possible.  It means that the truck comes to your location, mixing the concrete along the way, and the truck pours the concrete into your forms.  It's been about 10 years but I paid $45 per cubic yard---delivered---for about 13 cu. yd. of concrete. (Sorry, we don't have logical measurement units in the US, but one cu. yd. is roughly one cubic meter.) :-)

Good luck!