Concreting calculations

[Specialized29er]

Hi Guys, I'm looking to buy a 1/2 decent cement mixer instead of hiring one because at our new property I'd like a couple of 7 x 4m slabs and footings concreted and I'm trying to work out whether a 4 or an 8 cu ft mixer would do. Depending on the price compared to the amount of loads required with a couple of labourers helping.
I'm trying to convert 4cu ft to meters and have googled it and I keep getting 0.11 meters but 1/10 of a meter doesn't look right.
Would anyone know how to go about doing the conversion.

499750 $2,600 499751$470

[Picko]

0.1132672 cu m

[aldav]

1,000 (1 metre) / 304.8 (1 foot in mm) = ANSWER (1 metre expressed in feet)
ANSWER x ANSWER x ANSWER = a cubic metre in cubic feet
4 cf / a cubic metre in cubic feet = the proportion 4 cf is of a cubic metre

[Wrongwayfirst]

Yep you got it, it might not look right because one may list max fill level and the other mixer may list total volume.
A 200 litre drum = 44 gal so 1/2 of a 44 looks about right for a cement mixer

us gallon = 3.3 litres
uk (aus) gallon = 4.5 litres
1 cu ft = approx 28 litres = 6 aus gallons

28 x 4 = 112 = 0.11 cubic metres

cheers

[Bushmiller]

Specialized

In deciding the size to go for I am making an assumption that you will be tipping the concrete into a wheelbarrow. I had always worked on the assumption that a builders barrow held 5ft³ with some concreters barrows (they are longer and narrower ta aid in pouring) at 6ft³ . However a quick Google search indicates a builders barrow is between 85l (3ft³ and 120l ( 4.24ft³). 120l of concrete weighs close to 250Kg. Just some figures to toy with.

Your slab will require about three and a half tonnes of aggregate and around twenty five bags of cement (20Kg bags) and maybe 400l of water. The reason I know some of this is that I have just poured a slightly smaller slab for an oversize lawn locker at 7.6m x 2.3m. If you are doing it by yourself (not recommended) the smaller concrete mixer will be adequate! Be sure to start at first light. :)

499782

My mixer is very old, but will overflow a "builder's barrow." (larger size)

499783

There was a time when it could be towed on the road behind your vehicle, but I have never done that on the open road.

499785


Good luck with the pours. Young fit help is of the essence.

Regards
Paul

[Beardy]

I don’t if it is feasible to consider readymixed concrete in your location but it saves a lot of heartache and a better opportunity to get a consistent finish on the slab

[Specialized29er]

Thanks for the help guys and no the nearest readymix is 160klms away and the transport costs are crazy so while in the city yesterday I bought a Wel-Bilt 4 cubic foot mixer and got the Honda petrol motor one at a bargain price.