As part of the never ending struggle to get the right solution for this
bloody slab I am now pricing and sizing concrete mixers.
[Although I am still actively considering ready mixed - especially given the
current weather forecast for the next week.]

Both HSS and Jewson seem to do similar mixers - a 'lightweight' 90 litre/.09
cubic metre electric or petrol mixer or a 'heavy duty' 110 litre/0.11 cubic
metre diesel.

Firstly, there doesn't seem to be much difference in the volumes.
Presumably the 'heavy duty' mixer just mixes a lot quicker.

Secondly, if the label on my barrow is correct then it holds 3 cubic feet
which is 0.085 cubic metres or 85 litres.
This seems remarkably similar to the volume of the mixers.

Given that I will probably not fill the barrow to the brim if the mix is
fairly fluid, this is still only about 1.5 barrows to the 'heavy duty' mixer
load.

In my mis-spent youth I worked for a time with a building firm as a labourer
and unless my brain is even worse than I thought we used to get more than a
barrow and a half from the mixers we used then.

Has the industry downsized the mixers in use or am I just getting
forgetfull?

I have vague memories of using a mix of 9 shovels of ballast to half a
(hundredweight) bag of cement.
However this would probably equate to a 110 litre mixer.
My spreadsheet suggests that a 110 litre mixer should take just over one
25kg bag of cement which suggests that 9 shovels and half a (50kg) bag would
give a mix slightly leaner than the C20 we were previously discussing.

So am I heading in roughly the right direction?

Bag of cement per mix, and producing 1.5 barrow loads of concrete?

Cheers

Dave R

Rather than the size of the mixer, I find it's more about what you can
gauge quickly and easily with the tools you have (and avoid mistakes),
and what you can comfortably move around.

My routine with a Belle Minimix (from HSS), is two trugs of ballast,
to one bucket of cement - giving me a 5:1 mix.

I use those proportions because of the neat ratio of bucket size to
trug size, that I can fill the trug with 5 shovels, and it's just
about at the weight I can comfortably lift and tip into the mixer -
and that it tips out into two barrowloads (but not too full that it
slops out).

And the moment I tip out the second barrowload, I tip in the next trug
of ballast to scour out the mixer. Then use the concrete in the
barrow, then come back and add the cement and a little water etc.

<(E-Mail Removed)> wrote in message
news:35674d55-d911-4812-9c7a-(E-Mail Removed)...
> Rather than the size of the mixer, I find it's more about what you can
> gauge quickly and easily with the tools you have (and avoid mistakes),
> and what you can comfortably move around.
>
> My routine with a Belle Minimix (from HSS), is two trugs of ballast,
> to one bucket of cement - giving me a 5:1 mix.
>
> I use those proportions because of the neat ratio of bucket size to
> trug size, that I can fill the trug with 5 shovels, and it's just
> about at the weight I can comfortably lift and tip into the mixer -
> and that it tips out into two barrowloads (but not too full that it
> slops out).
>
> And the moment I tip out the second barrowload, I tip in the next trug
> of ballast to scour out the mixer. Then use the concrete in the
> barrow, then come back and add the cement and a little water etc.

Useful information :-)
How much of a 25kg bag of cement goes into the bucket?

> How much of a 25kg bag of cement goes into the bucket?

Around half IIRC. though I don't pay it much attention.

I start off by tipping bucketfuls of ballast into the trug to remind
myself what the fill levels should look like, to get the ratio right.

Then it's just about refilling each as I use them - with no regard for
the ratio of cement bag to bucket.

On Feb 3, 4:36 am, "David WE Roberts" <nos...@talk21.com> wrote:
> As part of the never ending struggle to get the right solution for this
> bloody slab I am now pricing and sizing concrete mixers.

While you may be able to put a lot of mix in the bowl, you need a
motor big enough to turn the full bowl. I bought an el cheapo mixer
that could turn the dry mix OK but ground to a halt when I added
water.
Still it's OK for tiny jobs and I can wheel the mixer from the pile of
mix to the job, so don't need to transfer the concrete to a
wheelbarrow.