Is this an odd way of pouring a slab? or do others do this method..

nuzuki · 17 Apr 2020

Hi all,
I am working on a few interconnecting slabs presently all 2.4m by 2.4m and doing one every other day. I have found it easiest if I just load the mixer dry and then add the water until it overflows from the mixer into the concrete form. I never actually tilt/pour/lift the mixer once. It just slumps out and I rake it about. Kind of like an auto pour feature. Has anyone else used this method? It seems to work well and as a one man band doing this work it helps speed things up alot. A 2.4m by 2.4m 4inch slab takes me roughly 2hours.
Please share your comments, thanks

^woody^ · 17 Apr 2020

We had a Chinese labourer once , Lee Bruce, and he called this "the art of mixing without mixing"

We sacked him.

noseall · 17 Apr 2020

nuzuki said:
Hi all,
I am working on a few interconnecting slabs presently all 2.4m by 2.4m and doing one every other day. I have found it easiest if I just load the mixer dry and then add the water until it overflows from the mixer into the concrete form. I never actually tilt/pour/lift the mixer once. It just slumps out and I rake it about. Kind of like an auto pour feature. Has anyone else used this method? It seems to work well and as a one man band doing this work it helps speed things up alot. A 2.4m by 2.4m 4inch slab takes me roughly 2hours.
Please share your comments, thanks

I'd be interested to know how you gauge your mix. Good job you're not reliant on strength (me thinks this is a wind-up).

Alastairreid · 17 Apr 2020

What are the slabs for, they will be weak!

23vc · 17 Apr 2020

I’ve used the mixer off the stand and tipped and poured straight into the trench or whatever, and repeat. But your method sounds a bit mental, and sounds like it’d make a right mess of your mixer as half the mix pours down the outside of it.

John D v2.0 · 17 Apr 2020

if it were that good, everyone would be doing it!

nuzuki · 18 Apr 2020

Thanks for the replies. I do use it off the stand. The mix is strong as it's mixed dry and to the ratio needed. It's just when I add water it slumps out the mixer and kind of drip feeds the slab. I used 7 bags of cement in the 2.4m by 2.4m slab and just a little over 1 bulk bag of 850kg ballast. I was able to walk on the slab the next day OK.

Diver Fred · 18 Apr 2020

Do think your 'slabs' are on the thin side hence weak. Also casting in the way you have you will have movement and cracks between each slab. need some reinforcing in and between each slab.

StephenOak · 19 Apr 2020

nuzuki said:
The mix is strong as it's mixed dry and to the ratio needed.

I'm not a professional but, AFAIUI, when people are saying that it will be a weak mix they mean there is far too much water.

Concrete does not set by drying out but by a chemical reaction. The amount of water needed for the reaction to take place is very small, less than you need to make the concrete pourable.

Once the chemical reaction is complete [1] and the concrete is set, there will be excess water in the mix. This water will gradually evaporate leaving tiny cavities in the concrete. The more water, the more tiny cavities, the weaker the concrete.

1. By complete I mean a few days when it is solid and load-bearing. The reaction carries on for decades, but very slowly.

Notch7 · 19 Apr 2020

day joints are best avoided.....

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Is this an odd way of pouring a slab? or do others do this method..

nuzuki

^woody^

noseall

Alastairreid

23vc

John D v2.0

nuzuki

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Diver Fred

StephenOak

Notch7

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