Previously it was decided that the best approx 1" thick partition would be a 1" thick fibre cement panel, which would be very stiff and strong. Well, what I have decided to do is render-up a panel (vertically) to approx this thickness against a ply former and mesh etc. But I want the mix to be almost fibre-cement concrete, so it's very strong. What mix of cement, sharp sand, fibres and aggregate would be best to us ? The result should be very strong but also render-able without all aggregate sinking to the bottom etc. Cheers, Simon.
thin strong partition wall - followup
Jul 16, 2006
8 Replies
3:1 sand:cement, as this gives the strongest end result. Stronger mixes will microcrack during cure, thus weakening. 5% chopped alkali-resistance glass fibre will give you proper fibre reinforced cement. There are other fibre options too, but this is whats mostly used now that the asbestoses are out of fashion.
Will you use ss screws half way in top and bottom then the crete laid over them to fix it in place?
NT
Not sure what you mean about this last bit. I will be using mesh to render onto. I can see screws half way in for a mega-good key, but not sure what you mean by "top and bottom". Also, I wondered if putting in any larger aggregate than sand might help to make it a bit more like concrete ? Thanks, Simon.
Sorry, got it ! Screws in vertically to keep the entire panel in place. Cheers, Simon.
yes, as invisible fixings all along top and bottom. I dont know exactly how adding coarse aggregate would affect it.
NT
I'll do some experiments and post the results. Cheers, Simon.
Any idea where to get the glass fibre from ? Not having much luck on the web. Cheers, Simon.
Also, what about polypropylene fibres - these seem to be used in ready-mix fibre reinforced concrete ? Simon.
I looked into all this several years ago, dont know if I've got any links. Ah...
glass fibre in 1:1 mix for moulding:
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found a company supplying bundles of fibres for bridge building, only =A31-2 per bundle for 10 or 12mm poly.
Yes, I'd use them if I couldnt get any glass, but IIRC (and I might not) 5% glass will give a lot stronger end result, so is the choice fibre.
IIRC all fibres dont do the same thing. Poly acts primarily as crack control, and secondarily it increases the crete's tensile strength a few times. But this isnt the same thing as glass reinforced sheet, which needs a much higher tensile strength.
Its a while since I read up on all this tho.
NT
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