sm_jamieson wrote:
sm_jamieson wrote:
wrote:

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.

Any idea where to get the glass fibre from ? Not having much luck on
the web.
Cheers,
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:
http://www.cem-fil.com/cf_grc_manufacturing.html

List of articles
http://www.tfhrc.gov/structur/concrete/subj4.htm
http://en.wikipedia.org/wiki/Reinforced_concrete
http://www.pavingexpert.com/reinfrc1.htm

I found a company supplying bundles of fibres for bridge building, only
£1-2 per bundle for 10 or 12mm poly.


Also, what about polypropylene fibres - these seem to be used in
ready-mix fibre reinforced concrete ?
Simon.

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