Phil L wrote:
Peter Lynch wrote:

I'm planning on laying a concrete slab. In an attempt to stop it
cracking I'm considering adding fibres to it. Now, it'll only be a
couple of m3 of concrete, so I reckon I'll only need about 1kg of
fibre. Anyone know where I can buy some in this quantity?

Pete

1kg of fibre for a couple of cubic metres of concrete? - this is a waste of
time and money...unless you meant a couple of square metres of concrete
(m2)?

If you did mean square metres, then you don't need fibre anyway, so long as
the concrete is at least 100mm thick.

1kg per 5000kg, you'd want a lot more than 1kg. 1% is 50kg. Fibre
greatly reduces cracking by increasing tensile strength and controlling
any cracking that occurs, so if you've got easy access to it its worth
using for longer life and much less cracking risk. Also means thinner
crete wll work satisfactorily.

The cheapest source of fibre is probably scrap 100% synthetic clothes
shredded. I dont remember what company I, it was a while ago. Since
then I just made my own from junk. Its used primarily in bridge
building, so perhaps search terms like nylon polypropylene fibre
reinforcement bridge might work.


NT