Crack Control and fiber addmixtures

[wlively]

Re: Crack Control and fiber addmixtures

I bought my stainless needles by the lb, less than $10.

[david s]

Re: Crack Control and fiber addmixtures

Thx1138 used some sisal rope fibers as reinforcing. That should work but don't know how it went. You could easily chop short lengths with a tomahawk, but make sure ou mix it in really well to distribute the fibers evenly.

[david s]

Re: Crack Control and fiber addmixtures

Yeah I use a few different fibers. First is the stainless steel needles for high temp application. They are not actually needles but more of a flat bar with ripples for grip and about 2mm wide by 40 mm long, although I guess there are other sizes. They don't present much problem in application. The only drawback is that you will probably have to buy way more than you need and stainless doesn't come cheap.
The second kind of fiber I use is a short and extremely fine polyproelene fiber that melts at 160 C This is no good for high temp stuff if you want it for reinforcing, but if used in high temp application the fibers burn away and leave minute pipes where the water can escape. This was developed as an addition to make concrete buildings fire proof. The third fibre i use is a longer plastic one that is used as a replacement to steel reinforcing in structural concrete. Our local council uses it for all the concrete footpaths and I use it for the outer concete shell. It is far simpler and quicker the chicken mesh over a spherical surface.

[MK1]

Re: Crack Control and fiber addmixtures

Stainless steel needles. $

Mark

[Fairview WFO]

I noticed the Pompeii instructions say you can add a layer of mortar to the outside of the dome to increase the thermal mass, for those so inclined. Has anyone done this with the addition of fiber reinforcement to that mix to aid in crack control? It certainly helps with concrete shinkage cracking and meets the temperature steel reinforcing requirements in those applications.

Scott