These AR Fibers OK?

[WaterDog]

Found these online that seem to be what’s required for Castable reinforcement $11/lb

Alkali Resistant Glass Fiber Reinforced Concrete
Fibers for concrete cement countertops, AR Glass Fiber GFRC Chopped Strands 1 LB
PH901X AR Glass Fibers is the heaviest strands of the of the leading fibers manufacturer Nippon Electric Glass America Inc. PH901X Fiber Strand contains 200 filaments. 18 microns diameter of the filament provides your GFRC with the highest integrity and the most resistance to filamentization during mixing and processing. 19% or higher zirconia content provides excellent fiber alkali resistance and acid resistance. Suitable for spray-premix Perfect for mortar and concrete reinforcement applications; all decorative applications as countertops, fireplace surrounds. Manufactured by NEG America Inc., Japan in compliance with ASTM C1666/C 1666M, EN 15422 and under recommendations of PCI and GRCA

They do appear as more of a chopped fiber (see image) but I assume they will break apart somewhat during mixing. They're available in 13, 19 or 25mm lengths. I’m planning on using these as my main reinforcement for my oven (no needles).

Are these correct?

If so, what length is preferred?

[david s]

They look like the correct ones. As you’ve found, they are expensive. Be careful of cheaper Chinese ones sourced from the net. I’ve heard stories about very low zirconium coated ones which could fail. I get mine from two different sources, both are 19mm long and very nice to work with, in that they’re no trouble to handle either dry or in the wet mix and they disperse readily.

[WaterDog]

Thank you, David!