Fiber reinforced concrete slabs on grade
Fiber reinforced concrete slabs on grade
(OP)
Hello,
I'm sure this has been discussed to death but needed to ask your opinions about fiber. I work for a building supplier but have been a SE for 30 years and this topic keeps coming up. Will macrosynthetic fibers adequately replace regular rebar in slabs on grade?
I know it will it help for crack control but is there anything else I need to be concerned about? Namely, the building we are erecting onsite at our facility will have forklift traffic on it and the occasional semi backed into the building. The concrete guy wants to replace the #4 @ 18" o.c. that I've called out for this 6" slab with the synthetics per the report attached. I'm also concerned about the hairpins I have in the slab, will the synthetics adequately transfer that load?
Thanks,
Dwayne
I'm sure this has been discussed to death but needed to ask your opinions about fiber. I work for a building supplier but have been a SE for 30 years and this topic keeps coming up. Will macrosynthetic fibers adequately replace regular rebar in slabs on grade?
I know it will it help for crack control but is there anything else I need to be concerned about? Namely, the building we are erecting onsite at our facility will have forklift traffic on it and the occasional semi backed into the building. The concrete guy wants to replace the #4 @ 18" o.c. that I've called out for this 6" slab with the synthetics per the report attached. I'm also concerned about the hairpins I have in the slab, will the synthetics adequately transfer that load?
Thanks,
Dwayne






RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Fiber reinforced concrete slabs on grade
The focus of the research and testing was to use fiber as an enhancement for the concrete mix. Its primary purpose was to control either "first crack" considerations and/or long term shrinkage cracking.
I have done research using fibers in concrete and asphalt....both for similar reasons.
The intent was never to replace rebar....it was and still is only a mix enhancement that increases the mechanical properties of a concrete mix, including compressive, shear and tensile strength....but never enough to delete rebar.
RE: Fiber reinforced concrete slabs on grade
I also was taught, and practice, that fibers are for micro crack control. If you are a slab on grade, and it can support the load as plain concrete then your rebar is not needed. If you are a PEMB, and the slab is used to resist thrust, then you will still need a way to handle that load. it appears that #4 @ 18 is just the recommended shrinkage area (almost .002 Ac)...
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
Mike McCann, PE, SE (WA)
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
https://www.youtube.com/watch?v=YpKgjUkuXdQ
Maine Professional and Structural Engineer
American Concrete Industries
www.americanconcrete.com
RE: Fiber reinforced concrete slabs on grade
And I wonder how it fares if moisture hits the whiskers?
RE: Fiber reinforced concrete slabs on grade
Brad805....fiber dosages are generally about 1 percent by weight. For polypropylene fibers....that's a lot of fiber, but they stretch so you need more. For steel, that's reasonable and it was the starting point for all dosage rates.
RE: Fiber reinforced concrete slabs on grade
Includes a worked example for comparison too.
RE: Fiber reinforced concrete slabs on grade
Richard A. Cornelius, P.E.
WWW.amlinereast.com
RE: Fiber reinforced concrete slabs on grade
RE: Fiber reinforced concrete slabs on grade
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.