Fiber reinforced concrete replace wire mesh? 3

[mathewbaker]

Hello everyone
Well I want to use polypropylene (or nylon) fiber as replacement of wiremesh in an elevated slab of composite metal decks. I just want to know is there any code or at least suggestions that suggest this substitution? (As manufacturer of the fiber recommend this)
Thanks

 

[henri2]

At the top of the page, you can search for what you want in eng-tips. Type in "fibermesh" and proceed from there. There are numerous posts regarding this subject.

 

[SperlingPE]

Fibermesh is for crack control only. If wire mesh is needed as bending reinforcement (for strength), the fiber mesh is not a substitute.

 

[miecz]

See thread507-144777.

 

[Qshake]

Fibers generally in low volumes are for crack control (dry shrinkage and temperature), however, large volumes of fibers - 0.5% can be used for strength.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[Taro]

Qshake, are there any building code evaluation reports that approve fibers for replacing structural rebar? The ones I have seen explicitly state that this is not allowed.

 

[miecz]

I'm still confused as to the benefits/uses of fibermesh, which is why I don't use it. I was under the impression that the major benefit of fibermesh was to control plastic shrinkage cracking, and that it had little effect on temperature shrinkage or strength. Is there an ACI publication that recommends design minimums for fiber reinforcing, to be used in lieu of Chapters 7 and 10 of ACI 318?

 

[COEngineeer]

I just thought you use fibermesh to increase your fc. It has nothing to do with reinforcement.

 

[twinnell]

Synthetic fiber reinforcing is not used to increase the compressive strenght of concrete.

Go to

http://www.fibermesh.com

for more information.

 

[mbullism]

ACI 302.1R-96 "Guide for Concrete Floor and Slab Construction", Section 5.8 "Reinforcement", Section 5.8.3 "Synthetic Fibers":

"Synthetic fibers are used in floors to minimize plastic shrinkage cracking of concrete. These fibers should not be used to replace temperature and shrinkage reinforcement because they have little impact on the behavior of concrete after it hardens."

 

[WillisV]

Please see my response at the bottom of this thread: thread507-156960

 

[Qshake]

My apologies....I don't think there are any codes that allow full replacement or 1:1 replacement. I didn't intend to mean or imply a full replacement. But ACI 544 and related documents present the mechanics on FRC such that less conventional reinforcing can be used.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[dik]

jmiec: polypropylene fibres retard the release of bleed water and in the process provide a more uniform initial hydration. This better disburses microcracking and hence improves shrinkage cracking... as I understand.

Dik

 

[SlideRuleEra]

mathewbaker - The Steel Deck Institute (SDI) allows steel fibers to be used instead of WWF for temperature & shrinkage reinforcement of composite metal decks. There is (at least) one product that is a BLEND of steel fibers and synthetic fibers that meets the SDI requirements. See this link

http://www.fibermesh.com/downloads/Composite Metal Decks.pdf

http://www.SlideRuleEra.net

 

[miecz]

dik-

I believe what you're referring to (and referred to in mbullism's post)is called "plastic shrinkage cracking" that occurs during the curing process, as opposed to shrinkage that occurs over months or years.

Aren't proper curing techniques supposed to prevent plastic shrinkage cracks?

 

[MALKOBANI]

Bekaert has steel fiber products ,Dramix, Wiremix and DramixDuo that replace the traditional WWM. They also have a free computer program called DRAMIX DRAPRO that designs the slab for different types of loading.

 

[dik]

jmiec: yes, but the PP fibres improve on this. Little can be done for the long term shrinkage, except for a 'contained plastic flow' for lower strength concretes. Over a period of time, lower strength concretes (<4500psi)exhibit a better plastic behaviour than elastic. Higher strength concretes behave more elastically and more brittle.

Dik

 

[jike]

It is my understanding that fibers cannot be used to replace flexural steel required for negative moment over beams or girders. The composite deck acts as the positive moment steel. The fibers or WWF is for shrinkage and temperature only.

 

[miecz]

I'd like to see this question put on a multiple choice test.

Choose the statement that you most closely agree with:

A. fibers are worthless
B. fibers help prevent plastic shrinkage cracking
C. fibers prevent long term shrinkage cracking
D. fibers prevent cracking due to temperature effects
E. fibers can be used to structurally reinforce concrete
F. fiber design is covered by the concrete institute
G. fiber design is covered by the metal deck institute
H. fibers increase the compressive strength of concrete

Apparently, I'm not the only one who is confused, and I think I know who is causing the confusion.

 

[dik]

B & D for a start... Dik