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

 

[SlideRuleEra]

B

D (within limits)

F (ACI 302, Paragraphs 3.2.4.1 and 3.2.4.2 - perhaps other documents, too)

G "Steel Deck Institute Design Manual for Composite Decks, Form Decks and Roof Decks - No. 30" (as updated in 2003)

http://www.SlideRuleEra.net

 

[Ron]

Fiber only enhances some of the properties of the CONCRETE. It isn't intended to replace anything.

Agree with Dik and SRE.... and will add H..with reservations, as most of the fiber referred to these days is polypropylene fiber, which does little for compressive strength (and quite honestly...little for anything else), but steel fiber can be used very effectively for property enhancement, including an increase in compressive strength (though it gives a much higher percentage increase in flexural strength than it does in compressive strength)

 

[CJJS]

Fibers will increase fracture toughness, tensile strength, and flexural strength. It will not have a significant effect on compressive strength.

 

[twisted1]

PP fibers do nothing beyond plastic shrinkage cracking. Steel fibers are a different story but they vary widely in cost and effectiveness because of the way they are made. Bekaert makes several and theres a new one from this company,

http://www.polytorx.com

 

[MACSlabs]

In 2002 Dr. Easterling, PhD at VA-Tech and Co-Author of "Desiging with Composite Metal Decking Assemblies" tested steel fibers as an alternate to welded wire fabric used for temperature and shrinkage reinforcement in CMDs. The steel fibers performed very well and in 2003 the SDI ammendded their specifications, to include steel fiber with a minimum ARS of 80psi as an alternate to the welded wire on CMDs. Any supplemental reinforcement, such as rebar over the beams to reinforce against the negative forces must remain. In 2005, Skanska utilized this option on the 1.5 million sf Census Bureau in Wash-DC. (I had no idea how many people it takes to count.

Also, regarding welded wire fabric (W1.4, W2.0 or W2.9): What performance is expected from the light gage wwms? What formula supports it's use? I can only think of one, and it's the sub-grade drag formula; As = FLW/Fs, and this formula has been taken out of ACI 360.
For a good slab on grade, use a consertive control joint spacing to control the restraint drying shrinkage and fibers, either polypropylene, steel or a combination of the two, to enhance concrete properties that add to durability. Throw the wwm in the river.

 

[Prepakt1]

Some polymeric fibers, like KevlarTM, carbon fiber and ultra-high molecular weight polyethylene have better tensile strength than steel. Nylon is up there too, but not stonger than steel .The normal polypropalene fibre used in slabs has no relevant stength. If you are going to use fibre use nylon its much stronger then polypropalene for any purpose.

Intrusion Prepakt

http://www.marineconcrete.com

 

[boo1]

see article at:

http://www.structuremag.org/archives/2007/January 2007/p20-22C-BB-HighPerformance-Jan07.pdf

 

[csd72]

One of the reasons why you cannot use the fibers for reinforcement is because you cannot guarantee that the fibers are going to be evenly mixed throughout the concrete mix. You may have relatively few fibers at your critical stress region.

another reason is ductility. A 1 or 2" fiber can only stretch so far before it breaks!

 

[civilperson]

The list of answers should have "A" rephrased:
A. Not worth the cost and effort to obtain dependable results.
I then choose A.
The article cited by Parra-Montesinos say steel fibers were approved by ACI 318 for shear reinforcement in beams. Not found in my copy of ACI-318. Where do I look for this approval?

 

[Loui1]

There is one producer of synthetic fiber that can be used as flexural reinforcement on a slab on grade application. Of course, the dosage rates to achieve this are pretty high, in the range of 7 lb/cu yd for a 6" slab.

There are no fiber producers that will tell you they can resist the negative moment above suspended deck supports.

 

[miecz]

Testing by the Steel Deck Institute only adds to the confusion surrounding the fibers. In my mind, concrete reinforcing is covered by ACI and CRSI, not the Steel Deck Institute. The Steel Deck Institute should limit it's testing to metal deck.

The confusion continues when engineers take test data for steel fibers in elevated slabs on metal deck, and apply it to slabs-on-grade with polypropalene or nylon fibers.

Test data that shows that steel fibers compare favorably to welded wire fabric doesn't carry a lot of weight, as welded wire fabric never did anything to enhance concrete to begin with.