Steel Fiber Reinforced Foundation 1

[puffy333]

A co-worker has asked me to help him investigate the properties of a steel fiber reinforced concrete foundation. We're looking for how it affects f'c, (phi)Vc, and how it compares to rebar reinforced foundations. All we were able to find online were research papers that had no difinitive explanations that apply to our questions, and ACI was no help due to the fact that this is more of a European practice. Any help leading us in the right direction would be great.

Thanks!

 

[civilperson]

Very interested to see your results! Previous trials have shown no benefit over plain concrete since the tension location and orientation is the only spot steel fibers might help reinforced concrete. Minimum clearance to the face is hard to maintain without rust stains and oxide penetration.

 

[hokie66]

Fibers are not a replacement for reinforcement. The principle benefit of steel fibers is in increasing surface toughness or abrasion resistance. This is especially important in industrial pavements in areas like workshops for tracked vehicles.

 

[miningman]

You might want to talk to some experienced underground mining personnel before you go down this road. The average geotechnical engineer will be all in favour of adding steel fibres to shotcrete.. improves strength etc etc but he wont tell you about the number of minor hand injuries that occur just working near this stuff, or increased pump maintenance costs due to steel fibres finding a way into pumps, or electric cables etc

If there was any possibility of personnel working on their backs or having their hands near this stuff, I wouldnt recommend its use.

 

[Riggly]

Apart from the other reasons mentioned above, steel fiber can be used to control temperature and shrinkage cracks, but not reliable with flexural crack control. As to how it affects the compressive strength of concrete - it don't think it does. Have you seen steel fiber? They are not actually 'fiber' as in the sense of the fine thread-like fiber that we normally associate with the term fiber. I presume that's why you were thinking of how they affect the compressive steel. They are small rigid pieces of steel (at least those that I have seen).

If your foundation is thick enough and if the flexural load can be safely carried by the plane concrete, you can use it. But you also have to take into consideration the application of the fiber. Further, any moisture barrier can be punctured by the steel fiber.

Note: Fiber reinforcement has also been successfully used in 'isotropic bridge decks' which utilizes them only for temperature and shrinkage control - where no longitudinal or transverse reinforcment is used.

 

[Ron]

Steel fiber enhances the properties of the concrete only. It should not be a replacement for conventional reinforcement.

Steel fibers in concrete come under ACI Committee 544. Most research and observation of actual practice shows that ductile steel fibers increase the capability to control cracks in concrete and enhance the compressive, tensile, and flexural strength parameters.

You might do a general keyword search in Eng-Tips for more info...two examples follow....

http://eng-tips.com/viewthread.cfm?qid=108184

http://eng-tips.com/viewthread.cfm?qid=163237