In using steel fiber in different structural and non-structural members; such as foundations, columns, beams, slabs, and precast units, is there any relation between the steel fiber length and the smallest dimension of the concrete member ?
dear sir,
plz go through the following link
https://www.hindawi.com/journals/ace/2014/217473/
Thank you Mr. Carlos for these information.
I hope that you give me the specification that mention the relation between fiber length and maximum aggregate size.
I think the aspect ratio (L/D) " Length / Diameter" is the more important variable in the using of steel fibers than its length only.
Dear Dr. Ahmed El-barbary
ACI Code put limitations on maximum aggregate size in relation with the smallest dimension of concrete member. So, is the any limitations on the length of steel fiber in relation with the smallest dimension of concrete member ?
Desta Al-Sherrawi, you could consider the tradicional recommendation for fiber reinforced shotcrete what sugests that the fiber length should be less than one third of the nozzle diameter in order to prevent clogging. So, an important aspect is workability: you have to verify if the fiber length is not too long that cause problems (take a look at this paper: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000601284). On the other hand, if the fiber length is close to the smaller dizer of the element, it could provide a wall effect orienting the fibers and improving the fiber reinforcement.
Dear Dr. Mohannad
the max aggregate size in concrete times 2 to 3 is the length of the fiber which is recommended
For laboratory tests, the maxim length of the fibers should be equal or less than one third of minimum dimension of the mold.
Dear Mr. Carlos Méndez-Esteban… you are so helpful. Thanks a lot
Thank you Mr. Amir, I'll be glad if you have a specification mention that.
Yes. in the ASTM C1609 in the section 7.1.3 you can see the requirements as:
7.1.3 The width and depth of test specimens shall be at least
three times the maximum fiber length.
Dear Mr. Amir.
This specification was Withdrawn 2006, can I depend on it ?
Yes, you can. Because by any update you see some minor modifications. even you can find new version of that standard
Dear Mr. Amir.
I think this specification was canceled in 2006 not update.
There is certainly a relation between fiber aspect ratio and grade of concrete. It matters for bond strength up to certain limit.
Dear Mr. Uday
My question was about the relation between the steel fiber length and the smallest dimension of the concrete member not about aspect ratio.
Thanks
Dear Mr. Ali
I think the steel fiber orientation is important in casting and in strength.
Dear Dr. Mohannad,
Take a look on this paper
https://www.researchgate.net/publication/304347176_EVALUATION_OF_MECHANICAL_PROPERTIES_OF_HIGH_PERFORMANCE_SELF-CONSOLIDATED_CONCRETE_ENHANCED_BY_DISCRETE_STEEL_AND_POLYPROPYLENE_FIBERS
Article EVALUATION OF MECHANICAL PROPERTIES OF HIGH PERFORMANCE SELF...
Thanks Mr. Ali for this article.
The concrete was self-consolidated.
The main reasone we use fiber is to prevent early cracks (first 2 hour the concrete has no tensile strength) . Later we want them be durable against tire load induced stress.
Thinner but longer (5 cm) is better. Thick ones are hard to compact in RCC pavements. Also, thick ones makes more gap between aggregate in fresh PCC concrete since they have good ressitance agisnt laying down the material.
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