huangyhg

fibre reinforcement for slab on grades
we are designing loading dock slab on grade for trailer loadings. client don't like to use welded wire fabric due to its poor quality and having past bad experiences.
we want to suggest steel fibre reinforcement in concrete. it all depends on the fibres type. how it can work, it's modulus of rupture should be definatley different and all depends on fibres.
does anybody know it is good to use steel fibre reinforcement or epoxy coated rebars. only problem in rebars is that lot of time is needed for placing and it might be uneconomical also.
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steel fiber reinforcing is great for improveing impact resistance, toughness, etc of slabs. use it where you have abrasive loading like workshops for tracked equipment.
for a loading dock for pneumatic tired truck/trailer loading, you are much better with conventional reinforcing bars. depending on the loading and soil conditions, i sometimes use top and bottom layers. don't know why you want epoxy coating on the bars.
pay especial attention to the joints, because that is where most problems occur. keyed joints are no good, as the top section of the key will sometimes shear off. don't put dowels too close to the corners.
the joints are alawys the critical area if you have quality concrete.
since when are fibers considered "reinforcement"?
they can enhnace the properties of concrete but really do not reinforce it.
depending whether the application has hard or soft tires on the fork lifts, the type and properties of added materials (fibers, admixtures, etc.) will vary.
dick
i'd use conventional reinforcing and good quality concrete with a max slump of 3" and properly located joints and edge thickening around the loading dock pits. check the recommendations for 'pit kit' suppliers. also want to properly chair your reinforcing steel and main rfg should be located 2" from top with 1-1/2" deep sawcuts. also, reinforcing should be spaced to permit walking between the bars.
dik
dik,
don't know about spacing the bars that far apart. some concretors have mighty big feet! so do i, and i prefer to walk on the top mat.
i often space bars at 14-16" spacing...
dik
as in the case of conventional reinforcement, steel fibers will not prevent the cracking of the concrete. use of steel fibers thru the contraction joints will reduce the width of the joint openings and that increases the likelihood of cracking occuring between the joints. the cracks however should remain narrow. to keep all these cracks within acceptable limits, the mix has to be carefully engineered.

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