Concrete Measurement

[Contech2011]

Hi All,

We tend to ignore the volume of heavy rebars in any structure while ordering the concrete. Given that the yield of the concrete is allright, there remains some difference between theorotical quantities ordered (based on the dimensions from the drawings, offcourse) and the actual concrete being used.

Please shed some light on rebar volume and form misalignment effects on concrete volume.

Thanks

 

[dik]

I think your volumes loss due to reinforcing is relatively small, maybe in the order of 1%. Dimensional tolerance in formwork construction would likely be a larger amount and the degree of consolidation of the concrete due to vibration could also contribute (in particular to foundation work against soil). I'm not aware of any consideration of this in normal work.

Dik

 

[hokie66]

This can vary with location, but often depends on the ethics of the supplier. I have seen contractors order a given quantity and, when the truck arrives, order it to be emptied into a precisely sized box.

 

[Ron]

Agree with dik....this issue is irrelevant to the rebar, but dependant on the formwork tolerances.

 

[dik]

I was surprised in vibrating caissons for one of my buildings that the level of concrete 'dropped' nearly 1' (10") in the 40' length, likely due to consolidation to the adjacent soil. I always stipulate that the top 10' of piles and caissons be vibrated.

Dik