ACI 318-14 Proportioning and Trial Mixtures

[Joseph W Balloni]

The updated ACI 318-14 code has eliminated the mix review procedures associated with the 'proportioning of concrete mixtures' section. The commentary even states that 'information was removed because it is not the responsibility of the licensed design professional to proportion concrete mixtures.' Further stating that the information can still be found in ACI 301 and ACI 214R.

It is my opinion that as design professionals we should be aware of the 'statistical accuracy' of concrete mixes being placed on site. This becomes even more pertinent for reinforced concrete structures, as opposed to steel structures with only footing/slab concrete. If AISC updated the code to state steel shop review was no longer required and not the responsibility of the design professional, I would take a similar stance. What is everyone's thought on this topic?

 

[ATSE]

Joseph, I don't believe your comparison is quite fair.
The engineer is still required to review the concrete mix design, but not proportion the mix. Mix proportioning is specialized.
Possibly a more appropriate comparison would be to A572 chemical composition - which most engineers don't know too much about, but can successfully design structural steel, including welded connections.
Also, the statistics of the concrete mix results must satisfy ACI 301, so the COV is accounted for in the reduction (phi) factors that structural designers use.