AISC Greenbook designation - Concrete Mixes 1

[rscott]

I am performing a project that requires addition of metric measurements to standards that now are all US.

The concrete mix designs are per AISC greenbook - in the form:

520-C-2500 (520=lb cement "c"=aggrgate size 2500=psi).

The new designation will be metric in the form (I found this formula in a municipality requirement):

310 kg/M(cubed) C 20 MPa

My question is, the conversions do not seem right.

First, I don't know what the M(cubed) is, so I don't know how to crank it in.

Secondly, 2500 psi does not convert to 20 MPa (megpascal).

I may be way off base, and am unfamiliar with this discipline.

Can anyone help clarify for me? Thanks so much...

 

[austim]

hi rscott,

Your first question is simple, and the conversion is correct. M(cubed) is someone's representation of 'cubic metre'.

The 520 is pounds per cubic yard. At 1 cubic metre = 1.307 cubic yards, and 1 kg = 2.2046 pounds, you get 520*1.307/2.2046=308 kg/m^3. Round up to 310.

Your second comment is quite valid. 2500 psi converts to 2500/145.04=17.2 MPa. To round that up to 20 MPa seems like some dog-rough science to me. I would not be party to calling that a 20 MPa mix.

 

[rscott]

Thank you for your informative and very helpful response Austim.

This gives me the information needed to proceed with the project.

Again, Thanks!