2500 psi concrete

[palves]

I have a contractor who wants to use 2500 psi concrete, but usually use a minimum of 3000 psi on all of my projects. The thing is, this has just become standard operating procedure for me over the years and I have no real reason to back it up other than "It's what I've always done." So, does anybody out there use/not use 2500 psi and have a solid reasoning behind their decision? I'm curious what people do and welcome any and all reasons so let 'em fly. Thanks!

 

[cvg]

you're giving the ready-mix plant operator way too much credit. If you are getting crappy concrete, only two possible reasons. Either 1) they are trying to pull a fast one to save a couple dollars or b) some sort of screw-up: either they messed up the mix proportions at the plant or driver got lost and added a lot of water right before he showed up on site

well, I guess that's three reasons

 

[rapt]

I would like to see the defense if it ever went to court.

Well Judge, I really wanted 3500psi concrete strength because it is much better so I ordered 2500psi knowing that they always supply much higher at these low strengths and as I asked for 2500 they charge me less. Unfortunately they actually supplied 2500psi and that is not fair. So it is their fault!

 

[ARKeng]

This is common in Southern Nevada also... with the following caveat.

You can specify/buy any strength of concrete you want. It's just that the design must be based on f'c=2500 psi to avoid the Special Inspection requirement. For example, you can tell them to provide 3000 psi and just indicate on your notes that your design is based on 2500 psi and avoid the SI. The more common practice here is to require 4000 or 4500 psi (for soil sulfate durability concerns) and do the strength design calcs based on 2500 psi.

 

[hokie66]

Do I detect a hint of fraud in Nevada? Fancy that.

 

[Ron]

Tell the contractor what YOU want and stick to it. Strength might not be an issue but durability certainly is as others have noted.