Concrete strength requirement!
Concrete strength requirement!
(OP)
Per ACI 318-08, table 4.2.1 and table 4.3.1, for any exposure condition above F1, the minimum required f'c is 4500 psi. Does it make sense? If we specify 4500 psi concrete for smaller projects where we use concrete for footings and retaininng walls only, we may not get another project next time from this client. What is your experience on this? Am I missing anything here?






RE: Concrete strength requirement!
That's what it means.
You don't make engineering decisions based on whether you might or might not get a job again. You make engineering decisions based on sound technical judgment. If you need to educate your client then do that, but don't let your client dictate your engineering decisions. It's your license, not his.
RE: Concrete strength requirement!
I think you did not understand my question. Your answer is academic than practical. My question was, does code allow to use lower compressive strength under this condition? Especially when you are dealing with less amount of concrete for small residential project for an example.
RE: Concrete strength requirement!
RE: Concrete strength requirement!
If it is soils, then Ron is correct as your small amount of footing concrete would be exposed. If the concrete is exposed to the attacking substances elsewhere, there may be some concrete that wouldn't be exposed and thus, per the code, not need the higher f'c value.
I saw nothing in Ron's answer that was "academic".
RE: Concrete strength requirement!
Doug Jenkins
Interactive Design Services
http://newtonexcelbach.wordpress.com/
RE: Concrete strength requirement!
RE: Concrete strength requirement!
RE: Concrete strength requirement!
Amen!!!
The incremental minor extra cost for strength is meaningless.
Here (Minneapolis/St. Paul) if you want to pour a driveway, you may not even get delivery of concrete from one of the better producers unless it is minimum 4000 psi with 5% air and 3" slump unless the purchaser signs off on the suppliers liability. The lost business to the supplier caused by poor concrete specifying is less than the liability and negotiating costs later if there is a problem.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: Concrete strength requirement!