I work for a design/build construction company who never tests concrete......

[ARS97]

Just like the title says. I'm a structural engineer who works for a medium sized construction company who specializes in industrial projects. These projects usually involve some form of structural concrete, which is typically limited to foundations. (Once in a great while I'll have to deal with something a little more specialized in terms of concrete, but it's rare.) Here's the problem - they never test concrete, unless it's required in the project specifications. (This is also rare since the customers that we deal with normally are not typically "heavy" in terms of specifications.....they are usually looking to us to provide them an adequate product with minimal specifications or requirements.) Basically, when I call out a concrete strength on the design drawings, they call up the local concrete plant, request a mix that meets this strength requirement, and never verify that they're actually getting what they paid for. There are a few reasons why this is done:
1) Concrete testing requires additional cost
2) They think that by simply placing an order for a certain concrete strength is the end of their liability. They think that the batch plant is then responsible for taking it from there.

I've preached about things like "negligence" and "design professional", but it's a hard sell. Aside from citing code requirements (ACI, IBC), how would you approach this? (Citing code requirements isn't usually very convincing to people who don't pay attention to codes.) I'm trying to change the quality control mindset of an entire company, which is a daunting task.

Any help would be appreciated! (NOTE - I also posted this in the concrete testing forum)

 

[haynewp]

The PE behind the project is taking the risk of not requiring testing. I don't design industrial structures but the standard of care should be to require testing and not just specify the f'c required.

 

[kylesito]

It's a little shady but I am not sure it's anything to unethical or anything. I actually see the point that if they request a certain strength then they have to trust the company is going to deliver what they say they will...why should your company need to verify this? I recently watched a case where a contractor won a huge settlement from a supplier of geogrid. The geogrid failed and the wall collapsed. It was proven though that the contractor had asked for a certain product but received one of inferior value from the supplier (although documented as having equal properties) and so the supplier was held liable for deliver a product that didn't meet the requirements.

Yes, I would certainly like to know personally. Maybe you could convince them to test 1 out of 10 jobs just so you had a record of some QA and could show some kind of due diligence if there was ever a problem.

PE, SE
Eastern United States

"If a builder builds a house for someone, and does not construct it properly, and the house which he built falls in and kills its owner, then that builder shall be put to death!"
~Code of Hammurabi

 

[ARS97]

Well, typically I am the PE.....I'm their only engineer. If I require testing and note it on the drawings, what else can I do? If the contractor (the company I work for) and the customer don't care, then I'm pretty much alone on the issue.

 

[JAE]

I would simply require it and insist that it be done as a public safety/welfare issue (that is your prime directive as a PE).

If they don't do it then at that point it is up to you to determine in your mind whether there is a public safety issue. If there is, then it is your obligation (under engineering ethics guidelines) to report this to higher authorities.

Having said that, it may be that even at f'c = 2500 psi for footings, there might not be a public safety issue.

 

[ARS97]

JAE - I'm not sure I'm following on the f'c = 2,500 psi comment.....unless you're referring to a F0 exposure (no freeze/thaw effect), which is rarely the case (based on how I read ACI 318-11). I typically go with a F1 or F2 since there's usually a portion of the foundation exposed to the freeze/thaw.....

 

[paddingtongreen]

As a practical matter, unless I had a better job to go to, I would design for 2000# concrete and specify 3000#. Part of an engineer's job is find a way around the administrator's roadblocks.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[ARS97]

paddingtongreen - it's a great place to work.....but I agree....sometimes I need to get creative....

 

[JAE]

I was just suggesting that footings don't always need very high compressive strength - similar to what paddingtongreen states in better manner.

 

[haynewp]

It depends on the public safety first then on how strongly you feel about it anyway if there is no safety issue. You could state you are not going to stamp any more drawings unless they start testing, I would have a back plan if they take offense to that and consider hiring someone else.

 

[JedClampett]

You're going to have to make them think about depositions and trials. If a disaster happens (concrete cracking, falling apart, etc.), the plaintiff is going to get a structural engineer to testify that it's standard practice to take cylinders and test them for strength. If the lawyer is smart, he'll have some example cylinders. This engineer is also going to testify that he's seen this and that problem, due to bad batches of concrete, that were avoided by on site testing. What is your side going to say? "We trusted the batch plant?" "We asked for 4000 psi concrete and that's the end of the story?"
What kind of margins do you operate in, that concrete testing makes a difference? Doesn't every company have a risk management department that slaps the hands of people who cut corners?

 

[hawkaz]

What type of usage do you have. If you are talking about 12"+ thick equipment pads on grade, where soil bearing or vibration issues govern- concrete strength may not be critical. If you are talking columns, walls, elevated slabs... you have a very different issue.

 

[dicksewerrat]

Who is paying for the malpractice insurance?

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[fel3]

A few agencies I have dealt with over the years require evidence of concrete testing (structural concrete, that is) as a condition of their construction permit. Before they sign off on the construction, they want copies of test results that show the concrete passed muster. Sometimes they also required soil test results. What about in your neck of the woods? It would sure help your cause if the permitting agencies you were dealing required test results.

==========
"Is it the only lesson of history that mankind is unteachable?"
--Winston S. Churchill

 

[shobroco]

I have seen one (1) batch in 30 years that failed to meet spec (yes, the vast majority were untested) and the readymix company paid to replace the slab that had been poured. Tests I saw last week showed 28-29 MPa results for a concrete specified at 25. Look at it from the ready-mix guy's point of view: you spec 25 & he supplies 23, no end of trouble. You spec 25 & he supplies 27, everyone is happy. In design-build, everyone usually uses the same suppliers most of the time, so you must have a relationship with them; tell them you want some comfort & see random test results from a bunch of their projects. Someone will be asking for tests, even if you're not.

 

[haynewp]

Yeah, tell them you are stamping the drawings and specs and you want it tested unless you personally would accept it otherwise for whatever reason which apparently you don't. Unless upper management is stupid they will listen, if not look for other employment. They should respect you as the PE on the project. It shouldn't have to be a big discussion about it at your work or on this website.

 

[Ron]

As others have noted, footing/foundation concrete might have a slightly lower priority for testing; however, some testing should be done.

Another point is that you must consider specifying concrete acceptance by other than strength alone. As shobroco noted, rarely will the strength be an issue for the ready-mix supplier...durability is a different matter. Specify the concrete to achieve both strength and durability for the application and then test it at reasonable intervals.

...and yes, it is a standard of care issue for which the design engineer bears responsibility.

 

[OHIOMatt]

One thought on this issue. My state is taking the approach that the third party testing must be hired by the owner and not the general contractor. It has come back as a plan check comment when I tried to place the responsibilty on the GC in notes or specifications.

With that said, I would take the approach the owner need to have the testing done. They will ultimatley pay for it, either as a pass through, increased bid price, or directly to the testing agency. The fee associated with testing cylinders is exteremely minor.

Of a greater concern, I would assume if they are not testing concrete then they are not testing the soils that support it. In my experience soils are where the greatest liabilty lies in this case.

 

[FLCraneBuilder]

Similar situaiton with mild steel plate & beams. We require certs to be provided for only about 10% of our projects. But on those that we do get certs, the properties ALWAYS far exceede the minimum yeild and tensile values. I suspect that a reputable concrete plant will be very good at controlling this. Its what they do for a living and I'd like to think they are experts at it.

And I wholeheartedly agree with Ohio Matt - the soil is where the problems begin

 

[SteveGregory]

OhioMatt has the right approach. Special Inspections, Geotechnical soils and material testing should be contracted directly by the owner. This is a good way for the owner to verify what he is paying for. Otherwise, if the G.C. is hiring the testing agency, isn't this like the fox guarding the henhouse?