Is it just me or am I crazy.
Is it just me or am I crazy.
(OP)
Im a senior materials tech for a local D.O.T.
My latest assignment has brought me to a bridge deck that has some serious cracking issues in the entire slab, there are no prestress members or post tension cables present fyi.
The materials P.E. over our department instructed me to use my coring drill to take cores 12" deep, and to "just cut through the rebar". Then just patch the holes back with ordinary post hole mix at a low w/c ratio. The consultant firm hired to oversee the coring only showed up on the first day, and no one bother to mark my core locations. I am using some rudimentary measurements on a single sheet from the as-builts, that I have no idea who signed off on. To top it off, the P.E. told me to just break the cylinders in the compression machine, even if they have rebar in them, to which I immediately told him the ASTM C42 explicitly states to not break them if reinforcement is present, he did really even care.
I cant help but disagree with every decision made, am I crazy?
My personal opinion is this, determine safe locations for rebar (structural p.e.), mark them (consultants job), patch them with fast set concrete or high strength grout(my job), and trim them in accordance with the ASTM and avoid all reinforcement in my test cylinders to determine a true strength. But what do I know, I only have a G.E.D.
My latest assignment has brought me to a bridge deck that has some serious cracking issues in the entire slab, there are no prestress members or post tension cables present fyi.
The materials P.E. over our department instructed me to use my coring drill to take cores 12" deep, and to "just cut through the rebar". Then just patch the holes back with ordinary post hole mix at a low w/c ratio. The consultant firm hired to oversee the coring only showed up on the first day, and no one bother to mark my core locations. I am using some rudimentary measurements on a single sheet from the as-builts, that I have no idea who signed off on. To top it off, the P.E. told me to just break the cylinders in the compression machine, even if they have rebar in them, to which I immediately told him the ASTM C42 explicitly states to not break them if reinforcement is present, he did really even care.
I cant help but disagree with every decision made, am I crazy?
My personal opinion is this, determine safe locations for rebar (structural p.e.), mark them (consultants job), patch them with fast set concrete or high strength grout(my job), and trim them in accordance with the ASTM and avoid all reinforcement in my test cylinders to determine a true strength. But what do I know, I only have a G.E.D.






RE: Is it just me or am I crazy.
If that is not possible, proceed only by following written instructions.
Re breaking cores with rebar, just note the presence of rebar in the comments section, adding that the results are therefore not valid.
RE: Is it just me or am I crazy.
RE: Is it just me or am I crazy.
I would agree with your approach. There is no reason to core through steel if you can avoid it with a re-bar detector easily, and even if the cores have some re-bar, as you say, you can trim the sample and get it right.
Apsix had good advice, get instructions on writing. Maybe tell him you can get the samples without re-bar on them.
I do not think being right is going to help you though!
RE: Is it just me or am I crazy.
RE: Is it just me or am I crazy.
RE: Is it just me or am I crazy.
If rebar crosses a potential break plane the test will be affected.
RE: Is it just me or am I crazy.
Just because he has a PhD doesn't mean that he knows anything but theory. In this case, he's blowing the theory and the common sense.
Stick to your guns... have him join here and post his reasoning for doing it "his" way. That will be an interesting thread. Good luck.
RE: Is it just me or am I crazy.
RE: Is it just me or am I crazy.
Don't get me wrong, it definitely can mean something depending on the individual. However, having the PE or PhD doesn't qualify ones knowledge outright.
Testing the core with the steel in it would be foolish and quite possibly could damage very expensive testing equipment.
If I put a cylinder in our testing equipment that had steel in it or instructed someone else to do so, I'd probably lose my job.
RE: Is it just me or am I crazy.
His PhD doesn't give him authority over truth.
RE: Is it just me or am I crazy.
RE: Is it just me or am I crazy.
That got a good chuckle out of me....the funniest part being that I have seen it actually happen.
RE: Is it just me or am I crazy.
What size core are you using? 2" diameter? For any of the above mentioned bridge decks, you will be hard pressed to find any area free of rebar greater than about 6" x 6" and that depends on the top and bottom mats of rebar being insync. Moreover, depending on the spans you will likely see some large rebar, #8 or larger in the postive or negative moment areas, which I think would tear your core up before you finish.
And be mindful of the last few inches of coring....don't want to lose that core to the river or highway below!!
As to strength concerns, I wouldn't not be too concerned with that for a small diameter core. I would be more concerned about the service conditions following the coring and patching....use the higher strength mix for better durability, adhesion to existing so as to prevent as much water ingress as possible. Ultimately though, the deck will wear much faster here....though if it's cracked and a candidate for possible replacement, it won't really matter anyway.
Good luck.
Regards,
![[pipe] pipe](https://www.tipmaster.com/images/pipe.gif)
Qshake
Eng-Tips Forums:Real Solutions for Real Problems Really Quick.
RE: Is it just me or am I crazy.
Im no bridge engineer, so I cant tell you what exactly its design is, it has a 4 spans, with a series of columns in between, it is about 24" thick.
The rebar in the deck close to the approach slabs gets much more dense, but I still yielded several rebar free samples.
While the compression test would be the tell all method for determining compressive strength, I also dont see the logic in drilling dozens of 12" deep holes in an already damaged and previously repaired bridge, then fill them with post hole mix of all things. When there are so many other non-destructible methods of determining in place strength of concrete.
RE: Is it just me or am I crazy.
I would save the upper 3 or 4 inches of the core for a petrographic examination. That's the area most affected by placement, environment, and serviceability issues.
As for missing the rebar...there are several methods available to detect the rebar pattern, even if you don't have drawings. As Qshake noted, the rebar will be tight...but if you check upper and lower mats, you should be able to miss most of it...sometimes you just have to cut through..but we don't just cut and not worry about it...we try to miss the rebar. If we can't then we cut in the most innocuous area that we can.
Now...go kick your P.E. in the a$$ and tell him to read this thread!! As graybeach noted, it's ridiculous to not listen to a Senior Tech. Most of them know more than the P.E. about what's important, particularly when it comes to testing. I know...I was a tech before I was a P.E.
RE: Is it just me or am I crazy.
As much as the Zircon MT-6 is touted by Luke Snell, I have had hard time locating the pattern, once I find an offset without rebar I stay with it the rest of length of the bridge.
The engineer would probably raise an eyebrow at me if I told him to do a petro on it. Too bad he wasted the tops and compressed them already, lol.
I would love to kick him in the arse, but these times are tough, I need the job.
RE: Is it just me or am I crazy.