Probably part of the problem!
Posted on 07/11/2007 9:00:02 PM PDT by Ernest_at_the_Beach
It is used in materials testing before a meterial, connection or item can be relied upon by the designer for use in his design. ASTM standards and other similar standards govern much of design and construction.
Most people don't understand that in commercial construction, unlike much of residential construction, the contractor or the tradesman does not design the element, select the materials or, in most cases, even select the connection method. Such items are handled by professional designers and the contractors just determine "means and methods" to execute what is shown on the documents.
When a lift falls, a trench collapses, a schaffold breaks, a concrete form or false-work breaks or a heat torch cacthes a roof renovation on fire, you can bet on "contractor error." But even if the tradesman or his boss, for cost or ignorance, selected the wrong epoxy, the basic design was stupid in my opinion, and the first cause in any intelligent forensic review.
Section of ceiling tumbles in tunnel (Boston Big Dig I-90/I-93, One Dead)
How do you explain the roof control plans of most underground mines?
That would explain Teddy Kennedy, another unglued project.
Really? I am an engineer, and I didn't know that. With rapid set cements, they gain strength earlier, and contine on forever getting stronger. I've used epoxies for decades, and never knew fast setting stuff would actually lose strength. I know of no other material for bonging that does this without some outside force like UV degradation, which didn't happen in the tunnel.
The builders used the material specified. It's the designers who are at fault here. They should go to jail for manslaughter.
Thank God ignrant people don't make law! Epoxies are used every day for anchoring in concrete. It's epoxy anchoring compound, not just some generic glue you'd find at walmart. They just chose the wrong kind for the application.
a fully bedded rock anchor is a different animal than a simple anchor bolt, IMHO.
Next time I have a chance I will ask a fellow I know who has done some work on mined caves converted to warehousing and office what he knows of the distintion.
If I was going to arm chair design a drilled in epoxy aided anchor like this, I would have deep embedment and the anchors angled in opposition to each other so as to have a tension put upon another element to help keep it in place.
Any mining engineers out there with life safety structural credentials?
Threaded inserts should have been placed in the concrete before the concrete was poured, but given the way the design was done on the fly, the epoxied anchors should have held if properly specified and installed. The design sucked, becaus e there was not enough redundancy or factor of safety, obviously.
Bzzzt. Wrong. Happens all the time, by proper design. There are lots of products specifically desigened to do just this, but the key is to get the embedment length long enough so the pullout strength is higher than the compressive strenght of the concrete. It's not easy to do, as everything has to be spot on. Mechanical anchoring systems would have been much beter, but epoxy wasn't a definite no, as long as it had been properly specified.
Modern materials are amazing, and it’s not just some simple glue you buy at walmart.
Probably part of the problem!
DAMN TYPO! LOL! Bonding, I meant to say, obviously.
Uhhh..... it was reported that the problem was with the use of epoxy since the day the accident happened. Not sure why this is being reported as something new.
I know, I know....I’m just sayin’...
I’m not an engineer, but I could tell that there would be problems of some sort with this project when I visited Boston as a tourist about three years ago. At that time the project was already years behind schedule and billions over budget. Despite this, the downtown dig was still an open trench with lots of braces and cement forms everywhere. I was there for three days and never saw more that two dozen workers or so, many of them supervisors going in and out of construction trailers. My impression was one of a gravy train for the unions with all involved determined to move it forward as slow as possible so the project had turned into a job for life. I suspect that their amount of overtime took precedence over quality of work concerns.
the National Transportation Safety Board said Tuesday.
They were making sure .,....
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