Well Its April 15th - Let The Work Begin

[Henry]

I expect before they start any work on the Bridge, there will be some detour signs going up.  April 15th was the big rumor around that work would begin, so if anybody sees any activity let us know - I am sure Mike Cain will keep his eyes open also.

[BCota]

[BCota]

28 Day compressive strength of companion cylinders is over 9000# per square inch.  For some perspective, thats about triple the strength of a typical slab or basement.  Beams will continue gaining strength forever (with diminishing returns) but will top out around 10,000# at 90 days or so (you'll be driving on it by then).  6000# is the required strength per the design calculations but we end up with a lot higher because we need to get the strength quick in order to remove the beams from the forms on a daily basis. 

[Shadylane08]

When we poured the reservoir up in Irasburg we had a design strength of 5000# at 28 days, but with the mix that was used from carroll our 7 day break was almost at design strength therefore our 28day break ended up being up around 7000# I think.  Well to get to the point the structual engineer was really worried about this saying that with it getting to strength too quick it will actually start cracking, therefor sacrificing the durability and life of the reservoir.  Do you not have to worry about this with prestressed concrete?

[Mike Raburn]

I would hope you would NOT have to worry about the pre stress.
It is done at a factory in a "controlled" environment.
QA/QC reports from the plant AND a rep from the owner.

What the hell ever happened to handshakes and words?

Oh, lawyers.

TORT REFORM!

[BCota]

The purpose of prestressing is to prevent cracking due to flexure...the early age cracking that you are referring to is due to temperature; when concrete gets strong fast it tends to be really hot too and that can cause it to crack when it cools down -- these beams got to 5000# in about 16 hrs (type III cement) but it was achieved through careful, deliberate proportioning of the ingredients rather than high curing temperature -- they will never crack under any foreseeable circumstances.

[BCota]

Vermont is actually an excellent state with respect to their oversight of construction operations; Many of the other state DOT's that we do work for will outsource quality assurance inspectors to observe means and methods and ensure that everything is to spec while VAOT sends actual state employees (which I imagine is probably cheaper too).  The use of outsourced inspectors is kinda like letting a valet park your car for you -- on a couple levels.