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Re: (erielack) More Cutoff info (2)

As Schuyler had pointed a few days back, a simplistic mixture of sand, 
cement & limestone +, and when mixed w/water, makes up concrete.  The 
various compression mixes available (2500psi, 3000psi, 4000psi, etc.) are 
determined by the ratio of material in the mix, affected by other things 
like water content of the mix, admixtures, and the outside air temperature 
when the mix is placed and drying; so the explanation from the consultant 
about limestone content would appear to be valid possibility.

Any time water penetrates into a concrete structure, coupled w/ the repeated 
freeze/thaw cycles over time, the concrete will begin to crack and heave, as 
well as invariably seeping to the underlying rebar, ultimately weakening the 
bond to the surrounding concrete, and over a longer period of decades, 
evetually rusts through the rebar...it's amazing that what starts out as a 
small inconsequential hairline crack 50-60 years ago could eventually be the 
cause of major structural failure/weakness of a bridge such as the DL&W span 
over the Delaware, particularly since the span hasn't had any major 
maintenence since the EL merger in 1960 (if not longer than that...)

Rich Behrendt
ELHS #384
- ----- Original Message ----- 
From: "Tim Stuy" <njmidland_@_verizon.net>
To: "Tupaczewski, Paul R (Paul)" <paultup_@_alcatel-lucent.com>
Cc: "J. Henry Priebe Jr." <root_@_net.bluemoon.net>; "Erie Lackawanna Mail 
List" <erielack_@_lists.elhts.org>
Sent: Wednesday, January 31, 2007 9:49 AM
Subject: Re: (erielack) More Cutoff info


>I wondered about this as well.  At the session in Blairstown on Monday I
> asked one the the engineering consultants about this.  He told me that the
> arches and the bases into the ground and the river on the Deleware River
> Viaduct are fine.  The upper arches that support the track deck are shot. 
> I
> asked about the Paulinskill Viaduct and he said it is fine and ready to 
> go.
> So why the difference between the two?  The consultant claimed that the
> Delaware River Viaduct was the first one built and that there were some
> significant changes made when they did the Paulinskill (and later,
> Tunkahannock).  He said the changes were in the size of the rebar and in
> limestone content.
>
> I don't know how true any of this is but at least it sounds plausible.
>
> Tim
>
>>
>>
>> Seriously? I know there's been some minor concrete leaching, but "new
>> arches?" Are they serious???
>>
>> Not being a civil engineer, I can't attest to the bridge's strength, but
>> having walked across it several times, it sure seems substantial to me.
>>
>>         - Paul
>>
>
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