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Re: Best Article I've Read on Reasons to Reactivate the Rockaway Beach Line

Posted by ClearAspect on Mon May 7 15:22:02 2012, in response to Re: Best Article I've Read on Reasons to Reactivate the Rockaway Beach Line, posted by Train Man Paul : Metro-North's Best Conductor FOR ALL 3 LINES!!! on Mon May 7 14:56:14 2012.

Weather causes the concrete the crumble naturally, heating, chills, the expansion and contractions over time inevitably cause cracks, this is called fatigue cracking and once water gets into those cracks and freezes in the winter the cracks become bigger. Usually steel rebar exposed will rust and expand causing further cracking in the area where the concrete is compromised. However there is a point where it stops because stress has been released in the cracking of the concrete and the rust isn't a disease it doesn't spread far from its origin, rather where the steel is exposed. So what will happen is that the engineers will test the integrity of the walls, visual inspection results, strain measurements, acoustic emission (AE) monitoring, ultrasonic scanning (UT) and related types of nondestructive testing (NDT) like dye penetrant tests (PT), magnetic particle (MT) tests, ultrasonic (UT) scanning and acoustic emission (AE) monitoring. See where the steel is exposed and usually do a patch job where the concrete will be removed, if the engineers determine that its not that severe, the steel rebar replaced and then new concrete poured again. Sometimes nature taking over may give the structure an increased life because its not taking the loads and stresses it used to take when heavy trains ran over them, nor are they exposed (mainly in road bridges) to things like road salt or other things that could destroy the steel faster than natural forces could. So you could be right but I've walked along that line and a lot of the steel looks to be in good shape. I hope it could be salvaged rather than needing a full replacement.


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