rorschach
Petroleum
- Aug 5, 2002
- 197
Here in Houston we have an issue that has been milling about in the local news media and on blogs and I'd like you guys' opinion on this so that I can put all of the hyperbole and denials in perspective.
The local transit authority has installed a electric tram that runs for 7-1/2 miles down main street in downtown Houston. No particular attention was paid by the construction crew to prevent current leakage from the rails into the surrounding soils. Several track switches have been damaged by stray current corrosion, and the latest test data I've seen from METRO on this shows a resistance of 250 ohms or less to the surrounding soil at any given spot along the tracks. We have a High water table, High Total Disolved Solids, and high salinity in the soil. This tram runs past several structures that are sensitive to damage to thier foundations. One, a 35 story twin office medical building in our Texas Medical Center who's architect added 5 additional floors to the building during construction after the foundation was laid but refused to add three more citing loss of safety margin. It also runs underneath two major freeway exchanges who's support pilings date back to the late 60's and which carry approximately 750,000 vehicles per day and is well known in town for it's design to cause harmonic vibrations in the vehicles passing over it (you feel like you are riding a bucking bronco after a few seconds), and it also runs over two bridges which have already been repaired once due to stray current damage. TxDOT refuses to inspect the freeway exchanges claiming that rebar embedded in concrete is immune to stray current corrosion. The owners of the building in the TMC have repeatedly asked the transit agency to solve the problem only to be told there is no problem, the rebar is embedded in concrete and is immune. Both TxDOT and the Metropolitan Transit Authority appear to be busy burying thier heads in the sand.
So how immune is Rebar in concrete?
The local transit authority has installed a electric tram that runs for 7-1/2 miles down main street in downtown Houston. No particular attention was paid by the construction crew to prevent current leakage from the rails into the surrounding soils. Several track switches have been damaged by stray current corrosion, and the latest test data I've seen from METRO on this shows a resistance of 250 ohms or less to the surrounding soil at any given spot along the tracks. We have a High water table, High Total Disolved Solids, and high salinity in the soil. This tram runs past several structures that are sensitive to damage to thier foundations. One, a 35 story twin office medical building in our Texas Medical Center who's architect added 5 additional floors to the building during construction after the foundation was laid but refused to add three more citing loss of safety margin. It also runs underneath two major freeway exchanges who's support pilings date back to the late 60's and which carry approximately 750,000 vehicles per day and is well known in town for it's design to cause harmonic vibrations in the vehicles passing over it (you feel like you are riding a bucking bronco after a few seconds), and it also runs over two bridges which have already been repaired once due to stray current damage. TxDOT refuses to inspect the freeway exchanges claiming that rebar embedded in concrete is immune to stray current corrosion. The owners of the building in the TMC have repeatedly asked the transit agency to solve the problem only to be told there is no problem, the rebar is embedded in concrete and is immune. Both TxDOT and the Metropolitan Transit Authority appear to be busy burying thier heads in the sand.
So how immune is Rebar in concrete?
