Potential corrosion of the steel rebars within retaining wall
Potential corrosion of the steel rebars within retaining wall
(OP)
Is there any way to estimate the effective life span of steel reinforcement in a wet environment?
Here is the problem:
The rebars are grouted and located approx 3" or less from the face of the wall.
Where the seepage through retaining wall is occurring, the seepage is through hairline cracks and through grout between blocks. The worst case scenario is to assume that the rebars are in constantly wet condition.
Soil samples of on-site soils adjacent to the wall indicate:
- pH of 8.01
- soluble sulfate content range of 210 to 270 ppm
- chloride content range of 1029 to 1437 ppm
- minimum electrical resistivity range of 4452 to 5936 ohm-cm.
Thanks a lot
Here is the problem:
The rebars are grouted and located approx 3" or less from the face of the wall.
Where the seepage through retaining wall is occurring, the seepage is through hairline cracks and through grout between blocks. The worst case scenario is to assume that the rebars are in constantly wet condition.
Soil samples of on-site soils adjacent to the wall indicate:
- pH of 8.01
- soluble sulfate content range of 210 to 270 ppm
- chloride content range of 1029 to 1437 ppm
- minimum electrical resistivity range of 4452 to 5936 ohm-cm.
Thanks a lot





RE: Potential corrosion of the steel rebars within retaining wall
RE: Potential corrosion of the steel rebars within retaining wall
My hunch is that you have a serious issue.
Top coating and sealing may be your only options.
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Rust never sleeps
Neither should your protection
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RE: Potential corrosion of the steel rebars within retaining wall
I suggest adding Zn anode rods against both sides of the wall (& within the wall if not fully grouted), wired to the rebar. From plots of corrosion vs. time where cathodic protection was retrofitted to already-corroding well casings, in Practical Handbook of Corrosion Control in Soils, CASTI (2000), this may add 2 years to the life of the steel.
RE: Potential corrosion of the steel rebars within retaining wall
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RE: Potential corrosion of the steel rebars within retaining wall
As an alternate to these sacrifical systems you could look inot having an impressed current system installed.
Either way you need to have a system in place to measure the corrosion currents so that you can check on the condition.
As long as the pH stays high you woun't have much damage. Back in the crevices the pH will begin to drop and pretty soon the wall will be bleading rust and the surface will start to spall as corrosion swells the bars.
= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection
http://www.trent-tube.com/contact/Tech_Assist.cfm
RE: Potential corrosion of the steel rebars within retaining wall
If the wall is too wet for flame spraying zinc, maybe can pressure grout with a cement-lime slurry -- gives some sealing to allow subsequent spraying & raises the pH. Ideal pH for steel is 11.9.
But, the best solution may be to tear down the wall, install better drainage, then build a proper one with coated steel and anodes and well sealed on the soil side.
RE: Potential corrosion of the steel rebars within retaining wall
Any comments on this are definetly welcome. Think of it like epoxy coated rebar with big chips in the coating.
I think Electrochemical chloride extraction and Re-alkalization are more aggressive approaches to remedial corrosion work. Cathodic protection is more for sustained prevention and long term durability.