How to repair steel culvert? Use concrete?

[vancouver]

I've seen concrete placed on galvanized steel pipe. Good plan?

 

[MTGreen]

Well I don't know from personal experience, but I would be concerned about how alkaline concrete would react with galvanizing and potential rust. Concrete has a pH of 12.5 to 13 which is pretty alkaline and here's the corrosion graph for galvanized:

So it looks like we're right at the limit for increased corrosion. This is theoretical of course it may be just fine in practice.
I'm sure others can chime in here that have first hand experience

 

[Larry Caldwell]

Why are you repairing it? Get it dry, hit it with cold galv, and it will last longer than you will.

 

[MF243RedTop]

That would work temporarily to fix the hole on the bottom side of the culvert... But it looks like there's a line of rust starting form all the way down... If you keep repairing it that way, I would be concerned about it's integrity eventually... Long term fix is replacement..

 

[Jstpssng]

Depending on how much weight you are putting across it and if it was set properly (it appears from your picture that it was) that could last a long time. Start trying to fix it and you may cause it to rust faster. As log as you have water setting in the culvert at time, it will rust.

 

[Alan W.]

Ive got one under the middle of my drive that is rusting away like yours. It is for my pond overflow.
I should have never used metal. Will replace it with ADS or RCP.
Dad had a large metal culvert pipe rusting away under his concrete drive. I found an ADS pipe that would just fit inside the old pipe then I formed and poured a load of grout between the two.

 

[Tinhack]

When I did my driveway entrance here, I covered the pipe with concrete then used tapered riprap approaches. I had to build it to State Road Requirements. Then about 12 years later, the state widened the road and removed mine. They replaced it with a pipe with only riprap tapers. They had a hard time getting mine out. It probably would have lasted 1000 years.

 

[ponytug]

Well I don't know from personal experience, but I would be concerned about how alkaline concrete would react with galvanizing and potential rust. Concrete has a pH of 12.5 to 13 which is pretty alkaline and here's the corrosion graph for galvanized:
View attachment 769064
So it looks like we're right at the limit for increased corrosion. This is theoretical of course it may be just fine in practice.
I'm sure others can chime in here that have first hand experience

X2

It is not a good idea to have water + concrete + galvanized sheet metal together. It is a long term recipe for corrosion.

If you want to patch yours for a few more years of use, barring a flood, it should work, but it isn't a stable repair.

Corrugated culverts are relatively easy to place, cheap compared with concrete, but they do wear out, especially if there is gravel or rocks flowing rough, sanding off the zinc galvanizing. Depending on your water chemistry, they can last ten or fifty years.

Personally, I prefer the newer plastic culverts, but you have to be careful to get them at the right slope, or you have erosion issues downstream due to higher water velocities.

All the best,

Peter

 

[vancouver]

Ok, very disappointed. I need encouragement that concrete is a good solution. I see engineers use concrete right over steel culvert.

 

[Jstpssng]

If that is what you want to do then do it. Don't ask a question, then complain when we don't tell you what you want to hear. Talk to one of the engineers and see how they would do it.