I am refurbishing a deck that is supported on 4″ steel columns almost 19′ tall. The steel is mildly rusted except at the bottom, where the installers were not carefull to keep the steel elevated and out of the dirt. They are starting to rust through at the bottoms. It seems unnecessarily expensive to replace the entire posts by temporarily supporting, raisng the footings, then installing new posts. My plan is to pour concrete around the existing posts to 8″ above grade, weld tabs to the existing steel to transfer support to the new footing, caulk the joint between the steel and the new concrete, clean and repaint the posts and call it done. Is this a good way to proceed?
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Are the welded tabs necessary? If the footing holds the column then what you're adding is more of a protective conical sleeve to keep the steel out of the dirt. As such concrete will have issues as it shrinks and cures. I would at least brush (wire brush in a grinder) and prime prior to pouring the sleeve. Dig away any earth to the foot of the column and then prime. The concrete will shrink away from the column creating a pocket for water to sit in with the steel. Use commercial polyurethane caulking for this after priming and pouring. DAP won't do it. Wire brush everything and give two good finish coats of oil-base.
Thanks for your response. The welded tabs may not be needed, but they will make me feel better.
I've had pretty good luck with painting rusty steel with rust converter. You want to scrape off flakes of rust, but it needs the rust in order to work--the paint has phosphoric acid that works like Parkerizing and changes the iron oxide into a phosphate that doesn't rust.
Thanks, Danno. Any particular brand of rust converter in mind?
http://www.eastwoodco.com/shopping/product/detailmain.jsp?itemID=1134&itemType=PRODUCT&iMainCat=373&iSubCat=374&iProductID=1134
This is good. Duro extend and some others are not. What about the inside of the column? I agree with your idea of tabs except I would think it would be better to cut off the bottom and weld on a plate that was solidly anchored to the concrete.
Mr. Mark,
Thanks. I've got a new bookmark in my list
I've been using something called "Rust Mort", but I've had it for a long time and don't know if it's still available.
Rust mort is terrific and still available. Also excellent is Corroless? which is used to paint drilling platforms in the North Sea.
http://www.corroless.com/ found their website. Looks like a great product. I will have to see if local autobody shops have it
I think the Eastwood product is actually Corroless. They used to sell it, but don't anymore. What they have seems identical and if you Froogle corroless the Eastwood product comes up. I haven't been able to find Corroless products anywhere else.
You're right, Mark. I think the Eastwood product is probably the best. And the best ain't cheap. That's my motto, at least
Googled it up and found this site. http://www.yearone.com/serverfiles/headline.asp?hid=A23AB55505
Sounds like great stuff, but would need a topcoat. I would like to find a one coat product.
Thanx for the input