Foundation Stabilization and Repair/filling rusted steel support post with cement?
QUESTION: I have just discovered that all three of the steel support posts (probably from 1960’s construction) under my screened porch are rusting out and the porch is in danger of sagging or falling down if this isn’t corrected.
The posts are hollow and one has small rusted out holes near ground level. One is totally rusted out and not supporting anything.
They are encased in cedar to match the lower decks and clearly visible, so it will be a BIG job to tear off railings and decking to get to them, dig them out and replace them (probably with 14 foot 6x6 pressure treated lumber).
I’ve read that filling a pipe with concrete makes it stronger:
It would save a HUGE amount of time, energy and money if I could just fill the posts with concrete and not have to tear up the deck to replace them.
Also, it looks like the tops of the beams are covered by 3 joined boards so that I would have to drill down 3 to 5 inches to reach the center of the hollow post.
If I were to try this:
1.) How large a hole would I need to make to be able to “force” concrete into it? This is the most critical question. I'd like to drill the smallest hole I can get away with (1/4 to 1/2 inch diameter would be great!)
2.) How could I force the concrete through the hole? Would it flow down a funnel? What size funnel opening? Is there anything that I could use to “inject” concrete through the hole? (like a turkey baster or some kind of syringe?
3.) What if I filled the steel post with the QUIKRETE Fast-Setting Concrete Mix where you just add water and let it set? (no mixing) Would that work? Would another concrete mix be better or “safer” for this purpose?
4.) Would there be any problem with filling the first few inches at base of the steel post first and then filling the rest a few days later?
5.) Would it be better to fill the bottom few inches of the post with a different kind of concrete (such as the ones with bits of plastic fiber mixed into it so it won't crack) and then a different concrete on top of it?
5.) If I wrapped the damaged areas of the post with duct tape (or something similar), would that hold the concrete in long enough for it to set? If this won't work, what if I coated the damaged area with mortar mix first?
6.) Would the concrete be strong enough to hold up the deck as the steel continues to rust away? Is there a way to make it stronger? Or something I could paint on the exposed steel to make it last longer?
7.) What are the dangers of trying this (other than the concrete might leak out the holes?)
8.) Will filling the cast iron posts with cement cause any other problems?
9.) If I succeeded in this, would it be a permanent solution or only a temporary fix that would have to be dealt with again in a few years?
I have never used concrete before. I apologize if I'm asking dumb questions!
Thanks in advance for any thoughts or suggestions you may be able to offer!
There are several options here.
To save time and repetitive emails, could you send me a picture
That will help me help you.
---------- FOLLOW-UP ----------
QUESTION: Thanks for your resonse.
Here are the pictures you requested.
Since I first wrote to you, I talked with a contractor said that steel set in concrete rusts and pressure treated lumber set in concrete rots, and there’s nothing you can do to prevent it in the long run… It was kind of six of one and half dozen of the other. Do you agree with that?
Another contractor said that the steel posts below my porch were still good (not rusted) above ground level so I could just build another platform on top of the existing concrete base and poor fresh cement around the steel posts and that would protect them. (The posts only seem to have rusted where dirt has piled up over the concrete base.)
But couldn’t a steel post continue to rust in the cement and gradually collapse and slide down inside the cement in that situation?
What if I screwed long galvanized screws into the good steel above the rusted areas (so that they extended outside the metal pole an inch or two) and then poured concrete over them? (I’d put jacks in before I tried this.) Would the galvanized screws prevent the posts from slipping down inside the concrete even if the bottom of the post continued to rust? Would they jeopardize the integrity of the steel post? If I set some screws right at the top of the cement, then at least I could see the damage if the post started to slide down into the concrete base…
Also, one of them appears to only be slightly rusted. If I gently dug away the dirt and dried the steel posts, is there anything I could treat the rust with that might also strengthen the steel? (something like Rustoleum and Bondo?) Is there any product that would be strong enough to fill in the holes and "repair" the post from the bottom?
Thanks in advance for any ideas or suggestions you may be able to offer.
Here is a no BS option.
If it were me I would pick up a piece of pipe that had an ID similar to the OD of the damaged pipe supports. Have the repair pipe sections split down the middle to allow for a wrap around the damaged pipe. The repair " split" section should be a foot long or so. I would then get some pieces of say, 3/8 by 8" plate, say foot in length or so. Have a radius torched in the plate to allow for a good fit around the damaged pipe. Assemble this at each pipe and field weld together. I am assuming that the damaged pipe is embedded in a concrete footing. If so,
remove the dirt son the plate can rest on top of the concrete for bearing.
You can have the parts made at a local weld shop and then have them or someone else come out to do the field welding. As an added extra security, assuming there is a footing, add a couple of holes in the plate and anchor to the footing to resist lateral movement and uplift on the structure above from wind loads.
When completed, coat all bare steel with either an epoxy or cold zinc paint.
This should be a cost effective and effective approach.