Repairing Damaged Concrete Post on 1930s Prefab Garage (Concrete cancer)

[sillettx]

Hi, first time using a forum, so I hope I'm doing this right. I'm looking for advice from anyone who might have experience with this.

I'm a fairly experienced DIYer and up for trying something new. I have a pre-cast garage that I believe was put up in the 1930s. Almost everything is fine with it, but there's one panel with a problem—please see the picture below. One post has deteriorated badly.
I'm not concerned from a structural point of view because everything else is solid and the roof is quite light. I'm just looking for advice on what I can do to repair this.

My thought was to:

• Cut out the rusted rebar
• Tie in a new piece of rebar
• Build shuttering around it
• Pour in concrete to form a replacement section and seal it in

I'm wondering if anyone has any ideas about products that might work better or a more effective approach to this repair.


Many thanks!

 

[stevie888]

First off I very much doubt it's concrete cancer which is a term assosciated with Alkali Aggregate Reaction, a serious but mercifully rare condition, and rather normal spalling due to the expansive forces generated by rusting rebar after water has got into cracks in the concrete and done its thing with the steel.

I'd be inclined to clean off loose rust use a proprietry rust treatment and then a repair epoxy

 

[JohnD]

That post is particularly bad. I can't see a leaking gutter above it so the original damage might have been drilling it for the lamp.

I agree, wire brushing, kurust and epoxy repair. I suppose if you blind it with grit you could trowel on a mortar patch afterwards. You can use wooden battens at the sides as forms to give you a straight edge.

Have a look at the interior of the post for soundness.

BTW many liquid rust removers are acidic and will attack concrete. Apply kurust with a small paintbrush to the rust only. It will turn blue when ready.

 

[noseall]

Hi, first time using a forum, so I hope I'm doing this right. I'm looking for advice from anyone who might have experience with this.

I'm a fairly experienced DIYer and up for trying something new. I have a pre-cast garage that I believe was put up in the 1930s. Almost everything is fine with it, but there's one panel with a problem—please see the picture below. One post has deteriorated badly.
I'm not concerned from a structural point of view because everything else is solid and the roof is quite light. I'm just looking for advice on what I can do to repair this.

My thought was to:

• Cut out the rusted rebar
• Tie in a new piece of rebar
• Build shuttering around it
• Pour in concrete to form a replacement section and seal it in

I'm wondering if anyone has any ideas about products that might work better or a more effective approach to this repair.


Many thanks!

There’s actually nothing stopping those concrete panels from being pushed out from inside. Surely you need to bolt a galv steel plate or some such, to the post?

 

[Old Salt]

The post with the other light is going too.

 

[stevie888]

Then the light installation was likely the start of the problem: heavy handed use of an sds started cracks, water penetrated, rust started to form expanding so opening crcks for more water to enter. Get freezing temperatures and ice effects added to mix

 

[sillettx]

Hi, I just wanted to thank everyone for the responses. I really appreciate you taking the time to give me feedback — it’s been invaluable.


We moved into the house 10 years ago. That particular post had already deteriorated from the bottom up when I moved in; it just gradually got worse until the whole thing fell away. I’m fully aware that this post supports the panels, although the panels themselves are absolutely rock-solid and aren’t going anywhere at the moment.

One idea I had was to create a T-shaped support
from a piece of wood, then bolt it into the existing concrete. I’ve also seen a few approaches online where people drill bolts into the existing concrete, wrap wire mesh around it, and then use that as a base for the epoxy repair.


Some great ideas overall — I really appreciate everyone taking the time to share their thoughts and feedback