Dealing with rust damaged concrete

evilgoose

I've got a downstairs bay window which is made from reinforced concrete pillars, lintels and sills.

At the bottom of one of the pillers the concrete has been blown (for about 5 inches up the pillar) - the reinfocring rod has rusted and cracked off the concrete. I couple of pieces have completely come off and there are several hairline cracks running for about a further 5 inches up. Whats the best way to deal with this.

Where I can see the rod I have wire brushed it and added some rust inhibitor; my concern is about the rod in the section where the cracks are.

Help! - I cant afford to have the pillar replaced!

thanks

Mikeyorks

Paint the exposed metal with a water resistant paint such as Hammerite. Your choice as to whether you also cut out the cracked area - depends how bad they are.

Then PVA the exposed concrete - and apply a concrete patching kit ** that will dry the same colour as the existing. Apply the final coat with a float and 'polish' it lightly (with the float) to get a good finish.

When all is dry and the patch is as integrated as you can get it - apply several coats of clear silicone to all the concrete where there is likely to be metal inside. All the rods will have started to go - as the concrete absorbs damp. The silicone will largely prevent the absorption.

** eg the Epoxyset at the top of this link. Or try B&Q for similar?
http://www.toolstation.com/index.html?code=46209

stumpjumper

The concrete is being affected by a chemical reaction that is causing corrosion of the re-bar from the inside. The above temporary fixes may work for now, but the only long-term solution is replacing the pillar as the corrosion and cracking will not stop. There are tests that can be done to find out what's wrong with the concrete, but these will cost you more than the building work IMO, and then you may find that you still need to replace the pillar. Concrete testing is what I do for a living BTW.

flang

remember to fill all the cracks otherwise water will penetrate into making it worse!!