what is the best way to repair this 2

[delagina]

what is the best way to repair this column?

 

[delagina]

 

[Ron]

According to a couple of recent threads, just encase in epoxy! Wouldn't recommend that approach!!

First, determine cause of delamination. Is it rebar exfoliation/ expansion due to corrosion? Is it freeze-thaw? Is it reactive aggregate?

Once you've determined cause of issue, you can then decide repair method.

Assuming nothing insidious, chip all loose material, dowel into column, prep exposed rebar and gouge behind for keying, provide small rebar cage outside existing, form and place new concrete. Give plenty of clearance for proper placement and embedment. Make sure new concrete is dense and will reduce permeability to protect rebar.

Obviously make sure all ok structurally!

 

[msquared48]

Thank god for confinement steel. I agree with Ron that you need to first determine the cause of the spalling. Then any fix or replacement.

Come on Ron... Epoxy would be great!

Mike McCann
MMC Engineering

 

[bridgebuster]

I agree with Ron and Mike.

You may need shoring. I've done some concrete repairs on bridges that turned out to be more than what they appeared to be at first.

 

[BAretired]

Spirally reinforced columns tend to fail by spalling of the cover. Is the column heavily loaded?

BA

 

[delagina]

column is not heavily loaded. i'm not sure but i guess it's the rebar/ties corrosion causing spalling or maybe because it's spiraled like baretired said. i have a few of these columns but this is the most severe. this is inside an old chemical plant.

 

[msquared48]

"this is inside an old chemical plant."

What chemical?

Mike McCann
MMC Engineering

 

[cvg]

the concrete appears to be in very poor condition, which might be explained by chemical exposure or poor consolidation or ASR? or just lots of water or humidity?
the column is very slender, bending or lateral force could cause the spalling. was there an earthquake? or did a forklift run into it?

 

[msquared48]

Personally, in looking at this closer, I would rather blow it in place.

Mike McCann
MMC Engineering

 

[BAretired]

That would be one idea, Mike...remove all concrete outside the spiral reinforcement, then wrap the thing with wire mesh and use shotcrete properly anchored to the concrete.

BA

 

[hokie66]

First thought is spalling due to porous concrete allowing corrosion of the steel. But it is hard to tell from the photos how much corrosion has occurred. The concrete looks very porous, sort of like concretes I have seen which had beach sand, shells, etc. as aggregate. I think this requires shoring, removal of cover concrete, and enclosing the column including new reinforcement.

 

[paddingtongreen]

With hokie66 but stipulate that the cover mix be carefully selected for the particular chemical environment.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin

 

[dik]

Looks like corrosion... Matter of shoring and careful hydro demolition to remove the concrete for an inch or two beyond the rebar. A cementitious patch should be applied.

Dik

 

[VoyageofDiscovery]

Looks like an aggregate size vs. spiral pitch issue during the original pour, the cover doesn't look like it has much aggregate. If this is the case, repair alone, is not going to cut it. I would look into additionally fiber wrapping this column in its entirety and any other columns that show similar signs of distress.

VoD

 

[NS4U]

what does the concrete inside the cage look like? Is it cracked? Loose? if it is cracked it may give an indication of ASR, DEF, or something similar. If the concrte inside the cage is fine, rebar corrosion may be more likely.

 

[NS4U]

Is the spalling cracking only on side of the column? Seems odd for corrosion, if so.

 

[SLTA]

I was going to recommend thinking about fiber wrapping, too.

 

[dik]

Hydro demolition will likely take care of concrete within the cage... and it may be the entire column gets removed...

Dik

 

[shobroco]

I'm with Dik,& find out what chemicals are in play so the repair can deal with them.