concrete beam repair
concrete beam repair
(OP)
Hi,
I've got a problem with a small concrete beam, roughly 400mm x 200 mm wide, forming part of the roof support of an underground pump house. The top of the beam is flush with grade elevation. The span is not more than 2.5 meters, with very little real load from the adjacent 1 m wide slab that can only accept foot traffic. There has been considerable water penetration from the adjacent earth and surface dripping and the bottom of the beam has deteriorated with the humidity to the point where the outer clear distance has spalled off and the bars have become exposed and rusted. It has two temporary supports holding the beam up now, but I think that those might not really be necessary; just a safety measaure. I'm not sure, so I will verify the full extent of damage. My question is, provided the exposed bars are still sound, is there a way to replace the concrete lost from the beam, perhaps using epoxy grout formed to replace the original concrete clear cover around the existing bars, or is there some other method I could be looking at? I would imagine that all depends on the present integrity of those rusted tension bars. If necessary, is it possible to replace the bars themselves and if so, how would one go about doing that?
Any advice on the matter is greatly appreciated.
I've got a problem with a small concrete beam, roughly 400mm x 200 mm wide, forming part of the roof support of an underground pump house. The top of the beam is flush with grade elevation. The span is not more than 2.5 meters, with very little real load from the adjacent 1 m wide slab that can only accept foot traffic. There has been considerable water penetration from the adjacent earth and surface dripping and the bottom of the beam has deteriorated with the humidity to the point where the outer clear distance has spalled off and the bars have become exposed and rusted. It has two temporary supports holding the beam up now, but I think that those might not really be necessary; just a safety measaure. I'm not sure, so I will verify the full extent of damage. My question is, provided the exposed bars are still sound, is there a way to replace the concrete lost from the beam, perhaps using epoxy grout formed to replace the original concrete clear cover around the existing bars, or is there some other method I could be looking at? I would imagine that all depends on the present integrity of those rusted tension bars. If necessary, is it possible to replace the bars themselves and if so, how would one go about doing that?
Any advice on the matter is greatly appreciated.
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO, BP
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"Being [b][c






RE: concrete beam repair
Alternatively there are many fibre reinforced polymer sheets/ compounds available. One is Aquawrap. you can read there manul to see how to use.
I tend to stay conventional unless the HIGH cost associated with new product is justified.
RE: concrete beam repair
I would use SikaTop 111 Plus, extended with coarse sand or Sika MonoTop 611, also extended with coarse sand. Both can be flowable and will achieve more than 35MPa
RE: concrete beam repair
DaveAtkins
RE: concrete beam repair
Thanks very much Dave and Ron. I understand clearly what we should be looking to do. Thanks Ron especially for the brand and material designation. I'll have to see if that's available in Spain, or hunt up an equal product.
Another happy customer!
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." [b]Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.co
RE: concrete beam repair
http://www.sika.es/
RE: concrete beam repair
I'll bet that makes one hellova paella.
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." [b]Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.co
RE: concrete beam repair
RE: concrete beam repair
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." [b]Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.live.co
RE: concrete beam repair
RE: concrete beam repair
By the time I got to it, the beam steel was gone and I had to resupport the slab. A couple of years later the problem had continued unseen into the slab and that was that.
RE: concrete beam repair
RE: concrete beam repair
Can the bar be cut back if needed and new bars be field welded in somehow to good portions of the old bars (how do you weld bars together), or should the concrete be cut back enough to expose a proper development length and simply lapped together over that length?
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.liv
RE: concrete beam repair
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.liv
RE: concrete beam repair
It is considered good practice to continue the concrete removal, even if this involves the removal of sound concrete, along the bars until they are essentially free of significant corrosion. Some judgement required here.
For a beam length of 2.5m, it would not take long to remove the bottom section of the beam for it's full length. I would leave any existing bars in place as long as they were properly sand or hydro blasted, even if they had experienced loss of section. Lapping new bars is preferable if you have the required development length and enough space (for slabs this is easy, sometimes beams are too congested).
If you are going to try and weld new bars, you need to determine whether the existing rebar is a weldable grade.
RE: concrete beam repair
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.liv
RE: concrete beam repair
As for the carbon fiber overlay...It works well, but you would need to do a lot of what you're doing already, so not sure its worth the cost in your case.
The SikaTop 111+ has a corrosion inhibitor in it, so no real need to do anything else....just clean the rebar well and make sure you get new material to flow all around it.
Carbonation is probably not the cause of deterioration here. You can check the depth of carbonation by breaking off a piece of the concrete and brushing phenolphthalien on the freshly broken piece. The non-carbonated areas will turn pink/purple. The carbonation will not change color, thus you can see the depth of carbonation. It is usually limited to about 3 to 6mm. There is a RILEM standard for the test.
RE: concrete beam repair
"Technical Guidelines No. 310.1R-2008, Guide for Surface Preparation for the Repair of Deteriorated Concrete resulting from Reinforcing Steel Corrosion"
It is published by the International Concrete Repair Institute.
RE: concrete beam repair
You may find that after this is repaired a new area will start corroding in only a couple of years. Best to find out the root cause and address it in one go.
There are other rehab products that are available from the same companies such as sacrificial anodes that attach to the rebar or coating to protect the concrete surface against further contaminants.
Once you have the full details then you can get the rep from Sika to recommend an optimum and a minimum treatment.
I would recommend against cutting the rebar, just weld a new bar either side.
RE: concrete beam repair
"We have a leadership style that is too directive and doesn't listen sufficiently well. The top of the organisation doesn't listen sufficiently to what the bottom is saying." Tony Hayward CEO BP
http://www.youtube.com/watch?v=hpiIWMWWVco
"Being GREEN isn't easy." Kermit
http://virtualpipeline.spaces.liv