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RE: Hollow Core Precast Plank Repair?

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Title: Hollow Core Precast Plank Repair?
The system could also be strengthened using carbon fiber or fiber glass strips such as Sika's Carbodur or similar product.  Typically these are design/build specialty repairs that should be done be an experienced installer.  The manufacturer will be more than happy to help locate a local repair agent and can also provide design services/recommendations.  The concrete would have to be repaired enough to provide a sound substrate to bond to.  The benefits are very low weight added/high strength gain/usually non-reactive with environment.  Downsides are possible complications in fireproofing (the epoxy softens at relatively low temps and can also release very toxic gasses as it melts/vaporizes) and cost.  Last time I looked none of the companies had an approved intumescent material for overhead use.
 
 
Nicholas Blackburn
-----Original Message-----
From: vicpeng [mailto:vicpeng(--nospam--at)sprint.ca]
Sent: Friday, December 14, 2001 8:28 AM
To: seaint(--nospam--at)seaint.org
Subject: Re: Hollow Core Precast Plank Repair?

One repair (to a mechanically damaged slab system, not deteriorated) we did in New Zealand was to use the hollow cores for tensioning cables and anchors to make up the inadequacy.
 
If the slabs are seriously deteriorated, you may have to remove the surfacing, repair the damaged parts (maybe as above), and re-surface.  If you have to do it during working hours, you can possibly stage the repair?

Thor A Tandy P.Eng
Victoria BC
Canada
e-mail: vicpeng(--nospam--at)sprint.ca
----- Original Message -----
Sent: Friday, December 14, 2001 7:42 AM
Subject: Hollow Core Precast Plank Repair?

Does anyone have any experience repairing deteriorated hollow core precast planks? I have a client who processes apples and has been doing so in a building built sometime in the 60's. The building is a steel frame with columns and beams on about 20 foot bays (of course, there  are no drawings). There are two floors. The roof and the second floor are (8" thick for the floor and 6" for the roof) hollow core precast planks. The second floor has a 6" concrete topping with an epoxy coating. The topping has numerous cracks in it which allow wash down water to penetrate the hollow cores. Over the years the water has found it's way to the rebar in the hollow core precast planks - it has rusted and spalled out the bottom of many of the planks. Some have deteriorated to the point that the whole bottom portion of the plank has fallen. My client wants to fix the situation. We have stopped the water infiltration by filling the floor cracks with the appropriate joint filler, but I have not been able to find any information concerning a viable way to repair these planks. I have recommended repair or replacement, but it has been estimated that to replace them will take about 1.5 million. Obviously, if we can devise a repair that is cheaper and will last, they would prefer to do so.

Any information that is available on repair of hollow core concrete planks would be greatly appreciated. Thanks.