Underside repair of 30" thick concrete slab in old winery
Underside repair of 30" thick concrete slab in old winery
(OP)
I have a condition in an old winery where the 30" thick slab is failing. The construction dates from 1872. The slab supports large tanks and vessels. The slab is essentially falling away from below. There is very minimal (1 per slab bay) reinforcing bars. Wondering if anyone has a creative way to support or repair the slab from below? My thoughts are to clean and shotcrete from below, or full demolition and replacement - either with precast plank or new cast-in-place slab. See photo attached. Note, it appears the slab may have been placed in two separate lifts.






RE: Underside repair of 30" thick concrete slab in old winery
There appears to be steel beams embedded in the concrete. Are they the structural supports? What kind of shape are they in?
You're on the right track for the fix with shotcrete or some troweled on repair mortar. But I'd figure out the existing system and the problems before I did anything else.
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
If built in 1872, this would have been one of the first reinforced concrete stuctures in existence.
RE: Underside repair of 30" thick concrete slab in old winery
Add, "in the modern era." to the above quotation to make it truthful. Types of concrete have been reinforced with bamboo for a very long time.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Underside repair of 30" thick concrete slab in old winery
Could also be a primitive form of a sandwich panel, concrete top and bottom with a lighter infill material?
All the steel looks rusted, so I question the humidity/leaks/chemicals causing it. Needs to be addressed and solved before any repairs as mentioned above.
Welding a rebar grid to the bottom and shotcreeting could work if the co0ncrete mass is viable. Any cylinder core tests done?
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
Mike Halloran
Pembroke Pines, FL, USA
RE: Underside repair of 30" thick concrete slab in old winery
Dik
RE: Underside repair of 30" thick concrete slab in old winery
RE: Underside repair of 30" thick concrete slab in old winery
Meaning, if the steel beams are deflecting more, this will easily increase stresses in the tension edge of the concrete- creating microcracks and eventually leading to spall.
I think the suggestion to remove the spalling material is a good one. It removes an apparent dead load with no benefit to overall capacity of the floor system.
If overloading is contributing to the issue, deflection of the steel should be measurable.
I'm guessing the area beneath the slab is used for wine storage, in which case they likely maintain 40 or 50% humidity. If so, you may want to propose a solution that will protect the underside from future moisture damage.
RE: Underside repair of 30" thick concrete slab in old winery
Have you considered mud-jacking - a relatively cheap solution to many of these types of problems. Just find a guy who has been doing it about 30 years to guide you..