I am looking for comments on how to handle a slumped concrete patio on a house purchased this past summer.
15' x 8' patio set longways against an 8' ell corner of the house. The patio is concrete, and made out of two separate pours. The first pour sits on an unknown base, below grade, and is at least 10 in. thick. The second sits on top of the first pour, and is about 9 in. thick. So, I have at least 19" of concrete on this patio which, at about 200 cubic ft, and at an average of 150 lbs/ft3, comes in at about 15 tons. The patio has no roof, but I have 3.5' overhangs on the house, so that much of the patio is covered, but enough is open that when it rains, a significant amount of water loads the patio.
The patio has one large crack running crosswise at the middle of the pour (perpendicular to the house and the 15' length). The concrete is slumped in towards this crack. Additionally, the slab is slumped back toward the house, so that the slope of the slab is both toward the middle, and toward the house. So, any rain is funneled down the vee crack in the middle, and runs down between the slab and the foundation, enlarging and furthering the slump toward the house. Separation and downdrop against the house is obvious. Also, the siding (white vinyl) sits directly on top of the pour, but has pulled away somewhat by the slumping. (BTW, whoever invented white vinyl
siding should spend eternity fixing the same buckled piece, in sub-zero weather
fix/replace concrete so I can mortar on a nice stone surface at proper grade away from house.
1) If I just top with a leveler and regrade, I would have to remove siding and re-starter it. And though I plan on re-siding the whole house anyway, just leveling the top leaves the problem in place. Like a cavity, the slump will not magically disappear. So I'm not fond of this one. Don't really like the idea of concrete topping anyway.
2) Slab-jack with portland slurry. This one would fix the cavity slump, but is it possible to jack a slab that comes in at 30,000 lbs? I would also have to re-starter the siding for this fix, since the grade would not be lowered, but slightly increased. Any slab-jackers out there?
3) Jack-hammer away top 6 inches or so, stabilize cavity with slurry, re-pour, then top-stone. This is a good fix, maybe the best, but also the most work!
Sorry for the long post, and best to all!