Leveling concrete apron idea

[Pirate]

The new to us house has a lanai with a 3' wide apron of concrete around it.
The apron on the end of the lanai is 21' long and 3' wide. 3 1/2" thick.
Across the 3' width, it slopes about 1/2"or less. toward the lanai.
It needs to slope away for drainage.

Because of a door threshold, I wouldn't want to raise the level at the building more than 1/2"
If I put a layer of concrete on to reslope it, the new concrete would be 0" thick on the outer edge. Don't thing the thin concrete by the edge would hold up.

Ideas?

I guess best would be to remove it all and re pour at correct slope.
I have a mixer, and a concrete saw. Age and energy not so much!
The lanai walls are aluminum, and there is a trim piece at apron lever, with a lot of caulk on it. Isn't leaking into lanai now, but has standing water against the bottom trim piece.

One idea was to excavate under it and let drop on the outter side, then fill in. It has 2 cracks that are visible across the apron, that are tight, but would open up with digging under it. Not sure how close I could get them back together.

So, once again, Ideas?

[fixtureman]

What about concrete jacking

[David G]

Self leveling cement will feather to a very thin edge. I patched several low spots in a concrete driveway and it has held well for 10 years. It was the only surface overlay product that held up. But it will be grey instead of light concrete, so the entire area needs covered.

[Pirate]

Do you remember the brand you used? Any tips?

David G said:

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Self leveling cement will feather to a very thin edge. I patched several low spots in a concrete driveway and it has held well for 10 years. It was the only surface overlay product that held up. But it will be grey instead of light concrete, so the entire area needs covered.

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[blackhat]

With those numbers, I would look for quotes on grinding.

[David G]

It was certainly the Home Depot special, probably Quikcrete brand. I was pouring over an interior wood floor and had some left over. 5 gallons goes a long ways! And the working time is very limited, about 10 minutes if I remember.

Here is a website with some good suggestions.
http://www.oneprojectcloser.com/self-lev...arge-area/