Concrete patch advice needed.

[ed kerns]

Last fall I had to run a new drain line from my (outside) basement walk out. In the process I had to cut and break out about a 10" swath in the concrete slab for the pipe run. It's time now to patch the slab and I'm looking for advice on the best way to accomplish that. The original slab is about 5" thick. How best to tie the new to the old? Can I just dig in a little deeper so the new pour mushrooms under the original pad a bit? Should I try to tie in with re-rod? Do I need to clean where the new meets the old? What product do you recommend? The full pour will be about 10" wide X 8' long x 6" deep.
Part two of my question is how to best tie a new sidewalk to an existing sidewalk, as I had to break out several feet of walk to run my drain. I'm thinking of drilling re-rod into the end of the existing walk, just to be sure one section doesn't frost heave. Does this make sense, or is there a better way? Thanks!

[mike4244]

Forget the re-bar. Just mix the concrete, pour it in and level it with a piece of 2x4. Depending on the original finish , whether smooth trowel or a broom finish you wait til the concrete begins to set, it will whiten a bit. Then smooth trowel , broom finish or maybe just leave at a wood float finish. You need about four 50 lb bags of Quickcrete. Might take months or longer for the patch to blend in. 
Before you pour, tamp the dirt best you can. This will help to avoid uneven settlement. 
mike

[ed kerns]

Forget the re-bar. Just mix the concrete, pour it in and level it with a piece of 2x4. Depending on the original finish , whether smooth trowel or a broom finish you wait til the concrete begins to set, it will whiten a bit. Then smooth trowel , broom finish or maybe just leave at a wood float finish. You need about four 50 lb bags of Quickcrete. Might take months or longer for the patch to blend in. 
Before you pour, tamp the dirt best you can. This will help to avoid uneven settlement. 
mike

Thanks for the response Mike. I've poured and finished concrete before, but never trying to meet new stuff with old stuff, so my biggest concern is that it all bonds together ok. So you're saying no prep needed to the existing concrete, other than to just rinse it down and be sure it's clean?

[crokett™]

If it were me I would drill for short pieces of rebar in the existing slab assuming you can drill in a 10" wide gap. They only need to protrude from the sides 2" or so. they will act as keys and hold the cured patch flush to the rest of the slab if any of the dirt under it settles.

[ed kerns]

If it were me I would drill for short pieces of rebar in the existing slab assuming you can drill in a 10" wide gap. They only need to protrude from the sides 2" or so.  they will act as keys and hold the cured patch flush to the rest of the slab if any of the dirt under it settles.

Yes.  This was my original thought as well. I'll probably have to drill at a weird angle to get rod in there, but bottom line is I guess it can't hurt. I was thinking about the new patch frost heaving, but but you're probably right that the more likely scenario is it could want to settle. Do you agree that Quikcrete will do the job as opposed to some sort of latex patching compound?

[Roly]

Yes.  This was my original thought as well. I'll probably have to drill at a weird angle to get rod in there, but bottom line is I guess it can't hurt. I was thinking about the new patch frost heaving, but but you're probably right that the more likely scenario is it could want to settle. Do you agree that Quikcrete will do the job as opposed to some sort of latex patching compound?

Quickcrete will work fine,  suggest using a concrete bonding agent brushed on the old concrete, Quickcrete makes one along with other companies.   Clean to old concrete surfaces before applying the bonding agent.  ( prefer the Quickcrete brand as other brands can be iffy )   Roly

[Admiral]

Yes.  This was my original thought as well. I'll probably have to drill at a weird angle to get rod in there . . . . .

Had a similar issue of angle drilling a few years ago, here's a Harbor Freight gem for $30, less with a coupon....  worked for me and still works just fine; good to have one when you need it.  Would be a bit slow drilling into concrete however....

https://www.harborfreight.com/power-tool...60610.html