Concrete Patching

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physis

physis

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This might seem a bit off track but I need to dig a trench to run power under a residential drive for an electric gate. My question could easily be answered by the AHJ but for some reason it's not responsive.

So the question is: can I just replace the cut out concrete to the existing depth? Does there have to be rebar? Should there be some means of insuring a solid connection between the two now severed ends of the drive?

[ August 11, 2004, 07:03 PM: Message edited by: physis ]
 
Re: Concrete Patching

Don't think this is a code question or even one for the AHJ and that's why you haven't got an answer from him.

How you patch it is up to you. Most important I would let the backfill settle for at least a month to be sure it will settle no further. Water helps. If the cut is only a couple of inches wide fill it with a concrete and gravel aggregate mix and screed it level with the adjoining sections and finish after it sets up a little to match the rest of the concrete. If it is wider put an inch or so of well compacted gravel in first. In either case the concrete should be equal or thicker than the original. No, you don't need rebar.

Next time consider boring under the drive and save yourself a lot of trouble! :)

-Hal
 
Re: Concrete Patching

I have'nt actually asked the AHJ yet. The trouble with them is that the inspectors are never available to take a call nor do they return calls from messages. But I'm just wondering since you can't pour a slab without an inspection maybe they'ld have a concern about how this drive is repaired.

As far as going under the drive I'd rather do that, it has'nt been cut yet. Can I do this and also satify the inspector that the run meets table 300.5
 
Re: Concrete Patching

...But I'm just wondering since you can't pour a slab without an inspection

How the heck wide is your cut?? I would hardly call that a "slab".

As for boring, why wouldn't it meet code? If necessary sleeve it in RMC under the concrete. I hope you are not considering cutting the drive just so that the inspector can see the wire in the trench! :roll:

-Hal
 
Re: Concrete Patching

Actually, maybe I am being stupid, but that's exactly right. Do inspectors in your area allow you to bury plumbing and electrical without inspection?
 
Re: Concrete Patching

Here, how you patch a residential driveway is up to you.
On interior bldg slabs, our department requires rebar dowels on cuts wider than 12inches to prevent settling or uplift. Do they have a code reference - don't know.
You could apply the same principal to your repair if you wanted to get in and out quick without waiting. Of course if it's a narrow cut you won't get the rotohammer in there.
 
Re: Concrete Patching

The reason this dumb drive is a concern is because the general contractor running this building has caused a particular inspector to assign himself exclusively to this permit because he (the GC) keeps trying to get away with things. This inspector will be using an extra fine tooth comb on this place. I don't want this kind of reputation, I simply want it done correctly the first time and to be ohnest, I'm not sure about the concrete repair or going under the drive. I admit it.

Larry, thank you, I'm in San Mateo county by the way. The concrete repair seems clear, how bout the under the drive method and 300.5?
 
Re: Concrete Patching

Really, I just got off the phone with the AHJ and she said she had never heard of the practice and she is going to make me cut it? Huh!!

Editted this in: I sure don't want to ruin this drive if it's not necessary.

[ August 13, 2004, 11:39 AM: Message edited by: physis ]
 
Re: Concrete Patching

You guys are the best!

I just talked to the AHJ again and told her I was talking to some big shot inspector in Irvine (just kidding) and mentioned Mike Holt's web site (she didn't like that much), she put me on hold, came back and apologized for telling me I can't bore.

Thank you both Hal & Larry
 
Re: Concrete Patching

I agree with these guys, find a sprinkler contractor who has a machine that will bore under the drive, even if you had to hand dig the sides it still is way better than cutting and patching concrete. I have had a bore of 45 feet under a drive, it took the contractor about 30 minutes. It cost me $100.00, he told me he could go as much as 100 foot. I would try anything before I saw cut concrete.
 
Re: Concrete Patching

I bored under driveways with a home made rig. hose to 3/4 copper, ram jet pressure washer. added a section as I went; 30'. not hard at all.

need straight shot access with a trench. if one side has small hill it is easier to bore to a trench on up hill side. big issue is type of ground, rocks, etc. if extremely rocky soil it is probably not possible.

i have a big old spade bit on a shaft for sidewalks. just use the holehawg, works fine.

don't forget to get pvc end cap (water supply style) before trying to push pvc thru.

you could use rigid and pipe would be in place at end of bore. drill large hole in end cap (need to protect threads - remove when done) for pressure. add sections as you go. more work taking the hose and valve off each time, but can use smaller sectons, smaller trench, etc..

to bore: use a repetative pendulum style motion in direction of desired location. aim is important. adjust water pressure for minimum mess, but necessary force to evacuate soil from entire length of hole. if you don't have the arm strength for this, rig a saw horse over the entrance point and run a loop of solid to bottom of trench and ram the pipe from the valve end.

wasn' hard at all, the times i did it. out of that end of business now. good luck.

paul
 
Re: Concrete Patching

Yeap: I leaned this some years ago from a friend of mine doing this on his property. A little more work than you're suggesting but it does work pretty well. And it does make a mess. An intrinsic bonus is that the conduit is self cleaning. I am a bit concerned by the void it leaves though.

I haven't yet decided how to do this one. I have a property line with a fence about a foot and half away on one side and a slab intersected to the foundation on the other. I'm probably going to use a worn out auger and a series of extensions.

Edit: Oh. I didn't notice the pressure washer. My experience is with only street pressure and a fitting on the end of the conduit. Tim Taylor would definately approve of this method.

[ August 14, 2004, 03:25 PM: Message edited by: physis ]
 
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