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Cutting concrete slab with a circular saw?

3861 Views 15 Replies 10 Participants Last post by  Yodaman
This might be one of those really dumb questions, but here goes anyway:

I have what can most easily be described as a badly-laid sidewalk-to-nowhere in my back yard. It is 55' long, about 6' wide, and maybe 3" (inches) thick. I need to run some pipes underneath the middle of this thing, and I would like to simply cut a slot (about a foot wide) in this "sidewalk." (I do not care about this concrete cut being pretty, as I eventually plan to get rid of all of it anyway).

My thought: I have an older, inexpensive, 7.5" circular saw. I am contemplating getting a concrete blade for it, and trying (2) cuts about 1.5" deep across the 6' width -- that might give me enough relief to get the remainder of the way through with a sledgehammer. Can I do this? If I have a friend spray a little water around the cutting area, am I creating an electrical hazard?

Actually renting the gas-powered concrete saw (and I have to buy a blade for that) is expensive, and seems a bit extreme for these two smaller cuts (but maybe I am wrong on that).

Appreciate any useful guidance.
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I've done that before. Not 55' but about a total of 10'. I used a diamond blade; it cut like butter. I didn't use water, however.
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Your first statement sounds like you want to cut down the middle of the 55', but then you say across the 6'. Both are possible, but the 55' would take a while :).

I've cut a some concrete and in one case rented a big water cooled saw for an 8" deep cut New blades were $400 back then. I also have an old circular saw and have cut those 2" deep cuts and a diamond blade is awesome. Not sure about needing water, I didn't use it. If they installed rebar the diamond will cut it, but is a pain and I suspect would shorten the life of the blade. Two 6' cuts would be easy. The sledge hammer, not so easy.

Bud
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Go under....don't cut.

Dig a rectangular hole in front of the sidewalk....

Get an 8' piece of 1/2" PVC pipe. Glue a female threaded fitting on one end...glue a cap on the other

With a real small drill bit, drill a bunch of holes in that cap so that it gives you a spray pattern about 4" wide.

Screw the other end to your water hose.

Turn on water and water drill under the slab.

It's messy...but you end up with a nice tunnel.
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Get an 8 foot piece of 3/4" plastic pipe, and glue these two pieces on opposite ends and in about 2/3 minutes you'll be done, just be sure the pipe is laying flat when you start.

http://www.homedepot.com/p/Orbit-Walkway-Tunnel-Kit-53333/100127846?keyword=tunnel+under+walkway
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Your first statement sounds like you want to cut down the middle of the 55', but then you say across the 6'.....
I apologize for any confusion on my part. Ignore the 55' measurement -- I mainly included it for *perspective* regarding this ridiculous piece of concrete. I mean....what does someone do with a 55' x 6' concrete slab in the middle of a fenced backyard? What could someone having been thinking when they poured it?

For the sake of the current discussion, my hope is to make (2) cuts -- each cut being 6' long. If the two cuts are roughly a foot or so apart, that provides the *place* where I hope to break the slab, dig a shallow trench, and lay the pipes. Two cuts -- each about 6' long.....clearer?
Well, maybe I should re-consider.....

Both ddawg and canarywood advocate the "water-jet tunnel-under" approach. While I do eventually want to get rid of that slab little by little, it is certainly not essential to do so right now. The needs of the current task would be met by either a sufficient tunnel or a break in the slab. I will give this some further consideration.

Thanks to all for the helpful replies.
Yes, you can cut concrete with a circular saw; I did it last year; went down about 3-4" for about 6' all told in about 2 passes. I used the Makita blade from Home Depot; tried the cheaper one but the center bit gave out in like a minute. I used a bit of water to keep cut clear; be careful with H2O and electricity.
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A dog run, if they put a fence around it, just a guess.

And, although it would be easy to cut, the water jet for 6' might be even easier. It all depends upon your soil and rock population.

Bud
Well, maybe I should re-consider.....

Both ddawg and canarywood advocate the "water-jet tunnel-under" approach. While I do eventually want to get rid of that slab little by little, it is certainly not essential to do so right now. The needs of the current task would be met by either a sufficient tunnel or a break in the slab. I will give this some further consideration.

Thanks to all for the helpful replies.
I should clarify that HD ad, as they make it sound like each piece is $4.87, they come as a set of two for that price.
I wonder if maybe somebody was going to put in a backyard shuffleboard court? It's about the right dimensions. That or the previously mentioned dog run are probably both pretty good guesses.
What you have is nothing more than a concrete pad below a clothes line.

We had one at the back of our house.....

This is what it looks like after you break it up.

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The needs of the current task would be met by either a sufficient tunnel or a break in the slab.
You don't necessarily cut one tunnel of sufficient size when jetting in multiple pipes. Depending on your soil type, cutting multiple smaller holes may be quicker/easier than one larger one.

While you can enlarge a hole in many "easy digging" soils, in some of the harder soils you can find yourself "size limited" when your water flow/pressure is limited to the garden hose.
What are you running under it? Why not just dig down deep enough k. Both sides, tunnel under as much as you can and pop a pipe through the rest?
I wonder if maybe somebody was going to put in a backyard shuffleboard court? It's about the right dimensions.
There indeed are shuffleboard markings on the pad, although i do not know if such was the original intention. Regardless, the slab is too cracked at this time to allow for decent shuffleboard play.

It is kinda sad in a way: someone must have spent considerable time, energy, and money to install something which I now plan on spending considerable time, energy, and money to remove.
If you go the cut method w/ water use a cord plugged into a gfci protected outlet.
Also a 7" right angle grinder might be a little better choice if available.
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