Concrete slab and I need to remove two inches by three inches off of a corner

[siligut]

The slab is about two and one half inches thick. I have chiseled away at the edge, it has rocks mixed in the biggest being a little less than an inch.

I do not want to crack the whole slab, obviously, this is a hazard I am trying to avoid by requesting advice.

So far I have hydrochloric acid and a chisel. Is there a known and sure way to do this?

[Hassin Bin Sober]

1. You need to score the concrete so it will break where you need it to break.

I would use an angle grinder with a diamond blade - but you probably don't have that tool.

Another option in a masonry blade in a circular saw.

[Warpy]

2. ...both of which can be rented in most cities.

you just have to pay a deposit equal to the replacement cost of the tool, then you get most of it back when you return it.

That's what I do when I need some kind of tool I don't have and don't want cluttering up this tiny house.

[siligut]

4. Yes, this is a good idea

I was hoping I could manage without another tool, but renting just the right tool is a great idea, thanks.

[siligut]

3. Correct. All I have is a chop saw, though it has served me well

But of course, it isn't going to work for this. As Warpy says, I can rent what I need.

I will look into these options, thank you.

[Wash. state Desk Jet]

5. At tool rentals

You can rent a concrete saw. It will do a perfect cut. You can also hire a concrete guy to do the cut and no more. I suggest you call a tool rental place and ask about availability of concrete saws. That's your best bet and you will get a perfect cut.

[siligut]

6. Yes, we have a good rental place we have used

Aurora Rents will have what I need. http://www.aurorarents.com/?gclid=CLbv_O6-m7YCFYdxQgodZVcArg

I am going to look at the tools. I realize now that just because the size of the piece that I have to remove is small, it doesn't mean that it will be any easier.

I do want a perfect cut. Thank you.

[Hassin Bin Sober]

7. Using a big gas powered saw for such a small cut is going to be a pain in the arse.

I have bad memories of using those things way back when I did concrete work. They are always hard to start (like a chain saw).

You might be able to pick up a circular saw and blade for not a whole lot more than the rental fee. Home Depot has Ryobi for like 40 bucks. You don't need anything fancy for a blade - 5 or 6 bucks should do it.

And you will have a saw out of the deal.

Since the cut is so small and the concrete not thick a circular saw would do it. One or two passes down to about an inch or half and give it a tap with a hammer. Viola!

Just a thought.

[siligut]

8. Yes, now that I know what to look for

Rental fees can be almost as much as buying on some things. I did look at concrete saws on-line and I really don't want to go there if I can avoid it. I am a small person.

I have seen old handheld circular saws at the thrift-shop for around $20. Then I could buy a blade, I gather a diamond blade is best, but could I use any old blade if I didn't care what happened to it?

I will be cheap about it if I can, but I can also envision the saw being whipped out of my hands and into the air to land who knows where.

I was looking at angler grinders on-line and that would probably be my favored way to go. I just have to imagine what else I can use it for to justify buying one.

I am going to have to look and compare my options. I sure appreciate all of the good advice.

[Hassin Bin Sober]

10. Angle grinders come in really handy for tile work.

That seems like the way to go. Home Depot has a 4.5 inch Skill that should work.




Re masonry blade for circ saw:

Something like this :

http://www.homedepot.com/p/DEWALT-7-in-x-1-8-in-Masonry-Abrasive-Saw-Blade-Bulk-DW3521/202579871#.UVJH72oo4c8

[siligut]

12. Even the one star review for that blade is reassuring, as I have so little cutting to do.

I prefer small, light tools. As originally stated, I was using hydrochloric acid and a chisel with good effect, but for the finish I need a clean cut and a saw of some sort will be the best bet.

This is going to be so much easier all around, thank you.

[Wash. state Desk Jet]

9. tool rental stores

Last edited Tue Mar 26, 2013, 08:56 PM - Edit history (2)

Hertz tool rentals has concrete saws for rent=they simply require you leave a open check or put it on a credit card. And Handy Andy also on Aurora 96'th.0r 98th.N in there somewhere. Handy Andy's tools are older but their prices are right. And there is a Hertz Tool rental on Leary way not too far down from Fred Myers on Leary.

The concrete saw is the way to go.
they will tell you how to operate it at the tool rental store. Also Home Depot tool rentals rents concrete saws. HD is on Aurora too a little further N. from Handy Andy tool rentals.

It most likely won't cost more than $40.00 or $50.00 or so to rent the saw for 4 hours.And you won't risk cracking the concrete that way- the other thing about breaking concrete is chasing cracks- Although it was years ago for me when learning forms and foundations-it is easy to bust concrete-but chasing cracks and fixing the damage is a royal pain in the butt.

Get over to Handy Andy tool rentals on Aurora- they sell concrete by the yard- they mix it there and provide the means to haul it. Talk to one of the guys at Handy Andy that knows concrete.

i have never tried a skillsaw with a diamond blade on concrete cuts myself- but guys I know that have say stay away from that-or don't do it. -1. is you burn out the skill saw ! and the other is - iI won't go into that ! I have used a diamond blade on a grinder to clean out cracks that formed as a result of using the sledge hammer. ! The concrete contractor I worked for at that time who was teaching me foundations went out and bought himself a concrete saw after that mess. !

Talk to the guys at Hand Andy Tool Rentals -

[siligut]

11. Yes, it is a dilemma for me

I appreciate the right tool for the job and efficiency. I know a little about cracked concrete and want to avoid that too.

So you prefer Handy Andy to Aurora Rents? I am going to have to get Mr gut to go with me if I go to a different place to rent.

Seriously, the advantage of asking these sorts of questions on-line is that I don't have to see the eye rolls.

[Wash. state Desk Jet]

13. Here is the thing-

Last edited Tue Mar 26, 2013, 11:41 PM - Edit history (1)

Handy Andy tool rentals mixes and sells concrete so there is somebody there that knows about concrete and can advise to to the best way about getting the job done. You don't even have to go there-you can call-inquire about concrete saws and explain the problem. Also Salmon Bay -you can call them too- you've seen their cement trucks all over town.

It doesn't matter where you rent the saw-what matters is that you understand what is involved.
There is nothing wrong with seeking advice- the fact that you are willing to do the work yourself says a lot about you in a positive way. Asking questions is good thing.

Is the depth of the entire slab 2 1/2 inch's do you know or is it really 4" ?

Here is my point- you can break it out, but as rule when you do that you will be doing concrete repair- patch work. If you do a smooth cut-after you remove the cut away parts ,you are finished.
You will not have to worry about cracks or mixing up some sack crete 60-80 lb. bags to finish it off at the end.

What the heck take a picture of it and take that with ya when you go in for a consult.
There is nothing at all wrong about asking around about the best way to get your project done right.


I run into a lot of people that would much rather pay somebody to do it because it is soo much easier that way.

I always admired people that are not afraid to get their hands in there and do the work.

Maybe they will suggest you score it and break it away-but I tend to think cutting is the way go.Most slabs are 4" in depth at least.

And one more thing-down the safety avenues-if you don't have a lot of experience using a skill saw- you really don't want to attach a diamond blade onto that saw than just have at at. There is one hell of a difference cutting into concrete -way different than cutting ply or 2"4"'s or 6's 8's whatever in wood. The saw travels and you really have to know how to operate that saw. And the blade guard,concrete is not the place to start getting your experience with a skill saw.

Good luck with your project-
Let us know what method you go with.
There is pm on here if you are worried about those you think might be rolling their eye back .But I don't think anybody is doing that,-people are here to help.
And for what concrete cost's to have it done these days-you are wise to take all things into consideration before you start your project.

Almost forgot what I wanted to ask ! What is the reason for removing a 2' by 3" piece off a corner ?

[siligut]

14. I am building a new crawl-space door and thus altering the entrance size

When the patio concrete was poured it was blocked off around one side of the crawl-space entrance. The crawl-space is a thorn in my side. None of the guys seem to mind, but I do, so I am going to fix it. Part of the fixing involves a new door. For this I need to make a new frame and for it to be sturdy while not narrowing the entrance, it will extend out beyond the current one.

I do appreciate your "Here's the thing . . .", seriously if we could just know that aspect of any issue we would be a whole lot better prepared for what is to follow.

I measured the edge I am concerned with and it is two and one half inches. I don't know the depth of the rest of the slab, though it does appear about four inches on the opposite side, we are on a slope, so it seems some of the leveling was done with concrete.

It will probably be of benefit for me to check-out Handy Andy. We may be doing more with cement in the future. Mr gut is building a retaining wall in the spare time he doesn't have and so far he is planning to use bricks. I would prefer cement, for the cost, the aesthetics and for the creativity it allows.

As I have stated I am small and large power tools are not the best idea for me, unless they are stationary. I did etch off the part I want to remove with the hydrochloric acid, but the small stones are the concern for which I need a cutting tool. This is where I run the risk of cracks if I try to break it and as you say, I just don't want to do that.

I have only had a bit of trouble with the eye-rolling at Home Depot and Dunn Lumber, it is actually more of a "leave this to us men little lady" sort of attitude. I have never had a problem here on DU, chauvinism seems most often a RW problem.

[Wash. state Desk Jet]

15. combination of things with that issue but RW about sums it up !

I think you are on the right track and I think talking to the tool rental people will be most beneficial for you. The solution may be more simple than I think. But it is always best to check it out. The other cool thing about talking to the people at the tool rental place is that you can look around at all the cool time saving tools that you can simply rent for future projects !

Let us know how things progress.

[siligut]

16. The masonry blade isn't going to work

I found a second-hand circular saw for $13.99 and the masonry blade cost less than $4.00. Unfortunately, using the masonry blade is slow, tedious, spark producing and I believe ultimately I will not be able to finish the job using it. I am going to try a different blade with this handheld saw before I decide to rent a concrete saw.

I have other projects and responsibilities and the going is slow, but I will let you know as I go.

[Wash. state Desk Jet]

17. I know what you mean.

OK, well if you are going to continue with that I used to use my old tile saw to cut bricks every so now and again. cinder blocks and so fourth.

Home depot carry's those tile blades 7 1/4 inch. Should cost about $10.00 there abouts.

That might do it.

If you can score it deep enough -you may be be able to break it with your hammer without running the risk of a crack running wild.

I am only suggesting this because you indicated the area you are cutting is the concrete run off.
You discovered on the other end where the ground is more or less level that the slab is most likely 4 inch's in depth.

Where it tappers down to 2 inch's is what is called the run off in concrete terms.

Good luck and be careful with that skill saw. If somebody is with you when doing the cut- a can of wd40 spraying where you are cutting in front of the blade will reduce the sparks flying somewhat. You don't want to use water around your sidewinder- skill saw.

And of course let me know how it goes. !

[siligut]

18. Thank you for supplying the correct term

Now I know what to call the run off if I need to rent or discuss it when buying the new blade.

I would have thought WD40 was flammable from the way it smells, thanks for the tip.

The sparks and the heat were just too much for the amount of cutting the masonry blade actually did, more like abrading really.

I am careful and cautious and will up date as I go.

[Wash. state Desk Jet]

19. oops on that one

on the wd40 says on the can contents flammable! Something non flammable to reduce the sparks might help. Although I don't think there is a lot you can do to prevent those sparks from flying on those dry cuts.

I shouldn't have suggested wd40 -the idea of something to help reduce the sparks flying popped to mind. Water and electricity don't mix either.

OK so don't use wd40 On the back of the can top it says don't use near sparks or flames.
Wasn't that a dumb suggestion !


well, if somebody is there with you when you go into the cutting, perhaps you can make a shield of some type or other to help block the sparks. somebody would have to hold the shield in place.

A diamond tile blade will give you a better cut .

[siligut]

20. No worries

I was only complaining about the amount of sparking relative to the progress. The masonry blade pretty much just rapidly "sands" a narrow strip. I wear old clothes, gloves, a mask and eye protection, I'm good, but thanks

[Hassin Bin Sober]

21. You can use a spray bottle to wet the concrete down a little.

To be EXTRA safe, plug the saw in to a GFI outlet either in your kitchen, garage or basement. Most kitchens SHOULD have GFI outlets - you know, the square outlets with the test buttons.

You should be plugged in to a GFI regardless - remember, when you work outside you are probably grounded and could be the path of least resistance of a short to the ground. This is why codes require GFIs in basements and outside.

Here's the thing: cutting concrete is a nasty, loud, sparky and dusty endeavor. I was reminded of this last week using my angle grinder with diamond blade to cut some 1 and a half inch thick granite for a friend.

At first I was like "Jesus, this is going to take forever" but once I got my technique down it went fast.

You need to concentrate on one spot and get a "bite" or indentation in the concrete and work out from there. It seems once you get the bite, the saw blade cuts better when is engaged in a smaller surface area.

For me, getting the bite and drawing the saw BACKWARD works best for me. The saw naturally wants to pull forward due to the blade spinning forward. Start about a foot or so forward, getting the "bite"then draw the saw back to even out he level - then repeat.

The concrete saw, if you go that route, will be the same. If all you do is make light passes back and forth you will just polish the concrete.

Using a skill/circular saw, I would probably set the blade guard to about a half inch or maybe a little more, hold the spinning blade in one spot till it digs in and then proceed forward (or backward in my case) to cut across the concrete to the end. Repeat by increasing the depth for each pass until complete.

I'm going to be doing some granite work this weekend helping a friend. We purchased some granite remnants and will attempt to make a few tops for a vanity and laundry sink. I purchased a variable speed wet grinder and diamond polishing pads. I have a single speed grinder but polishing requires a slower/variable speed. I will be working with water and electricity BUT the grinder comes with a built in GFI.

Wish me luck. And good luck to you.

[siligut]

22. Good luck to you, sounds rewarding

Granite is upscale attractive, trendy but classic and tends to make the whole area look newer.

We have a GFCI outlet in a bathroom that is close enough if I use the long cord. I wrap-up and wear face protection so the sparks are OK as long as I feel I am making progress.

Looking at the angle saws made me swoon. Lowe's had one for around $30 that the guy helping me said was pretty good and then one for a little over $60 that he thought was great and a deal. I just can't justify buying one for this little job and don't plan on doing tile work.

I did adjust the height of the blade, thinking I could make a trough for the hydrochloric acid, which would soften the concrete for future cuts, but since I will use the saw and blade for more work I can justify buying a diamond blade. Depending on how effective that is, I may use the trough method, rinsing well in between of course, though the concrete does tend to neutralize the acid.

I will try your method of working backward, though my upper-body strength leaves much to be desired.

[madokie]

23. Being an old concrete finisher who has dealth with this many times

I'd say you have given good advice. If its just cutting a 2 inch by 3 inch off the corner, diagonally then it might pay to buy a cheap skilsaw and a concrete cutting blade and once they're finished with this project they'll still have the saw for other projects. A cheap power hand saw, (skilsaw) can be bought for less than 50 buck and a blade for less than 10 bucks. That would be cheaper than renting a cut saw I would think. Around here a cheap power hand saw runs around 35 bucks, might even get one from a pawn shop for way less than that. I have to add that I personally won't buy from a pawn shop because I'd be afraid that what I bought was stolen property and I don't want any part of that. I know it pisses me right the fuck off when I have something stolen from me. Hard to know for sure so I don't darken their doors.

[Wash. state Desk Jet]

24. Thanks, !

and yes those damn thieves .A tool turns up missing and it feels like a part of ya has been robbed.

I must say I have been lucky over the years having had good helpers that helped to keep track of my tools.

As the saying goes you need the right tool for each thing that you do. And finding ways around not having the right tool is far too time consuming where time is money.
When you buy a tool you invest in yourself and your work.

I hate thieves.
It takes years of hard work to get those tools that are required.