Replies

1. 
   ChrisB | Sep 07, 2005 11:39pm | #1

   As a matter of fact, I just watched a crew do just that on a new construction house basement floor yesterday. They used a gasoline driven saw on wheels. Sort of like lawn mower  except it was a saw. Took about a minute per groove, and each groove was about 60 feet long. There was no water or other lubrication so it was quite dusty.

   I would think you could rent one from a concrete supply shop or an industial tool rental place.

   The blade was  diamond about 16" in diameter.

    

   Chris

2. 
   SamT | Sep 07, 2005 11:41pm | #2

   David,

   For that little cut, just a masonry blade for the power saw.

   Make several shallow cuts, about three or four of 'em 1/4" deep.

   The blade wears away pretty fast, so I'ld make a kerf, readjust for depth, move to the next score line, cut it, then do the last before starting on the first kerf again. When I ran out of blade, I'ld call it good.

   Afterwards, take the saw apart and clean and lube it.

   SamT

3. 
   AdamGreisz | Sep 08, 2005 03:16am | #3

   David, use your beater skillsaw with a masonry blade. I buy the $40 carbides but abrasive work as well. Total score only needs to be about 1  " deep. The rest of the slab will crack under your slab during curing. You can do it wet or dry. Dry makes lots of nasty dust so wear a respirator or dust mask.

   Piece of cake. You probably have already finished the job.

   Wood is Good

   Adam Greisz

    

4. 
   FastEddie | Sep 08, 2005 04:01am | #4

   You could use a diamond blade in an old skilsaw.  Inexpensive ones are about $20 and will last much longer than the same dollar amount of abrasive blades.  You could even use a 4-1/2" grinder with a diamond blade.  Make sure it's plugged into a gfi outlet and let the garden hose drizzle some water on the cut to keep the dust down and the blade cool.

    

    

   "When asked if you can do something, tell'em "Why certainly I can", then get busy and find a way to do it."  T. Roosevelt

1. 
   junkhound | Sep 08, 2005 03:45pm | #11

   Go with the advice FastEddie gave, esp the garden hose part.  Have cut approximately 100 lineal feet 2.5" deep in > 10 YO concrete with cheap 7-1/4" HF diamond blade and it is still going strong.

   I use a double insulated saw. One of the tricks is to keep HIGH pressue on the blade, also, if you only push on the handle,  it tends to wander to the right on a sidewinder, so  use both hands on the saw to prevent twisting.

5. 
   blue_eyed_devil | Sep 08, 2005 04:15am | #5

   I would think that the shringage cracks have already occurred. Two weeks sounds like a long time.

   Walk lightly on that slab!

   blue

    

1. 
   Soultrain | Sep 08, 2005 05:14am | #6

   When I worked in concrete, we always put in the joints during the pour when we did a basement.  For my house, I hired the guy I used to work for & that's how he did mine.

   When my neighbor's house was built, they cut in the joints with a saw later.  I don't understand how this saves any time & it seemed to make an awful lot of dust.

1. 
   blue_eyed_devil | Sep 08, 2005 05:37am | #7

   They all cut them around here now. It produces a better looking end product. But....they always come back the day after the pour to do the sawcutting.

   blue 

1. 
   Soultrain | Sep 08, 2005 05:58am | #8

   I don't know if it's better looking or not.  The saw cuts always stop an inch or two from the end, plus the concrete dust is all over the place. JMO

   Edited 9/7/2005 10:58 pm ET by Soultrain

2. 
   SamT | Sep 08, 2005 01:27pm | #9

   >>It produces a better looking end product.

   Whenever I see a cut I always think someone made a mistake during finishing.

   SamT

6. 
   billmeister | Sep 08, 2005 02:40pm | #10

   Control joints have to be installed within 24 hrs of pouring, except in cold weather.  As mentioned, your shrinkage cracks have probably already appeared, but put some joints in anyway.  I use a skilsaw with a diamond blade, and the cuts should be 1/3 the thickness of the slab.

    

   -Bill