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Old 11-25-2009, 06:04 PM   #1
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Cracks in cement


I have three A/C units on the right side of my home which sit on a large cement slab. The slab connects to the foundation of the house. There is a crack running from top to bottom at the interface. It's not a large crack but there nonetheless.

Also, I have a crack running horizontally in my driveway for a few feet, where the driveway slopes.

Any recommendations on this? I am thinking it would be good to seal these cracks somehow but I don't know what to use.

Any feedback appreciated.

Chris

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Old 11-25-2009, 06:16 PM   #2
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Cracks in cement


If the driveway is made of asphalt, a crack may be sealed using driveway sealer, cold patch, or hot patch. The concrete crack may be sealed using Thorobond, hydraulic cement, or concrete mix. If it were me, I would not worry about the slab crack, but I would seal the driveway.

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Old 11-25-2009, 06:23 PM   #3
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Cracks in cement


Thanks Daniel! I searched for Thorobond and found it for $25:
http://thoroproducts.net/shop/articl...nd-%C2%AE.html

Lowe's or Home Depot do not appear to carry it so I guess I can order it.
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Old 11-26-2009, 07:41 AM   #4
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Cracks in cement


even asphalt crks ( note local roads ) &, if you follow those directions, won't make much difference other'n appearance.

conc's different - i suspect the crks due to an incorrect jointing pattern/timing/depth, early loading, or unsubstantial base but my $'s on the 1st,,, you can use dan's but that crk may now be a jnt ( meaning movement ),,, ck & see if there's any spall damage,,, if so, proper crk prep & sealing w/100% silicone's better,,, probably can find directions/sketch on dow/corning's w-site,,, t-bond, hydraulic, or conc mix aren't elastomeric & will fail.

dan's bona fides're civil engineer while mine're sawing/sealing contractor for conc/asphalt hgwys, runways, bdge, roads, etc
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Old 11-26-2009, 11:07 AM   #5
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Cracks in cement


Thanks for the reply! It looks like DAP Concrete Repair is a good option at $3.98. I can use it to fill the cracks.

http://www.lowes.com/lowes/lkn?actio...021&lpage=none
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Old 11-27-2009, 06:01 AM   #6
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Cracks in cement


happy you think so but, sure as hell, i don't,,, who said latex was the right choice ? ? ? then again, i already gave you my pro opinion,,, its YOUR ( ) house
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Old 11-27-2009, 10:56 AM   #7
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Cracks in cement


Ok, I should have checked my cabinet. I have a couple options.

100% Silicone:
http://www.lowes.com/lowes/lkn?actio...12A&lpage=none

Conrete Repair (latex):
http://www.quikrete.com/productlines/ConcreteRepair.asp

So you are saying that a silicon product is better to use on a driveway than a product specifically designed for concrete repair?

Chris
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Old 11-27-2009, 11:02 AM   #8
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Cracks in cement


I see the following article:
http://www.doityourself.com/stry/usi...ve-on-concrete

"For real precision jobs, the best adhesive on concrete is a 100% silicone caulk."

As long as it sticks well I can see how it would handle a crack better as it is elastomeric.

It is supposed to reach into the 70s tomorrow and so I will try the (clear) silicon.
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Old 11-27-2009, 11:13 AM   #9
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Cracks in cement


One more thing... How do I get a tiny bead of silicon? I have a silicon gun but the tip needs to be cut large enough for the silicone to pass through which is at least 1/4".

The bead will be much larger than the crack so I was thinking of using a wooden stir stick to push it along. However, I don't want to have a mess of silicon on either side of the crack.

Thanks.
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Old 11-27-2009, 12:41 PM   #10
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Cracks in cement


if you didn't read the section on crk-sealing, http://www.dowcorning.com/content/pu...1015-01.pdfhow do you expect to have it turn out right ? ? ? the crk MUST be ' chas'd ' to provide the proper depth/width sealant ratio,,, typically we saw 'em to 1/2" wide x 3/8" deep then add a bondbreaker tape allowing the silicone to contact & adhere to the crk sides ONLY

http://www.dowcorning.com/content/pu...63-1015-01.pdf - i don't see ' latex ' list'd here NOR do i consider your h/o links worth a ****,,, no pro would,,, here's your mtl - http://www.dowcorning.com/applicatio...EN&DCCSF=269EN,,, what is a ' silicon gun ' ? ? ?

little or nothing worthwhile can be found at an apron store

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Last edited by stadry; 11-28-2009 at 06:57 AM.
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