# filling cracks in concrete, to prevent weed emergence?



## Maintenance 6 (Feb 26, 2008)

Control joints are installed in concrete to allow for movement due to expansion and contraction. This is to prevent heaving or cracking due to pressure against ajoining slabs. Installing a solid material in the joint will defeat it's purpose. Most likely the soft mortar will shatter and blow out in short order, leaving you with the same problem you have, plus clean up. You could install caulking in the joints. Without knowing the size of the joint, I can't tell you if the lineal foot price of caulk will be cheaper than the polymer you are already using. If you caulk, stay away from the homeowner type silicones. They have poor adhesion to masonry. Polyurethane caulks like Sikaflex or Tremco Dymonic work better. There are some newer silicones that are supposed to work well on masonry, but I've not seen any of them in the box stores yet and have not personally tried them. Whatever you use, make sure the concrete surfaces are clean so the material adheres properly, and follow the manufacturer's guidelines for joint size and shape. Most sealants fail because of imroper prep and application, not because of bad materials.


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## joeyboy (Apr 10, 2007)

Good to know!! Wow I can't believe I missed that, I mean I put control joints in the concrete edgers I made all for all my garden beds, can't believe I was thinking to pour mortar in the driveways!!! 

What do you think of doing the soupy mortar in the cracks in the driveway? I've got just plain ole heave cracks in the driveway, any issue with doing the soupy mortar in those? I know it'll likely crack again over time, I guess I'm just thinking that, through the paradigm of weed control, the soupy mortar will do the job 'ok', although surely it'd need supplemental applications every so often. <<<<< to be clear, I guess I'm saying that, on the cracks besides control joints, the heave cracks, it's not worth the $$ to use a proper material, it's easier to just keep pulling weeds out - I'm figuring the soupy mortar would do an 'okay' job with preventing them, maybe just significantly reduce what actually gets through.. certainly not a great solution, but for the time and money it seems efficient, no? >>>>


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## Tscarborough (Mar 31, 2006)

Actually, the joints are there mainly to allow for the shrinkage of the concrete as it cures, that is, to control the cracking. You can get a similar product to the big box junk in bulk at a real supply house but it is still not cheap. It is, however, the correct way to do it.

If you have to go cheap get an asphaltic emulsion type, but be prepared for sticky joints in the heat.


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## Bondo (Dec 8, 2007)

> I've been messing around with ideas, like weed pre-emergent stuff, but far too many lines are bordering garden beds that I can't take any risks of runoff.


Ayuh,....
A light spraying with Clorox a couple times a season will keep the cracks Free of Weeds.......
It dissipates quickly,.. No worry about anything not directly sprayed....


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## justdon (Nov 16, 2005)

I thought that was the purpose of too "OLD" of gas to burn in a lawn mower. Dribble a bit in those once or twice a season and problems all gone.Use a small snozzle and it goes a LONG ways!! DONT even TRY to use older gas in any small motor,problems galore!!


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## js2743 (Feb 13, 2008)

use round up weed and grass killer it only kills what you spray it on and with your problem you might have to use it 2 times a year to kill the weeds and grass.


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## Bondo (Dec 8, 2007)

js2743 said:


> use round up weed and grass killer it only kills what you spray it on and with your problem you might have to use it 2 times a year to kill the weeds and grass.


Ayuh,..... Just like Clorox,......

Difference is,... Round-up is about $80.00 a Gallon.... Bleach is a Buck or 2......


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## joeyboy (Apr 10, 2007)

bleach kills as effectively as roundup/glyophos?


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## DepotDweller (Dec 20, 2007)

joeyboy said:


> I've got weeds growing in all the control joints/lines in my concrete driveway.
> 
> 
> I purchased a product called 'crack filler' to fill this, but at $8/bottle and not even 30 linear feet, I need something else!!!!
> ...


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## DepotDweller (Dec 20, 2007)

js2743 said:


> use round up weed and grass killer it only kills what you spray it on and with your problem you might have to use it 2 times a year to kill the weeds and grass.


 
yeah, what he said.:thumbsup:


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## DepotDweller (Dec 20, 2007)

Another reason to have that roundup available, and another reason it's cost effective to use that, is you'll need it for your landscaping/gardens, etc. I haven't used the landscaping black cloth you lay over the dirt so weeds don't come up in years. It's a pita and a waste of money, not to mention gets messy after so many years and doesn't work well. I spray my gardens with the roundup big time b4 laying the mulch, then don't have to spray again right over the mulch for a good 6 months or so. The heck with the cloth crapola.


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## DepotDweller (Dec 20, 2007)

Bondo said:


> Ayuh,..... Just like Clorox,......
> 
> Difference is,... Round-up is about $80.00 a Gallon.... Bleach is a Buck or 2......


 
I just caught this............where on earth do you live that roundup costs that much? :huh:


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## joeyboy (Apr 10, 2007)

it does - you're thinking of diluted roundup, he's referring to the concentrated glycophosphates. I actually have a good deal left of the concentrated stuff, it's not even a gallon's worth and it was probably aroudn $30, but I know it wasn't the most concentrated available.


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## Tscarborough (Mar 31, 2006)

Keep on poisoning the world. Be sure and use lots of weed and feed and ant killer while you are at it. Don't forget the corkscrew flourescents and the hybrid SUV to assauge your guilt, though.


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## joeyboy (Apr 10, 2007)

could've sworn glyophosphate breaks down to safe metabolites in a relatively short period of time, is that inaccurate? And if that was directly aimed at me, the ant killer I use is orthoboric acid=boric acid=borax, it's insanely safe and nontoxic.


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## justdon (Nov 16, 2005)

*you are so right*

Roundup is rendered enert by contact with ANY dirt or dust. It works on anything green,,,it does NOT kill anything in the future,,NO preemergence!!

Pramitol or other non selective s are actually about the best choice,,if you can controll the run off etc.. Roundup you keep spraying those little weeds time after time,,,they just keep on coming!! Lots of options,,check with a local lawn and garden store. OR try about half or a third of that crack filling stuff,,,it doesnt HAVE to be level you know


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## Tscarborough (Mar 31, 2006)

I was not pointing to you, Joey, just in general. I just wait until it rains and pull up and weeds in the pavers, and weedeat the old joints until I replace the concrete with pavers.

Roundup is a man made chemical, and my trust level with Monsanto, et al is exactly Zero.


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## DepotDweller (Dec 20, 2007)

Tscarborough said:


> Keep on poisoning the world. Be sure and use lots of weed and feed and ant killer while you are at it. Don't forget the corkscrew flourescents and the hybrid SUV to assauge your guilt, though.


well that was productive :whistling2: you've pointed out the problem.......do you not have a solution or do you prefer to live in the problem? Do share an alternative that works please.


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## Tscarborough (Mar 31, 2006)

See post #18.


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