Caulking Control Cuts

paintguy

Have a concrete driveway (4 years old) and there's a problem: after the rain a lot of sand washing off from the base . The water is going through the control cuts and ruining the base (compacted sand). All cuts cracking on full depth of the slab (4") and sand running with water on the surface of the driveway from the bottom of the slab.
My question to you guys : would it help if I put poly caulk (Vulkem or similar ) to the FULL depth of the cuts? Or should I caulk just upper depth (1/2") using backing rod? What the best way? Cost of the caulk is not an issue.
Thanks in advance.

mdshunk

I used a bunch of Tremco Vaulkem 45 self-leveling around my house for such places. It cost me about 25 bucks per quart tube. Beware that this stuff will "flow" to where ever, so since it's expensive, use backer rod if you think you have the grand canyon underneath any of your control cuts. Otherwise, you'll dump 200 bucks worth of sealant down a little wee cut line. (that's the mistake I started to make).

paintguy

Well, for now I'm worried about losing flexibility if use on full depth vs just upper part.

cleveman

I think MD got it right. Use backer rod and caulk.

I'm surprised to hear that you're cracked all the way through everywhere.

Maybe use a larger aggregate for the base next time as well.

Location?

mdshunk

I guess the question that comes to mind for me is .... why would you want to do that anyhow? That crap's expensive. As far as flexibility goes... it dries like chewing gum. Pretty flexible.

paintguy

Live in Michigan. As for flexibility : if I do just upper part , like 3/8" or 1/2" deep and 3/4" wide, I'm gonna be OK, per manufacturer quote. But same time I want to create GOOD seal from the water backing up on the surface from the bottom of the slab, not just entering from the top, and I'm not sure if 3/8" bead will hold that water.
Your ideas ?

mdshunk

You've got water that will percolate up from underneath under some pressure? Holy smokes. It sure sounds like you're asking the product to perform way outside it's normal specifications. It might work, but I'm certain that's not its intended duty. I'm not so sure you'll find any self leveling control joint sealant rated for such use. Best of luck on that one. The Tremco stuff is the best stuff I know about, so if anything will work, it will be that stuff. Just don't expect to read that it's expressly rated to perform in the manner you'd like it to.

pritch

Just push the backer rod further down-like 2 inches or whatever. That should keep anything from pushing up through. Any quality-brand sealant will bond well enough to the rough sides of the control joint or crack.

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fez-head

We use Sonnoborn NP1 (limestone Color with a sand texture to help blend) but not the SL1 self leveling.

When SL1 self leveling is applied in the mornings the water vapor rising from beneath the warming concrete creates bubbles in the sealant. Not to mention the uneven mess if there is any kind of slope at all.

NP1 on the other hand can be tooled just right, does not "run" or "bubble". I would definately push the backer rod a min. of 1" deep or your joints will tear open sooner.