Caulking/Sealing Concrete Expansion Joints

[Bird]

I got a lot of good information, advice, and help with this thread, and I finally got some weather to put it to use. Home Depot only had the backer rod in one size; 3/4" which still did not really fit snug in the crevices.

The first picture is where the 3' wide sidewalk adjoins the driveway. Yesterday afternoon, I put two strands of the backer rod in that crevice, then applied one 10.1 oz. tube of gray Sikaflex SL sealant. It looked good when I finished, but when I went back later, I found that the sealant had leaked down around the backer rod unevenly; not too bad, but not good either. So, this morning, when I did the rest of the job, I added some of the sealant and hope the fresh stuff adheres well to that which was applied 16-17 hours earlier.

The second and third pictures are of the 16' driveway at the garage door apron. Again, I first inserted two strands of the backer rod. Then I added 20-25 pounds of sand and worked it down over, but also around, the backer rod with a wide putty knife. And finally I applied almost all (not quite all) of two 29 oz. tubes of the same sealant. Not as pretty and neat as I'd expect from a professional, but I guess not too bad for an old amateur.

The pictures might have come out better if I'd taken them early, before the sun and shadows showed up.

The fourth picture is a sample of the (hairline?) or larger cracks in several places in the driveway. After wet weather, it seems that some moisture wicks up through those cracks. They're definitely too small to use the Sikaflex on them, but is there a sealant you'd recommend? And the dark, or black, part of the photo is the shadow from the tree behind me.

 

[JB4310]

I got a lot of good information, advice, and help with this thread, and I finally got some weather to put it to use. Home Depot only had the backer rod in one size; 3/4" which still did not really fit snug in the crevices.

The first picture is where the 3' wide sidewalk adjoins the driveway. Yesterday afternoon, I put two strands of the backer rod in that crevice, then applied one 10.1 oz. tube of gray Sikaflex SL sealant. It looked good when I finished, but when I went back later, I found that the sealant had leaked down around the backer rod unevenly; not too bad, but not good either. So, this morning, when I did the rest of the job, I added some of the sealant and hope the fresh stuff adheres well to that which was applied 16-17 hours earlier.

The second and third pictures are of the 16' driveway at the garage door apron. Again, I first inserted two strands of the backer rod. Then I added 20-25 pounds of sand and worked it down over, but also around, the backer rod with a wide putty knife. And finally I applied almost all (not quite all) of two 29 oz. tubes of the same sealant. Not as pretty and neat as I'd expect from a professional, but I guess not too bad for an old amateur.

The pictures might have come out better if I'd taken them early, before the sun and shadows showed up.

The fourth picture is a sample of the (hairline?) or larger cracks in several places in the driveway. After wet weather, it seems that some moisture wicks up through those cracks. They're definitely too small to use the Sikaflex on them, but is there a sealant you'd recommend? And the dark, or black, part of the photo is the shadow from the tree behind me.

Looks OK Bird, it will weather and get dirty so will blend in better.
Once you gun that stuff out, it's beyond your control, so I guess that self leveling stuff isn't any easier to use than the reg tool finished polyurethane, maybe in some regards tougher.

As far as those smaller cracks go, anything you do to them is gonna make them stand out like a sore thumb. They have probably been the same size for a long time and will not likely get any bigger.
If you had to fill them, you could use a clear silicone caulk with just a tiny tip cut, inject it in the crack and clean off the excess, but that stuff is glossy and would attract attention to the cracks, likely looking worse than just the cracks.

JB.

 

[jinman]

Nice job on filling in the grooves, Bird. As John said, almost anything you do to the cracks is gonna stand out. I've seen many repairs using hot tar, but they look very ugly. It keeps the water out so it won't freeze and expand, but it wouldn't be my choice for a driveway. I think I'd be tempted to fill the cracks with fine sand-blasting sand and then squirt in a two-part epoxy from one of those dual mixer tubes. Epoxy adheres very well to concrete and even glass, so it might be just the cure. I think I'd experiment with a small area before doing the whole thing though.

 

[FallbrookFarmer]

I have similar expansion strips in my driveway, I have a plastic U shaped extrusion that sits with the solid side up.
The strips are used for running low voltage wires for driveway lighting, so I don't want to fill them in.
Try a concrete supply company for these, not sure of what they are called, but might do the trick.

 

[tommu56]

I had a brain storm (more like the fog between my ears cleared for a second or two) for the wider cracks use pipe insulation as backer rod.

tom

 

[Bird]

That might be a good idea, Tom.

 

[LarryD]

Bird, try leaving the sealant just a little lower than grade. I think the instructions say this somewhere. As for "sinkers", I always go back within an hour of first application to refill these. The Sikaflex is still fluid enough that added material just blends right in. Sometimes I have to babysit a spot if it still sinks but eventually it stops.

 

[Bird]

As for "sinkers", I always go back within an hour of first application to refill these.

Yep, you're right, Larry. The reason I didn't do that was that I used up one tube of the stuff to begin with; just the right amount, and didn't want to open another tube to use just a little bit. But of course, I should have.