Patching crack in concrete

[Newaryon]

I am very new to home repairs. I've been watching how-to videos on YouTube.
I am trying to repair a crack between my concrete walkway and the house foundation by the front door.
This one shows a method to fix a problem sort of like mine. I started by cleaning out the dirt and broken concrete in the crack. But I find it is much deeper than the one shown in the video. It looks to me like it was formerly filled with some concrete or mortar that has deteriorated over the years. And below those crumbled pieces I find sand. After all the cleaning, I find I have a space that is 5 feet long, 1 inch wide, and 3 inches deep. Are backer rods and pool noodles good enough to stuff a gap that is 3 inches deep? Or do I need to do something to fill part of this up so it is shallower? Gravel, sand, mortar?? And then put the backer rod on top of that? Or should I stack 3 one-inch backer rods on top of each other. And then add sand and sealant on top of that?

 

[PJB12]

I'm not a flat work guy, but 3" is pretty normal for concrete, especially a driveway. Compacted sand is often used under concrete, so no worries there.

I'd check the TDS for whatever patch you choose and pack sand very tightly to leave the depth the patching material dictates. Pack, water, pack, water, etc. until it's well compacted.

Keep in mind that this crack will probably return. Stuff moves, which is how the crack developed.

If you can undercut the crack, the patch will be held better. (Undercutting is taper the edges to make the crack an upside down V shape.) A quick sketch is attached below to try to explain better than my words.

You may prefer to put urethane caulk for masonry instead, such as Vulkem. It won't look great, but will flex.
Or, try a repair with concrete patching like normal and maybe it'll last a while.

I've used auto body fillers on spalls from ice. It lasts for decades. But, use the waterproof type, not every day Bondo. Auto body suppliers have white filler and grey product. It's lighter than concrete, but not glaringly so.

Paul

 

[Steve123]

a crack between my concrete walkway and the house foundation by the front door.

Got a picture ?

Does not sound like a crack. Your foundation and the walkway are separate pours. The walkway will move with the seasons and over time, and with temperature. I wouldn't fill the gap with concrete patch. Probably a better fix would be backer rod and grey polyurethane masonry caulk.
Put down a strip of 2" painters tape on the walkway and foundation before caulking, so you get a couple of nice straight lines.

 

[Snoonyb]

I'm not a flat work guy, but 3" is pretty normal for concrete, especially a driveway. Compacted sand is often used under concrete, so no worries there.

I'd check the TDS for whatever patch you choose and pack sand very tightly to leave the depth the patching material dictates. Pack, water, pack, water, etc. until it's well compacted.

Keep in mind that this crack will probably return. Stuff moves, which is how the crack developed.

If you can undercut the crack, the patch will be held better. (Undercutting is taper the edges to make the crack an upside down V shape.) A quick sketch is attached below to try to explain better than my words.

You may prefer to put urethane caulk for masonry instead, such as Vulkem. It won't look great, but will flex.
Or, try a repair with concrete patching like normal and maybe it'll last a while.

I've used auto body fillers on spalls from ice. It lasts for decades. But, use the waterproof type, not every day Bondo. Auto body suppliers have white filler and grey product. It's lighter than concrete, but not glaringly so.

Paul

I like vulkem, and top with 60 or 90 silica sand to aid in texture and color approx.

 

[PJB12]

I like vulkem, and top with 60 or 90 silica sand to aid in texture and color approx.

If you're interested, they've got a Vulkem now with the silica in it already. It's a little harder to tool & kind of a fine grit, but you pretty much get the texture of mortar. Color match? Not so much.

I like their primer. It seems to ramp up the already tenacious grip of Vulkem, letting it stretch farther. The building maintenance department guys where I worked are who told me of the primer. (Need lots of ventilation when applying it. The VOC is off the chart!)

 

[Snoonyb]

I used it for leaky gasketing on clear-story glazing, on tilt-ups.

 

[PJB12]

A Caulk of Many Uses!
I shouldn't admit this, but I used Vulkem as a gasket sealant on a nitrogen generator and an absorption chiller's ammonia pump (or two, or three...).

That crazy stuff also worked fine to make a gasoline cap gasket for my weed wacking gizmo.

 

[Snoonyb]

YEP, good stuff, little know and not widely advertised.