repairing a missing chunk of concrete

[Homerboy]

There's been a chunk of concrete out of my 80 year old garage slab since I moved in 20+ years ago. It's grown and grown and I just never bothered with it (always something more pressing to take care of). This year though I'd like to get it fixed up before the WI winter hits. The chunk is as pictured below, about 1-1.5" deep

Obviously cleaning out all the loose gravel and dirt as much as possible but then what? Just a simple back of quick-crete and fill it in/level it off? What do I need to know?

 

[Dranoche]

Ideally you would square up and sawcut out the damaged area, dowel in along the bonding surfaces, and re-pour. Or you can just clean it up well before filling. Remove any loose and fractured pieces like those at the top of the photo and remove material that has collected in the hole. Clean any bonding surfaces (wire brush is fine), chip away any loose pieces, blow off any dust. If there's a gap between the two slab sections you may want to use an expansion joint strip so that the new concrete isn't directly against the adjacent slab. If both slab sections are tight together and don't appear to be buckling at all or experiencing spalling then I wouldn't worry about it. Fill it with concrete mix from Lowes or Home Depot. Pay attention to the mixing ratio. If you mix it by looks you'll end up with too much water and the hardened concrete will be weak and will probably exhibit dusting and eventually scaling. Properly mixed it will look dry at first, like there isn't enough water to hydrate all of the cement. Keep mixing and it will reach the right consistency.

 

[Homerboy]

Ideally you would square up and sawcut out the damaged area, dowel in along the bonding surfaces, and re-pour. Or you can just clean it up well before filling. Remove any loose and fractured pieces like those at the top of the photo and remove material that has collected in the hole. Clean any bonding surfaces (wire brush is fine), chip away any loose pieces, blow off any dust. If there's a gap between the two slab sections you may want to use an expansion joint strip so that the new concrete isn't directly against the adjacent slab. If both slab sections are tight together and don't appear to be buckling at all or experiencing spalling then I wouldn't worry about it. Fill it with concrete mix from Lowes or Home Depot. Pay attention to the mixing ratio. If you mix it by looks you'll end up with too much water and the hardened concrete will be weak and will probably exhibit dusting and eventually scaling. Properly mixed it will look dry at first, like there isn't enough water to hydrate all of the cement. Keep mixing and it will reach the right consistency.

Thanks! Yeah - I'm not looking to do this "perfectly" with squaring it up, putting in dowels etc. Just something that won't fall apart after 1 winter. I figured just a good and complete clearing/cleaning and putting in the expansion strip should do the job well enough. Is there a specific mix I should be getting and/or avoiding?

 

[Dranoche]

I would use the standard high-strength mix, less than $5 for an 80 lb bag, about 0.6 cu ft per bag.

 

[Homerboy]

Finally got around to knocking this out (on a gorgeous 60* autumn day too!)
Good for another 80 years? Probably not, but better than the gaping hole that's been there for 20+
My kid put on the finishing touches.

 

[deadlyapp]

Finally got around to knocking this out (on a gorgeous 60* autumn day too!)
Good for another 80 years? Probably not, but better than the gaping hole that's been there for 20+
My kid put on the finishing touches.

View attachment 52504

Not bad, Probably could have troweled or floated it a bit more as it dried to get a better finish but it certainly works fine. You could always chip a little bit away from the edge where the two are bonded and just put a concrete sealant to prevent water from seeping through and frost heaving your freshly repaired section.

 

[Homerboy]

Not bad, Probably could have troweled or floated it a bit more as it dried to get a better finish but it certainly works fine. You could always chip a little bit away from the edge where the two are bonded and just put a concrete sealant to prevent water from seeping through and frost heaving your freshly repaired section.

Yeah I did float it a little. There's so much aggregate that it was pretty hard to get "smooth", But in reality I don't care all that much about appearances. The surrounding concrete looks like crap too I've tried sealants on hairline cracks in my driveway and they never seem to last. even the slightest movement of the slab causes them to crack/tear themselves. I keep trying though!

 

[killster1]

Yeah I did float it a little. There's so much aggregate that it was pretty hard to get "smooth", But in reality I don't care all that much about appearances. The surrounding concrete looks like crap too I've tried sealants on hairline cracks in my driveway and they never seem to last. even the slightest movement of the slab causes them to crack/tear themselves. I keep trying though!

looks good to me (considering what it looked like before (( a broken ankle)) )

 

[BoomerD]

looks good to me (considering what it looked like before (( a broken ankle)) )

Better than before...yes, but me, I would have removed some of the other pieces where the old concrete is cracked. That's not likely to last.

 

[killster1]

Better than before...yes, but me, I would have removed some of the other pieces where the old concrete is cracked. That's not likely to last.

well did you see how long it lasted how it was and that was a actual walkway. i feel like he will redo it in 10 years ;P

 

[BoomerD]

well did you see how long it lasted how it was and that was a actual walkway. i feel like he will redo it in 10 years ;P

The walkway looks fine...but the part at the door is still cracked. Will it last 10 years? Probably, depending on his weather. If it freezes often...perhaps not.

 

[killster1]

The walkway looks fine...but the part at the door is still cracked. Will it last 10 years? Probably, depending on his weather. If it freezes often...perhaps not.

yea i guess the question is what it will look like after 10 years (i didnt say it would last 10 years only that he would replace it in 10 years at least) maybe they can give us a yearly update

 

[Homerboy]

I will check in and update yearly. Reminder set

And yes, I've rolled my ankle on it 100 times. If it lasts 2 years and I have to re-do it, that's fine. Honestly, it took longer to draw the cat face than it did to clean and pour. 30 mins every few years and I'm content with that.

 

[killster1]

I will check in and update yearly. Reminder set

And yes, I've rolled my ankle on it 100 times. If it lasts 2 years and I have to re-do it, that's fine. Honestly, it took longer to draw the cat face than it did to clean and pour. 30 mins every few years and I'm content with that.

thanks for the reply and laughs so true

 

[Sukhoi]

Yeah I did float it a little. There's so much aggregate that it was pretty hard to get "smooth", But in reality I don't care all that much about appearances. The surrounding concrete looks like crap too I've tried sealants on hairline cracks in my driveway and they never seem to last. even the slightest movement of the slab causes them to crack/tear themselves. I keep trying though!

What sealants have you used? I put down some Sikaflex Concrete Fix https://www.homedepot.com/p/Sikaflex-10-1-fl-oz-Concrete-Fix-Sealant-7116100/300934560 a couple years ago and it's been working great even on slabs I know have been moving based on some other crack sealant (the stuff you pour out of the quart bottle from Quikrete) failing. You need to make sure you prep the crack well by chiseling out any loose stuff, make sure it's at least 1/4" wide/deep, wire brush it, and then blast it out with compressed air. Poor substrate preparation will cause most any sealant to fail.

 

[Meghan54]

What sealants have you used? I put down some Sikaflex Concrete Fix https://www.homedepot.com/p/Sikaflex-10-1-fl-oz-Concrete-Fix-Sealant-7116100/300934560 a couple years ago and it's been working great even on slabs I know have been moving based on some other crack sealant (the stuff you pour out of the quart bottle from Quikrete) failing. You need to make sure you prep the crack well by chiseling out any loose stuff, make sure it's at least 1/4" wide/deep, wire brush it, and then blast it out with compressed air. Poor substrate preparation will cause most any sealant to fail.

Like lots of things in life…proper preparation is the key.

 

[Homerboy]

Like lots of things in life…proper preparation is the key.

Stay out of my bedroom!