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Sidewalk - Repair/Replace

jtdoyle1

jtdoyle1

Well-Known Member
Apr 11, 2006
2,598
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Ankeny, IA
I had to take out a 4 ft. x 8 ft. section of public sidewalk recently due to a tree root pushing it up. I have everything graded, formed and ready to pour the concrete. I'm a little nervous about screwing it up because I probably know just enough about concrete work but I don't know what I don't know- if you know what I mean.

Any advice for a small job like this? Which type of quikrete to use? Do I need expansion joint material on either end of the new sidewalk? Any tips or tricks to be aware of?

This is Ankeny, BTW. Thanks.
 

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I dont work with concrete all that much, but the main thing would be to watch the water you add. Don't keep adding more just so it's easier to work with.
 
My advice is that mixing by hand sucks. Rent or borrow or buy one of those cheap electric mixers. I only mix by hand if it's something like 5 square feet or less.

If it's not on your driveway portion, just use whatever is cheap. The less water you use, the stronger it is.

And if you don't like the results, you can always redo it....
 
If you've made it that far, you know enough. It's not a spaceship, and it's not driveway size. Do what the bag recommends and you'll be fine.
 
If you're going with a 4" slab you're going to need a LOT of 40# bags.
 
SCNCY said:
Curious, if this is a public sidewalk, why isn't the city doing it?
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Homeowners own the sidewalk. If it cracks, you pay for it.

But check with the city first. Some have requirements for the mix used. And make sure you get the permit. Neighbors found that out the hard way.
 
I would put a felt expansion joint at each end or else it will crack. And if that is the case, you maybe wouldn't need a sawcut or troweled control joint in the middle, since the concrete will have room to expand in every direction. At least that's my theory with my limited experience. To be safe you could do a control joint (a troweled groove) half-way between each end.

Also, the existing sidewalk looks a lot like asphalt. Or maybe its just really old concrete or...or a lot of aggregate??
 
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Contraction joints (sawed or troweled joints) should be typically spaced at 24-30 times the slab thickness, and be located such that excessive aspect (length-to-width) ratios are avoided. Square panels are best. Aspect ratios of 1.5-1 or greater will tend to crack somewhere at an intermediate location.

Your 4'x8' section of sidewalk has an aspect ratio of 2:1, so an intermediate contraction joint would probably be a good idea. Contraction joints are typically cut/troweled to be a minimum of 1/4 of the slab thickness.
 
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In an effort to further confuse you: I think expansion joints in concrete are way over rated and generally offer another place for water in be introduced into your base course and aggregate (you are putting 4"-6" of 3/4" gravel down below your concrete, right?) and will cause more harm than good. Most of the specs I've seen call for expansion joints on 80' intervals for curb, gutter, and sidewalk. So, if you look at the section of sidewalk you're replacing and there's an expansion joint remotely close, I wouldn't bother with any. Just do a tooled contraction joint in the middle of your 4'x8' rectangle to get it to crack there and you'll be fine.

http://overlays.acpa.org/Concrete_Pavement/Technical/FATQ/Design/Expansion_Joints.asp

Also, remember to write your initials and date it when you're done. Good luck.
 
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Good luck with your Repair/Replace effort. If you farm it out to someone, avoid Mitch McConnell, he obviously can't get it done. :jimlad:
 
DeftOne said:
Contraction joints (sawed or troweled joints) should be typically spaced at 24-30 times the slab thickness, and be located such that excessive aspect (length-to-width) ratios are avoided. Square panels are best. Aspect ratios of 1.5-1 or greater will tend to crack somewhere at an intermediate location.

Your 4'x8' section of sidewalk has an aspect ratio of 2:1, so an intermediate contraction joint would probably be a good idea. Contraction joints are typically cut/troweled to be a minimum of 1/4 of the slab thickness.
Click to expand...

:eek:​
 
DeftOne said:
Contraction joints (sawed or troweled joints) should be typically spaced at 24-30 times the slab thickness, and be located such that excessive aspect (length-to-width) ratios are avoided. Square panels are best. Aspect ratios of 1.5-1 or greater will tend to crack somewhere at an intermediate location.

Your 4'x8' section of sidewalk has an aspect ratio of 2:1, so an intermediate contraction joint would probably be a good idea. Contraction joints are typically cut/troweled to be a minimum of 1/4 of the slab thickness.
Click to expand...

Uhhhh. o_O :D

Cut the joints so it matches the rest of the sidewalk. Follow the directions on the bag. If you got as far as getting everything formed, you've got the skills to do the rest.
 
DeftOne said:
Sorry if I confused anyone. I'm an enginerd, and sometimes it's hard to tame the beast.
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I used to spend a great deal of time planning joints to optimize function and the look only to have concrete contractors totally ignore them and tool or cut the damn ugliest joints complete with acute angles and such that made my head explode and I am not even an engineer.

We can move on to "wire mesh or no?" now. :rolleyes: For the record my own exposed aggregate walks (old style, framed in by 2x4 left in place) has #3 bar in it, mostly to tie all the 2x4 to the panels.
 
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