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WoodworkerEric
Concrete walkway sinking. Re-level or Re-do
WoodworkerEric

We puchased our first home in July 2014 and are starting to do some improvements. We have a solid poured concrete walkway that has sunk below the intended grade over the years. I have fixed the water issues but now I am stumped on fixing the walkway. With this being a solid poured walkway I can't just lift the sunken portions of it and relevel. Since the walkway has sunk about three inches it has become a place where rainwater pools and has also killed the grass in the front yard because of the constant saturt****. I know there are practices out there for Mudchacking and Polyjacking but I do not know it it would be a cost effective solution to the problem since we are also wanting to change the design of the walkway. I am wondering if you could provide some insight on what could be a solution for this. would I be better served to take out the existing concrete and repour the entire walkway and have it designed to our liking or fix the sinking concrete and add to it with now concrete to achieve our design?

A. Spruce
Re: Concrete walkway sinking. Re-level or Re-do
A. Spruce

Why did the walkway sink? Some movement is to be expected with seasonal temperature and moisture changes, 3" of movement is a tad excessive. You will need to deal with this problem before a remedy will actually be a remedy.

If sinking issue has been rectified, then you can either cap what you have or tear it out and pour new, it is my recommendation to tear it out and start over. Be sure to design the new walkway to be able to withstand your climate/environmental requirements.

WoodworkerEric
Re: Concrete walkway sinking. Re-level or Re-do
WoodworkerEric

Since the sinking has been ongoing prior to us buying the home, my best guess for the cause is miss management of water from dounspouts running into and under the walkway. I have fixed the water issue by redirecting the runoff down the driveway and away from the sidewalk/grass. It has not moved any nore since we have been there. My main question about this is there any cost savings from re-leveling it with mud or poly jacking vs. pouring a new slab. I have never taken on a job like this. If the walkway was not a solid pour it would be easily fixed but 3ft x ~35ft of solid concrete is just a bit heavy to move in place. I am also leaning more towards re-doing the entire thing. Just looking for insight on cost.

A. Spruce
Re: Concrete walkway sinking. Re-level or Re-do
A. Spruce

Patching, or in this case, leveling or adding another layer of concrete, doesn't look as good as a fresh pour, and will likely cost as much as total replacement. If you tear out the existing and replace it, then you can also add in drainage under and around it so that you won't have future settling problems.

Taking out the existing walkway will require the use of a jackhammer and a dumpster to haul away the debris. You'll likely want to hire some muscle to help move the debris as well. Of course, this assumes that you will be doing the work yourself, otherwise hiring the job out will be the easiest way to go and you won't have to lift a finger.

WoodworkerEric
Re: Concrete walkway sinking. Re-level or Re-do
WoodworkerEric

Have you heard of the ballpark cost of mud or poly jacking?

I agree that it may not look the same if we were to just add to the existing even if we were able to fix it.

I try not to higher anything done unless the job is either too big or out of my experience range. I generally can handle most projects like this without paying a crew to complete it. Though I admit this job will need extra muscle or take it in stages.

A. Spruce
Re: Concrete walkway sinking. Re-level or Re-do
A. Spruce

This is actually a good learning project, not too big, not critical to be perfect.

1 - Demo and remove old walkway. You can saw cut the bad section out if you have a portion that is saveable.
2 - Grade the area to slope away from house.
3 - Good idea, but not a necessity, adding compacted gravel base.
4 - Setting forms, one about 6" from the wall, one along the outside edge. The one at the wall will be removed as soon as the concrete is screeded. In lieu of this and assuming you are pouring against a cement footing of the house, you could attach an expansion joint felt to the footing and leave it in place. If you are pouring against wood, you will either need to install flashing between the walkway and house wall, or install a form board that can be removed after the concrete sets, leaving a gap of at least an inch between cement and wood. You also want 1/4" per foot fall away from the house for good drainage.

Note: Be careful not to over-screed and remove too much material, as this will result in hollow areas that will collect water.

5 - I prefer "jointless" expansion joints, these can be done two ways, break the pour up into sections and pour every other section. Say you have 5 sections, you'd pour sections 1,3, and 5, when the concrete is set and has a good cure, go back and pour sections 2 and 4. The other way would be to do the entire pour and use a jointing tool to create places for stress fracturing OR install physical expansion joints (2x redwood, felt joint material, etc. ).
6 - Add a brush finish to the top of the walkway to make a non-slip surface. This is done after all the trowel work is done to smooth the surface.

If you are unfamiliar with working with concrete, YouTube has vids on the subject to give you some tips and techniques.

Fencepost
Re: Concrete walkway sinking. Re-level or Re-do
Fencepost

In my opinion, you are better off removing and replacing, even if it costs more than jacking it up or overlaying it. The cost of demolition will be a minimal portion of the total cost, especially if you are of sound body and can provide the labor yourself.

As it is, the cost of overlaying or jacking will be about the same as or more expensive than the cost of a new walkway, and by removing the existing material it will allow you to assess the integrity of the subgrade and repair that if necessary to prevent a future failure. (Mudjacking requires specialized equipment and trained operators.)

Mudjacking is generally only feasible where replacement of the concrete would be difficult, expensive, or inconvenient, such as if you had a building with slab-on-grade construction that was settling unevenly, or the slab of a roadway which can't be out of service more than a few hours.

P.S. -- we can't give estimates on cost here, because costs vary by location, your exact situation, and how busy your local contractors are.

Jack
Re: Concrete walkway sinking. Re-level or Re-do
Jack

Not a concrete expert, but I wonder, as you need to raise the walk over 3 inches if it would be possible to use the old walk as base and pour 3 or 4 inches on top of it?

Jack

dj1
Re: Concrete walkway sinking. Re-level or Re-do
dj1

Jack, the sinking occurred because of excess weight and poor base and possible water erosion. Adding more weight without fixing the base, will probably bring similar results.

The best approach is to remove the sinking slab and re do it properly. Old concrete, broken to small pieces can be added to the new and improved base.

WoodworkerEric
Re: Concrete walkway sinking. Re-level or Re-do
WoodworkerEric

Well I would like to thank everyones input on this. I have spent some time now thinking this whole thing over. I think i would be better served to just remove the walkway and start over, like some of you stated. It would be much easier to start from a clean slate and make sure the base is good so this should not have to be done again. I took some time laying out a rough string line for the raplacement last night. When I figured out the overall pitch of the original construction I ralized that it had indeed sunk 3" at the worst point. Now comes more planning then the hard work of taking it out.

A. Spruce
Re: Concrete walkway sinking. Re-level or Re-do
A. Spruce

Glad we could help, let us know how your project goes.

BTW, if you're going to take it out, this will give you the freedom to enlarge and/or change the shape of the walkway, so think through the overall look you'd like to have when you're finished with the project.

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