My wife and I bought a house late last fall. Fast forward to today and the snow is melting. The sidewalk which runs out to the driveway, and must be used for entrance to the house, is either sunken or it was put in too low, as the sidewalk is flooding with runoff from the sides and the driveway. Can I just lay concrete or blacktop over top of the sidewalk that's there, or will this need dug up, the bed raised and redone? We will be getting concrete work done later this spring as we will be building an new garage, so would like to this at the same time. Thanks for your input.

Tear it out , raise the grade and pour new sidewalks.

Pictures would help but if the concrete is in good shape you can just have it mudjacked. If it’s cracked and junk, tear it out, put in a good base and pour new otherwise the new stuff will crack where the old did.

This is exactly correct. Just pouring over it with regular concrete will end up with the same result. There is some new concrete made to go over old, but it shouldn’t be cracked doing that. It’s mainly for resurfacing or stamping. Depending on the size I’d rent a skid steer, tear it out, and use the opportunity to level it up and possibly expand what’s there.

Tear it out, raise the grade, and repour it.

When you repour the exterior concrete around your house, make sure the concrete mix has entrained air and don’t skip on the strength of the concrete mix design. The higher concrete content and the entrained air will help the concrete last in places with snow.

The base is bad. You need to rip out old concrete and the old base. Add new class 5 and compact. Compact in stages. 4" depth at a time. On the new slab make sure you do the same. Insure contractor puts in control joints using air entrained concrete. Let slab cure until fall and then seal periodically to keep salt from cars destroying the slab. Where driveway meets garage slab insure concrete blocks of foundation have cap blocks on top course. If foundation all ready there but open on top lay shingles on top block, Put rebar on top of shingles. Dig out in front of block and put rebar on chairs in front. Wire mesh to both rebars. Pour concrete over all of it. If asphalt driveway keep concrete depth low enough to have enough asphalt over the top of block. Keep seam between asphalt driveway and slap sealed to avoid freeze thaw cycle and water getting under. If asphalt driveway there is an extrusion that looks like angle iron with gussets between both legs. Edge both sides of asphalt. Keeps edges of asphalt from failing and cracking. Concrete verses asphalt? I have been in my house for 35 years and my second asphalt driveway is starting to fail.

Bad time of year in MN to be evaluating the height of a slab or a driveway.

Wait till the frost is done f^cking schit up and gp from there.

No, you cannot just add a topping to raise it. It will fail, especially in MN.

If after the frost is gone and you need to raise it, you only have two choices, Replace it, or raise it with injections under the slab.

There are two certainties where concrete is concerned here in MN.
1) it's going to crack and heave.
2) Nobody is going to steal it.

If your existing sidewalk and subgrade is relatively sound you can pour concrete over the top no problem. Once formed add a thin layer of sand over the existing concrete to create a slip-sheet between concrete layers. Mark any large ttransverse cracks and control joints on existing sidewalk and cut in some deep v groove joints at those locations on your freshly poured 6 sack concrete with 2% air entrainment for freeze/thaw protection. Use wire mesh or Fibermesh for secondary reinforcement.

Keep in mind that by raising the level of the sidewalk you might be creating a "lake" between sidewalk and driveway so before pouring consider where rain/snow runoff and embed pvc drain pipes in new concrete to allow runoff drainage.

Tain't gunna work in MN,

Why not? Heaving that bad?

I admit my 40 years in the business was all in California.

If you bust it up(crush it) you might be able to use it as back fill under the new pour or garage floor drain..but I think crushing requires large non mobile equipment.

But it may work in a low spot somewhere.

In the meantime you could just lay a bunch of pavers over top to rock hop to the door.

Home Depot, if its just a walkway your are talking about... rent a concrete saw and make nice clean cuts. a couple neighbors with a pair of hay hooks can easily pick the small slabs out. repair the base and replace the concrete, either by replacing the cutout pieces or pouring new. Labor intensive but its not a hard job.

Phil

The concrete isn't the problem. The subrade was not over excavated and put back in atleast 95%+ compaction of the maximum dry density of the moisture density standard of the sub grade material. Followed with at least 6" of a granular base course compacted to the same 95%+ of compaction of the base course max dry density.Then the concrete with a concrete mix design strength of atleast 3500 psi including air entrainment of 2-3%. Make double damn sure your down spouts drain all runoff away from the home fnd and areas around your concrete and asphalt slabs. Water can and does destroy your fnd and slabs around the home.? MB

Good answer, Magnum Bob, and excellent remediation plan, but without pictures how do we know this is a subgrade failure?

Perhaps the driveway was overlayed at some point thus creating a low spot at the sidewalk location. We don't know.

Without seeing pictures it's all supposition on what caused this problem.

This

Depending on how much your looking at spending per sqft I'd check drainage and grading first to see if that fixes the flooding.

Again all sorts of what ifs but without good pictures its all just conjecture.

Hell, if it's just a quick fix that you want. When weather clears power wire brush the current walkway and coat with a concrete glue, put in forms and pour a new walkway on top of the old. But you have to rough up the old pretty good to get good adhesion with the glue.... heck a gallon tubb of the glue and some bender board from Home Depot, along with enough mix would make for a good weekend project without costing much. Best also to allow a few inches on each side for a full depth pour if your are going to do the whole walkway.

Phil

Most of the advice here is wrong.
First confirm that your concrete actually sunk. More than likely the frost has pushed everything around.
Find a contractor that will come out and investigate your problem and offer a solution. A few minutes with a hammer drill will tell a lot.
Find a contractor who has worked in MN for many years and not a recent transplant from a warm state. Styrofoam is your friend with exterior slabs.

+ moorwood if its a new home within 3 years you can almost bet it is soil settlement , i backfill to many homes where the builder don't give a chitt about compaction , dig it out down at least a foot ,pack base with a jumping jack ,place 6+ inches of 3 crush down hit it with the JJ, Go 3/4 crush to under slab hight hit it with the JJ ,, on bothof those gravels you want 8% moisture for optimum compaction ,

do the work no soon er than 1 month after frost is gone use rebar or mesh in the slab.

Norm

+1. Capping the slidewalks will cause problems. There are bonding agents like acryl 60 designed to adhere concrete to existing slabs. But uf you live in a place where it freezes moisture will get between it and seperate it. Then it will crack and scale. Tear it out, bring it to grade, repour. Good luck.

When someone asks if I guarantee my concrete I say, yep, guarantee against fire and theft.

Kent

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I live where the clay heaves up and down rather dramatically depending on moisture content.

Decided I wasn't going to fight it on one application and instead of installing a concrete slab, I put down a few inches of decomposed granite. Watered and tamped as I went and several years later it is still good-to-go. Some bit gets heaved up? No worries, I own a garden rake and garden hoe. No more heave. Would definitely consider for larger applications. Have seen parking lots installed with decomposed granite.

Well, I sucked the water off the walk with a shop vac three times totalling about 30 gallons of water. I think we'll end up digging up the sidewalk and getting it completely redone. Just seems like the right way to redo this.

Exactly.

If you raise the slab, where are you going to direct the water?

It obviously finds it's home in the low spot of the concrete.

Raising the slab will send it where?

Is the water just going to be directed away, or is it going to just pile up on the sides of the raised slab until it causes more/other issues?

Do you have standing water on the slab, during a down pour during the summer?

We just bought the house late last fall, and haven't seen how this is going to lay in the summer. There's two cracks in the sidewalk which they had patched. I'm thinking we're just going to redo the whole thing and probably see what the concrete guy says about raising the bed up.

Good point.
If the walk traps water (coming off if the roof) between the walk and house may be you need a drain somewhere along the walk to great the water out of the area..


The crushed gravel walkway might achieve that. There are probably other ways too.