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How to replace driveway concrete cut by plumber?

Hi all, we've just got our sewer reworked due to a root invasion. The plumber has cut a piece of concrete on our driveway and now we need to refill it. The area is 1060mm x 1550mm and the thickness is around 100mm. The pipe is a little above the ground and we were told that we need to install the new inspection cover in photo 2.

We've got a quote from a concreter but it's way too high for us. Is it possible to do this on our own? What do we need to get for the job? Thanks in advance.

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JacobZ

Hi @yhon031,

While it is generally speaking possible to do this yourself, any complex concreting is generally best left to the professionals. Your situation is complicated by the PVC pipe coming through the slab and the steel sewer cover.

In saying this, the principles of concreting the area are exactly the same as shown in How To Pour A Small Concrete Slab, where you would start by creating a stable compacted base using drainage gravel or road base, then set some reinforcing mesh in place on bar chairs, then mix, pour and finish your concrete.

The two main things that make it slightly more complex are the pipe coming through the slab, which would require lagging, and the steel plate which will have its own installation requirements.

The PVC pipe would need to be wrapped in abelflex, which is a compressible foam that allows for slight expansion of the concrete. This will prevent this expansion from cracking the PVC pipe.

With the sewer inspection plate, you would likely need to speak with its manufacturer for assistance to ensure that your concrete is installed in the correct manner to prevent issues. I can't say I've ever done this myself, nor can I find any readily available information, but I suspect the plate would need to be tied into and supported by the reinforcing to ensure it stays where it is supposed to during the pour and is capable of supporting the weight of vehicles after the concrete has set.

Unfortunately, the cost to install the concrete is likely high because of the sewer plate, and without knowing the specifications of how it needs to be installed, the price may be justified.

Allow me to tag our knowledgeable members @Nailbag, @JDE and @R4addZ to see if they have any thoughts.

Jacob

yhon031

Thanks a lot for the insight @JacobZ , that does look like something too complex and risky for an ameteur like me. I think we'll just start saving money to pay for the concreter😥

JacobZ

Hi @yhon031,

Unfortunately, concrete is just one of those things where there is a whole lot of potential for things to go wrong, and it is not easy to rectify those things if they do go wrong.

That sounds like a wise decision.

Let me know if you have any further questions.

Jacob

R4addZ

Hi @yhon031

Look at this as 2 different jobs, the first is lowering the pipe to below the level of the concrete. If the contractor didn't glue the top of the pipe back on then it is quite straight forward to pull the top fitting off and cut the pipe down then put the fitting back on. Note it must be low enough to allow the cover plate to go above it and for the cover plate to sit above it and still be flush with the surface of the surrounding concrete. Then lower the surrounding soil to the thickness you intend to pour the concrete and tamp it down as firmly as possible. Now for job 2 I wouldn't concrete right up to the pipe but as the pipe seems reasonably small, I would simply buy an inline connector for a larger pipe that will fit over everything and put that round the pipe but as close as possible on the side that is near the edge (so that when you concrete it in you have as thick a piece of concrete down that edge to reduce the chances of it cracking. Get the top of this as close as you can to where the underside of the metal plate will end up.

You can then put the concrete in (not between the pipe and the sleeve you have just put round it) and once you have got everything level, set the metal cover plate into the wet concrete and leave to dry (If you put it right up to the current cut edge it will also reduce the chance of cracks).

Now this is just to give you an idea of how it can be done as things can be more complicated if you want them to be, for example if you expect heavy vehicles to be crossing over this then add Rebar to reinforce it but for normal cars I personally don't think that is necessary for an area as small as this (I did something like this some years ago and there has never been an issue without the rebar). You also may want to get fancy and buy trowels that enable you to put a curved edge on the joints. There are videos that will assist if you look for them.

Nailbag

hi @yhon031

one more important point to add to the excellent advice buy @JacobZ is you need to tie the new slab to the existing. Otherwise you will get cracks very soon after the pour. This is done by drill holes into the middle of each side and inserting steel rods. These are then tied to the mesh within the new slab.

As he mentioned, this complicates the project and lifts the skillset much higher above novice.

Nailbag

yhon031

Thanks a lot guys for your valuable insights. This indeed sounds like a job too complicated for our skill level. I've talked my wife out of it with your help. I really appreciate it.

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