Do you have a concrete slab that has started to sink little by little? Or maybe you have one that has been in need of concrete repair for a long time now?
No matter which one it is, let us have a look at concrete raising on this article. There is one article about mudjacking vs. polyjacking on this site, but it was more about the comparison between the two.
For this one, I’d like to concentrate more on the process and how it works. I guess the first question would be that does concrete raising work?
Indeed it does and it has been working for something like 100 years already. It’s not a forever solution, but the results last for several years.
That would mean that if you have a slab that is on the second half of its expected life, and if the raising is not that expensive, it could be a better option than replacing the slab yet. It can be a matter of cost in many ways actually.
Decorative concrete gets more expensive the more complex it is. If you have invested in your slab a lot, it’s more than likely that raising it will be cheaper than getting a newly decorated one that is on the same level.
Unless you can do the work yourself.
How to raise concrete
The sinking of concrete slabs is most often caused by voids under the slab. These might have been caused by water slowly removing material, ground heaving, or by pressure.
No matter what is the case, to get the slab back up you would need something to put under it. Mudjacking vs. polyjacking work in a little bit different ways.
Mudjack concrete raising
So what is mudjacking? When mudjacking is done, limestone aggregates with cement are forced under the concrete from holes that are drilled into the slab.
The mix will fill the voids and lift the slab by pressure from the machine that is used. The concrete lifting machine can be a mudjack pump that will feed the cement lifting mix through the holes that were drilled.
The concrete lifting can be done by other means as well, but I’d maybe use polyurethane for that kind of lifting method. Hydraulic pumps can lift quite heavyweights, but the problem is getting the cement mix under the slab evenly without a proper pressure tool.
That being said, you need something to pump polyurethane under the slab as well. For most people, these are not DIY projects.
So is mudjacking worth it all will depend on the expected age of the slab. If you DIY, you need to rent some machines to be able to do it.
The problem might be that proper machines won’t be even rented depending on local laws. If it’s not an option, the only way to know is to make some calls and compare prices.
Polyurethane concrete raising
When it comes to the DIY department, I think polyfoam concrete lifting might be harder to achieve. That’s because the way it works needs even more special tools than mudjacking.
Raising concrete slab will work pretty much in the same fashion. You need to drill holes for the polyurethane to be injected.
Polyurethane has two components that react with each other when they come together at the concrete hole. This will cause the expansion and lifting of the concrete.
Before injection, you need to lift the slab a little, hopefully to the correct height. After that is done, the polyurethane is injected and it will expand and fill the voids under the slab.
It will expand and set very fast so if the slab is lifted to the correct height, the extra will come off under it and set in under half a minute. You can drive a car on it on the same day so it’s a lot faster than mudjacking that needs curing time.
The advantage of this method is that the foam is very light, it won’t add more weight to the ground so it won’t cause extra sinking because of that at least.
DIY concrete raising
For the sake of keeping it simple, I’m going to assume that the ways to raise the concrete would be by cement mix or by the use of soil. Both are something that anyone of us should be able to get.
For concrete leveling DIY working, you need to be a little resourceful as the lifting of the concrete can be tricky. You can use hydraulic pumps, but getting the lifting force on both sides of the sidewalk, for example, can be hard and you might need to build a tool for it yourself.
Sidewalk
Something like a sidewalk you might be able to fix by using soil if it’s not too wide. The wider it gets the harder it will be to lift and fill under.
That being said, you need a way to lift the sunken end. If there is more than 1 edge, it gets even more complicated as you will have to lift it 1 end at a time or both ends at once.
Whichever way you choose it will be hard work. Depending on the size of the concrete, you can use either leverage or you can dig and use something like a car hydraulic jack.
At this point, you might realize that hydraulic jack might be hard to use in that kind of condition so you might want to invent some kind of helping tool that can handle the weight of the concrete, is easy to place under the slab, and is easy to lift with it.
When you get the piece of concrete lifted, you need to fill it under it with soil. It’s hard to get it there compact enough, but it can serve as a temporary solution or it might last surprisingly long before sinking with rain and such again.
Mudjack
Before even beginning, I think that correct concrete raising should be done with professional mudjack equipment. It’s hard to come by with alternatives that can get enough pressure for it to work like it’s supposed to.
I was thinking of maybe a grout pump could do it, but I’m not sure if it can get the cement mix under the slab effectively. So let’s just go with how it’s supposed to be done.
First, the holes should be drilled like mentioned before, from the sunken end towards the end where it’s not. Or if the whole slab has sunken then it would need lifting all around.
When the holes are drilled, the mudjack pump is used to pump cement mix into the hole and under the slab. It will start lifting from the sunken end.
When it’s at the correct height, you move to the next hole and fill it up as there is free space there now. Work like this until you are at the other end.
Conclusion
I hope this makes some sense in what is concrete raising and how it is done with different methods. I included the DIY concrete raising after some thinking, but I honestly think it will more than likely be a waste of money and time to do it yourself.
The equipment rent will cost, your time is valuable as well and the professionals should be able to do it well enough for it to last longer. If not done well, it could even be harder to fix in the future.
I know there are people out there who can handle it more than well, but for most, it might just be waste of time.
The main thing I’m concerned about in a job like this is that the fix won’t get under the slab well enough. As said before, there are multiple reasons for concrete to sink and it’s more than likely to do that with time.
If it’s not done properly it might just be the same situation next year or even worse. But when it comes to concrete raising, I think it’s a worthy try with expensive concrete slabs and why not cheaper ones depending on the price tag.