Denver Decorative Concrete & Custom MasonryHelp with rising driveway concrete slabs?
We’ve noticed that a slab of concrete in our driveway has risen up, and we believe it is because water has been seeping in under the slab (frost heaving?) into the soil and freezing, causing the concrete to rise up. Are there any home solutions that we can do to solve this problem?
Thanks,
new houseowner
you are probably on clay soil , take the slab up and re-lay it using coarse sand
Not much you can do after a driveway has been poured. I’m not sure if drilling a 1 hole and forcing water under the slab will help settle the slab back down (plug them back up when done). But the problem may reoccur next spring. It’s not unusual for tree roots to go long distances. But I presume you do not have any trees nearby. Here in AZ, under extreme heat, some concrete slabs expand and rise above the surface (sidewalks especially). I’m just pointing out that there are other causes besides frost heave. The only solution I know of is to tear up the concrete, lay down a thick bed of gravel (6-8 or so), then pour another 4 slab driveway. Use rebar between the joints to bind the slabs together. The air gaps in the gravel will allow space for water to freeze/thaw and reduce or eliminate that cause of the problem.
There are companies that can raise a driveway or foundation by drilling holes and forcing mud underneath to raise the section. I’m thinking that doing the opposite (pumping water and sucking up the mud) would work.
I assume when you say a slab of concrete has risen up you mean a slab of concrete and not a concrete slab (a flag) which can easily be relaid. If it’s the former, read on.
You will probably find that the chunk of concrete tilting up is thinner than it should be where the other crack is (not the crack that shows the lifting up part) I hope I’ve made that clear. The frost of course can do lots of harm but breaking up a 4inch well mixed concrete slab is hardly 1 of them. Perhaps the driveway was put down originally for foot traffic, if so it will be much thinner and the groundwork before laying the slab may not have been compacted enough. The car comes along and after a few years something gives. That’s all the gloomy side of the issue. You can remove the fractured concrete, scrape some sub-ground away and re-concrete with a good depth of a well graded mix (equall parts 20mm down gravel or limestone chippings and coarse concreting sand to 1 good measure of portland cement put through a cement mixer and mixed to a good slump. It would be advisable to lay a membrane down to retain the water enabling the concrete set more naturally. Your driveway might still breakup at other points as time goes on so you will end up with a right lucking patched up job. It all depends on your pocket and how long you intend staying and how long you can stand your wife giving you a load of gip. Hope this hasn’t frightened you too much.
Taper the drainage away from the slab. This might help pull the water away from the slab.