How to repair concrete driveway?

[Shane]

Hello,

We have a sloped shared driveway and one side has just cracked from a truck going up and down the driveway. On closer examination, it is clear that the soil underneath has eroded and the concrete did not have any support anymore. What could we do to repair the damage and give it more support to ensure it doesn't get worse?

Thanks.

[MitchellMc]

Hi @Shane,

Given the erosion beneath the concrete, the best course of action would be to cut out the broken and unsupported section entirely, fill beneath it and re-pour a new slab in that area. That way, you can ensure the base is properly compacted and supported before the new concrete is laid, which is essential for long-term durability, especially on a sloped driveway that sees vehicle traffic.

As for the rest of the driveway, it would be wise to have it professionally assessed. A contractor can check for any other voids or soft spots under the surface and determine whether any soil stabilisation or filling is needed to prevent further sections from failing the same way. If voids are present elsewhere, they can often be filled with flowable fill or a polyurethane injection to restore support beneath the slab without needing to remove it.

Please let me know if you have any questions.

Mitchell

[Shane]

Thanks. Do you think we could crowbar up each piece, pour some concrete to fill underneath, then place the sections back?

If so, what could we use to also fill the gaps to ensure water doesn't get in and erode underneath again?

[JacobZ]

Hi @Shane,

I suppose you could as a temporary repair, but it wouldn't be anywhere near as strong as completely replacing the concrete. There would be inherent weaknesses where the cracks are, and as concrete driveways expand and contract and are placed under loads from things like cars and trucks, it would almost certainly crack open fairly quickly. 

I guess you would just have to weigh up whether you were comfortable with this fact or not.

If you did do this, I would just fill the gaps with concrete. You could pour your concrete base, then place the concrete piece near where it is going to go, fill up the crack with concrete mix and push it over into the existing concrete so that the concrete squishes against the old concrete and the gap is filled.

Ultimately, this repair method would not be as effective as replacing the damaged section, but for a time, it should be ok. 

If you were looking for a more permanent repair, cutting out the old section and pouring completely new concrete would be a better way to go.

Let me know what you think.

Jacob

[Shane]

Thanks again for your help. 

We were keen to crowbar up to make sure the holes weren't too big underneath. We're in an area with plenty of wombats so wondered whether that might have been the cause. 

Fortunately, the gaps underneath the concrete were fairly minor, so we went for the temporary fix of filling with concrete and relaying the pieces. The old concrete is incredibly strong (you can smash away with a crowbar and not make a dent) so we're hopeful this will last a while, even if it doesn't look too flash. Kind of a crazy paving effect!

Thanks again.

[JacobZ]

Hi @Shane,

Seeing how thick the drive is and hearing how tough it is, I am sure it will be a good, solid repair.

I actually don't mind the effect either.

Nice work, I hope it holds strong for a long time to come.

Jacob