I found this excellent video by Mr. Hardware on Youtube, where he repairs cracks in a slab that has been mud jacked. Mud jacking is a process where holes are drilled in a slab and a mud slurry is injected to float the slab to raise it up if it has been sinking. The bad thing about any foundation repair is that the top concrete is going to crack with any movement. So Mr. Harware came up with an excellent DIY method to fix these cracks and make your sidewalk or driveway safer to walk on. Mr. Handyman starts by filling all the cracks with a minimally expanding foam, called Touch-N-Foam Home Seal and runs it along all the gaps. Then, he shaves the foam down flat after it completely dries. At the end of this process, he puts caulk over the shaved down foam and the repair will last around five years or so. The greatest thing about using the spray foam in the cracks is that it expands and contracts with weather conditions, so it stays intact.

Materials:

• Touch-N-Foam Home Seal (spray foam, minimal expanding)
• Self-leveling caulk sealant
• A razor knife

Directions:

First, you will spray the expandible foam into all your cracks. You can get about 16 feet out of each can of foam. Then when the foam is completely dry and has fully expanded, you will cut away the excess with a razor knife.

Then, you will cover all the foam filler with caulk sealant and the job will last about five years.

This is a wonderful method of fixing cracks, I will be trying it soon.

Repair Cement Cracks On Sidewalks And Driveways