Mudjack Sidewalk

Trip hazard

Before, Trip Hazard

I decided to go ahead and have my sidewalk mud-jacked.  I had a definite trip hazard where my driveway and sidewalk met.  It was about a 1.5 inch drop-off.

Additionally, I could hear the hollowness beneath my driveway right in front of the garage, and cracks were starting to form where the rebar was holding it up above the surface.  I determined that I’d prefer to push off replacing my entire driveway, and hope this might reduce the number of cracks that were forming.

I asked the worker if I could watch him while he worked, and I found the entire process quite fascinating.

  1. It’s a two person process, where one person constantly mixes the limestone aggregate and fills the pump, while the second person dispenses it at the other end.
  2. They drill 1-inch holes in the concrete approximately every 3 feet.  They use these holes to insert the pump nozzle.
  3. They pump the mud in each hole until it starts to push the nozzle out, and then move the nozzle to the next hole.  They revisit each hole several times throughout the process, because as one void is filled it raises the concrete slab slightly, creating a larger void in the areas around it.
  4. After the voids beneath the concrete are filled, they use the same pump nozzle to do the final leveling of the concrete.
  5. They had to cut the joint between my sidewalk and driveway with a wet-saw.  This cut the rebar that was now bent and kept the concrete from returning to the correct position.  It also relieved any friction between the two concrete sections that kept it from moving back into position.
  6. They stuck a cork in each hole and then filled it with a concrete grout.
After, Level surface

After, Level surface

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