• In this video, This Old House landscape contractor Roger Cook shows how to lift a sinking concrete slab.

    1. Cut through slab with gas-powered saw fitted with 12-inch diamond blade; that'll allow the sunken slab to lift up.
    2. Use diamond-tipped core drill to bore several large-diameter holes through slab.
    3. Use a pneumatic rock hammer to drill a 12-inch-deep hole through each core hole.
    4. In a mobile mixer, blend a grout mixture of sand, silt and Portland cement; mix the grout with water in auger.
    5. Use a hydraulic concrete pump to pump the grout through the core-drill holes.
    6. Continue to pump grout into the holes a little at a time until slab starts to rise up.
    7. Once the slab is level, cement the concrete-core plugs back into holes.
    8. Push the plugs flush with the slab, then use sponge to clean the area around the plugs.
    • Difficulty: Hard
      this is a job for an experienced, professional concrete contractor
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      • core drill
        Core drill, used to bore large-diameter holes through sunken slab
      • air compressor
        Air compressor and pneumatic rock hammer, used to drill holes through sunken slab
      • concrete pump
        Hydraulic concrete pump with pressure gauge, used to force grout under slab

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      Concrete grout made of sand, silt and Portland cement; used to raise sunken slab