Can I pour new concrete over existing concrete?

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I have a sloping (3") concrete patio slab that is cracked. I want to pour concrete over it and level it off. Can this be done or do I have to treat the existing slab with something before hand? The new surface would be approx. 2'' thick at one end to 5'' thick at the other. Thank for any help.

  7 answers
  • Jenny Tease Jenny Tease on Aug 28, 2017
    Yes you can I just did it to raise an area but you need to some bond crete to make a thin layer so the new concrete can stick to the old concrete

  • Sharon Sharon on Aug 28, 2017
    You also have to make sure the old slab is not sealed. Pour some water from a cup on it, if it beads up, its sealed. If the water absorbs and spreads out ... your good to go, just clean throughly first.

    • See 1 previous
    • Sharon Sharon on Aug 28, 2017
      Your also going to have to make a form from wood around the slab, and oil it,,,, screw the boards together so they don't come apart. I would check with the store, but I think you would want Quikcrete self-leveling. You might want to ask the guy if it needs some wire screen in it too to keep it from cracking. If the old slab is sealed your going to have to wash it with a power washer and use muriac acid on it, and for this you need rubber boots, glasses, rubber gloves, and a plastic watering can.
      There are a lot of videos on YouTube.

  • Johnavallance82 Johnavallance82 on Aug 28, 2017
    A PVA Solution to help it adhere.

    • Larry Larry on Aug 28, 2017
      Thank you for your help Johnavallance82. Don't know what PVA Solution is , but I'm going to Google it to find out.

  • Kim Kim on Aug 28, 2017
    Why is it cracked? Find out why it is cracked and address that issue before pouring more concrete on the same spot.
    : )

  • Bj Blyth Bj Blyth on Aug 28, 2017
    please visit the Quikrete website. They have ways of making concrete look brand new and beautiful!

  • Rae Rae on Aug 28, 2017
    My thought is if the old is cracked the new may crack as well. Check your drainage. We had that problem and had to put down new after putting in drainage tile. If you live in a cold/freeze area your new may crack again because of the shifting. It also depends on the size of the piece. The bigger the more chance of a crack. I finally gave up and removed all the concrete and replaced it with pavers that can shift without the danger of cracking.

  • Deanna Nassar Deanna Nassar on Aug 29, 2017
    Simply paving over will still leave the problem there . It will crack again. You may need to remove a section and fill in that area so it looks like a sidewalk. They use expansion joints; a material that can give when heat makes the concrete swell slightly. At the very least you have to open the crack so you can get cement down to the ground level.