Whether you are renovating or repairing, you may need to remove an existing concrete slab from your house or garden. Cured concrete is incredibly strong and that's why it's the material of choice to support buildings. Breaking up a concrete slab is very physical work, even if you have access to machinery and pneumatic hammers to help you. Make sure you are in good physical shape to undertake this task.
Start at a corner of the slab. Use the pickaxe to dig out the edge of the slab until you can see the bottom of the concrete.
Get a helper to wedge the pickaxe under the corner of the slab and hold the handle down so the head is applying upward pressure to the slab.
Strike the top of the slab repeatedly with a sledge hammer about a 30 cm (1 foot) away from the corner where the pickaxe is wedged. The concrete slab will begin to break apart as you strike it with the sledge hammer and your helper continues to apply more and more upward pressure from underneath. When the piece breaks free, remove it from the slab and wedge the pickaxe under the slab again. Continue beating and breaking, moving the pickaxe as you go, until the slab is entirely removed.
Break up thicker concrete slabs using a chipping hammer or a pneumatic hammer. Either machine will provide the repetitive force needed to shatter the concrete and you will not over strain yourself trying to break apart a 25 cm (10 inch) slab with a sledge hammer. Pneumatic hammers are very large and are connected to excavation machines.
Cut through the slab bar (if your slab has a steel rebar in it) with an oxyacetylene torch to separate the concrete and slab bar into pieces that can be removed.
You can "score" the concrete in a grid pattern with a concrete saw to make it easier to break. Cut into the concrete about 7.5 mm (1/4 inch) deep before beginning to break it up, and not only will it break easier, but it will tend to break along the cut lines and make the concrete pieces more manageable. Use this method to break an interior slab where you cannot access the bottom of the slab with a pickaxe.
The edges of broken concrete can be as sharp as broken glass. Always use care when handling them and wear gloves. You can not only get a serious cut from a sharp edge, but the concrete dust can get into the cut and cause a severe infection.