There comes a point where repairing or repositioning concrete slabs and walkways is not worth the effort or cost and time. In this case you have the choice of replacing the material with the same thing or changing your design for a new material.
Smaller jobs like 4×4 slabs found outside many front or side doors or even a portion of a walkway that connects your home to the street are relatively easy jobs that can be performed by one or more people over a weekend.
Depending on the age and skill used to perform the original install you will be faced with a number of choices in tools you will need to remove the material.
Protecting The Area
This is a very important step that we often forget. When working around a front porch you have a great risk of damaging windows or siding with flying chips of concrete. These pieces can fly a few yards while working and once the damage is done it is a little late to explain the cost of a new glass door or window.
If you have some old plywood lean it against the house to protect the windows.
Also move your vehicles even if you are just cutting the concrete with a saw. Concrete dust will cause scratches in your paint no matter how well you wash it. If you do get dust on the car do not use a towel or sponge. Let the dust flow off the car when you apply water with your hose in a light motion.
Concrete steps are often more difficult then walkways and slabs because they should contain rebar.
Rebar comes in two basic types that are found in exterior concrete systems. The first is most recognizable and is a bar form. Bar rebar comes in many different sizes based on the size of the concrete structure but you are most likely to run into 1/2 inch rebar.
Half inch rebar bars are placed in footings. If you are working on removing a whole patio you may find a 1 foot deep footing around the perimeter that has rebar bars.
In the center of the concrete slab you are likely to find Rebar Mesh which is a steel wire screen type material welded together with 4 inch square or larger openings using a 1/4 inch metal bar wire. This material is used to stop the concrete from expanding and contracting during different cooling and heating seasons and to improve the structure of the concrete slab.
Cutting Vs Breaking the Slab
When you have an area of concrete that is adjacent to good material you want to use a concrete saw to make a clean cut between the two areas. Never believe that you can simply chisel a clean cut on concrete because it will crack.
Once you have separated the good from the bad you can go about removing the concrete in the center of the bad area by breaking it up.
If you have a small area you may be able to do this with a very heavy sledge hammer. The larger and longer the handle the better.
Your first impact should be in the center of any large part of slab you want to break up.
If you find the slab is too thick to break by hand you can rent an electric Jack Hammer at most supply centers for half a day and break the slab into piece you can manage.
Bolt cutters will aid you in cutting up rebar wire mesh but cutting larger rebar bars will require a concrete saw with a metal cutting blade or a 4 inch grinder can be used for a small amount of work.
Renting Tools vs Buying
If you are working on a project that will require many days of work you may want to consider buying some of the hand tools and smaller power tools used for the project.
It is always useful to have a good sledge hammer so this is a good investment but you may find that buying a used concrete cutter or even a jack hammer for half or third the cost may save you in the overall rental. Remember if you bought it used you can always sell it to the next guy that needs it.