You may need to break up a segment of concrete to reach an underground utility in need of repair, or perhaps you’re ready to turn a paved area into a greenspace. These steps will teach you how to complete this task and to dispose of the waste afterward.
Removing the Whole Slab
Call the utility company. Always call the local utility company to make sure there are underground utilities beneath the concrete. Hire a professional if there are; digging above a utility line like gas or electric is very dangerous.
Use safety equipment. Concrete removal creates dangerous dust and sharp fragments, so protect yourself and anyone working with you using safety goggles, dust masks or respirators, steel toe or other heavy boots, thick gloves, and thick clothing that covers your arms and legs. If you’re going to be using power tools, especially a jackhammer, use ear protection.
Cover the slab with plastic sheets to contain dust and debris if practical. This will cause a possible slipping and tripping hazard, and will make it difficult to see your work, but in some situations it could be worthwhile. If you don’t use plastic sheeting, protect any nearby windows and breakable objects with plywood sheets to protect against concrete fragments.
Obtain a large pry bar. Whether you’re using a sledgehammer or jackhammer, you may need to pry apart the pieces of concrete as you break them apart. This job will be much quicker if you have one person breaking apart the concrete and one person to follow them prying the pieces apart.
Consider a sledgehammer for thin slabs. If your concrete is 4″ (10cm) thick or less, try using a sledgehammer.
Start at a corner or edge where possible, the lateral strength of concrete increases with wider cross sections. You may find that undermining, or removing soil from underneath a small area of the slab will make it break away more easily.
Use the pry bar to pull apart the chunks of concrete after you break them apart.
If after ten minutes you’ve failed to make significant cracks or you are exhausted, you may want to try a demolition hammer instead.
Use an electric demolition. An 60 pound breaker should be sufficient for most home jobs. Only rent a heavy duty pneumatic jackhammer for extremely difficult concrete.
Only use a chisel point bit to break up concrete. This concentrates force for the best results.
Let the weight of the machine do the job; it’s not necessary to add force by pushing down. Forcing the bit will cause damage to the machine and possibly wedge the bit.
If the concrete doesn’t crack immediately, stop hammering and move over a few inches. More hammering could get the drill bit stuck and you would have to waste a lot of time pulling it out again.
Break pieces 2–3 inches (5–8cm) away from each other to minimize chances of a stuck drill bit.
Use the pry bar to pull apart chunks of concrete after you crack them apart.
Deal with any mesh or reinforcing bars you encounter. You may encounter supports inside the concrete after you start cutting. Deal with them as you go to separate the chunks of concrete:
If the concrete is held together by wire mesh, you’ll need bolt cutters to snip it apart. Large welded wire fabric will require bolt cutters, but number 10 wire can be cut with side cutting pliers.
Metal reinforcing bars will take much longer to cut apart. Use a reciprocating saw or an angle grinder with a cutoff blade.
Pull apart stuck chunks with a mattock. If chunks of concrete remain locked together, making it hard to break the surrounding area, clear the surrounding rubble and use a heavy mattock to pry them apart:
Swing the pointed end into the crack between the two chunks and pry it apart.
Once the crack is wide enough, switch to the larger flat end and pry fully apart.
Pry up the opposite side of each chunk if they still won’t budge.
Removing a Small Portion
Determine where you need to break the concrete. If you are looking for a broken water or drain line, and you can locate the general area you suspect the problem to be in, you can save a lot of work and expense. Here are some things to look for:
For plumbing problems, try to determine the location and depth of the underground pipes. Look for an outdoor faucet or sewer cap.
For water problems, look for areas where water is either bubbling up through cracks in the concrete, or seeping out around the edges of the slab.
For electrical lines, you may find you have to locate the conduit outside the slab area and dig up a length of it to determine where the rest of it runs.
For other types of repairs, or for installing new utilities that require excavating a ditch through an area paved with concrete, you may have to research construction plans to determine where to begin.
Mark the location of the portion of the slab you intend to remove. You may wish to measure distances from the slab’s edge to make an even, parallel hole for less visible repairs. Use a pencil or chalk to mark off the location.
Shut off any relevant utilities. If you are digging toward a specific line or pipe, shut off the power or water before you begin. You don’t want to risk electrocution or other dangers.
Always call the utility company to find out the location of power lines and other dangerous items before beginning projects that involve digging.
Saw cut the line as deeply as possible. Rent a cutoff or demolition saw for use on concrete. Cut the line evenly to create a clean edge when your work is complete. If you are searching for a broken water pipe,you may have to enlarge the hole after the initial break is done.
Be very cautious while sawing. These saws are powerful and can cause a fatal injury. Always wear a respirator or face mask to protect against dust and follow the instructions carefully. For any application where it is possible, use a wet cut saw and keep enough flow of water to prevent air born dust and damage to the saw blade.
Chip the concrete near the cut. Use a heavy duty hammer drill or a breaking chisel attachment in a rotary hammer to chip the concrete next to the line you sawed.
Tilt the chisel so the side you will be removing cracks loose, not the side you’re keeping.
Gradually deepen the hole. Using the same tool, work the area around the cut, penetrating deeper each time until you’ve reached the bottom of the slab. This is the hardest part of the job, since the pieces you break off cannot come free until there is a space for them to drop into.
You may need to leave tightly wedged pieces of concrete until the adjacent concrete is broken and removed.
Chip inward to make the gap wider. Once a gap has been created between the concrete you’re removing and the concrete that’s staying, chip further with the same tool to widen it to at least 3 inches (8 cm), or enough to fully remove the broken pieces.
Keep your chisel point slanted toward the beginning hole while you work around, so it doesn’t try to penetrate straight down without breaking a section of concrete free. If it is allowed to go too deep, the bit will become lodged in its hole and will be difficult to remove.
If a bit is truly stuck, you may need to use a new drill bit to break the concrete around it and free it.
Break larger pieces using a sledgehammer or electric jackhammer. Once there is a wide enough gap to avoid damaging the concrete you wish to keep, you can use the methods detailed for removing a whole slab.
Use a pry bar as you go for the quickest and most effective results.
Do not use a jackhammer or similar power tool if you are near a water pipe, electrical line, or similar item.
Remove the broken chunks and bits of concrete from the hole as it becomes larger, so subsequent pieces have plenty of room to drop in without becoming wedged. This will also make it easier to spot pipes and electrical wires.
Use bolt cutters to snip reinforcing mesh and an angle grinder to cut through rebar.
Clean up the walls of the hole. Once all the concrete is removed, chip the vertical walls of the hole to make them smooth and even. This will ensure a stronger repair (or a more attractive edge if you don’t plan on replacing the concrete).
Search for the damaged pipe (if applicable). If you’re trying to find a damage utility such as a water pipe, look for signs as you go to help you locate the pipe (such as water puddles or stains). Once you find the pipe, you may need to continue breaking concrete along its length to find the damaged section.
Avoid hitting cast iron or PVC pipes with the breaking hammer, as these are brittle and can easily sustain further damage.
Disposing of Broken Concrete
Use the rubble as fill. If you have a large hole in your yard, such as following a repair, use some of the rubble to fill it back again. Cover any pipes or other objects with soil first to avoid damaging them.
Use a heavy duty wheelbarrow. Move the rubble to a larger disposal container using only a very heavy duty wheelbarrow. Concrete is very heavy and will break light wheelbarrows.
Do not overload the wheelbarrow. Taking more trips with smaller loads is much more sustainable.
Consider renting a power wheelbarrow.
Rent a dumpster from a disposal company. If you want to get rid of a large amount of concrete, this is your best bet. Many disposal companies have a reduced rate for disposing of clean broken concrete that can be recycled or used for rip rap.
Ask in advance how full you can load it, or you’ll be forced to take the excess out or pay them to do so.
Drive it to the landfill. Be careful — your truck will not carry as much concrete as you think. Use a powerful pickup truck and do not fill the entire bed.
You can also use a utility trailer for your truck, but be especially cautious loading in that case. A too-heavy trailer will smash into your truck or spill when you attempt to stop.
In some locations, only landfills that accept “C&D” (Construction and Demolition) materials will accept concrete, and the fees may be pricey.
Building supply companies may take your old concrete for free if you call them in advance and agree to deliver it yourself.
Build a wall out of the broken pieces. Or reuse it to raise a flower bed, create a footpath, or even create urban grunge decoration.
Look for specialized concrete breaking tools and accessories at tool and equipment rental outlets if you will only need them for a single job, as these machines are very expensive.
For an area larger than 15-20 square feet, renting a jackhammer or contracting the job out to a qualified demolition person may be easier.
Use smaller tools for close work, near pipes and other fragile components of the structure.
Use the largest hammer drill or rotary hammer practical for your job. These are expensive tools, so if you only need them for one job, renting is more economical than purchasing them.
Avoid damaging reinforcing bars and mats if possible, so the patch will have similar strength to the adjacent concrete.
Wear heavy boots, gloves, and safety glasses while performing this work. For demolition hammers, breakers, or jack hammers, hearing protection is required.
Be careful when breaking concrete that may contain live electrical wiring or compressed gas lines. A call to your local utilities can save your life and a lot of money. Look in the yellow pages.
Rotary hammers have a lot of torque. Be sure to use any auxiliary handles that it is equipped with.
Read all manufacturer information on tools and follow safety rules. Do not use a piece of equipment until you fully understand how to operate it safely.
Wear a dust mask or respirator when dry cutting concrete and, if possible, use a wet cut system. Concrete contains silica and can harm your respiratory system. Older concrete can also contain asbestos; test before you start working if there is any doubt as to its makeup.
Broken concrete can have very sharp edges. Wear gloves.
Things You’ll Need
Dust mask or respirator
Heavy duty gloves, boots, and clothing
Earplugs or ear muffs (if working with power tools)
Polyethylene sheets (optional)
Sledgehammer, electric jackhammer, or pneumatic jackhammer
Large pry bar
Bolt cutters (if there is wire mesh)
Reciprocating saw or angle grinder (if there are reinforcing bars)
Additionally, to remove one section:
Cutoff saw or demolition saw
Rotary hammer, hammer drill
How to Build a Concrete Driveway
How to Order Ready Mix Concrete
How to Repair a Concrete Floor
How to Safely Dismantle a Concrete Garage
Sources and Citations
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