How to Depave

There are 5 basic steps involved in a depaving project…

1. Planning
2. Tool Selection
3. Breaking!
4. Removal of pavement
5. Soil Restoration

Planning

Determine how much concrete or asphalt you would like to remove. Are you sure you want to get rid of it? It took a lot of energy and effort to get that pavement there, so make sure you want to remove it.

Determine the thickness of the pavement. Is it reinforced with metal? This knowledge will inform your selection of the appropriate tools. You can check the edges or inspect any existing cracks for clues. If you are doing a large area, it may be best to try to get a “core sample” before starting to see how thick the pavement …and what is underneath.

Call 811. This is the new national ‘call before you dig’ number. This free service is the utility notification service that will alert the utility companies to come out and mark your property where the water, electric, gas, and any cable lines are buried. Allow two business days and some nice folks will tag your street and property. And you thought all those markings were the work of your local neighborhood gang! If you see a yellow line across your proposed work site, be careful!!! Gas leaks are no fun.

You may wish to alert the neighbors about your project as it may be loud and disruptive on destruction day. You will need to figure out how to keep the area safe, how to keep kids and pets away from the area during the demolition.

If the pavement is in the planting strip or in the public right-of-way, you will most probably need a permit from your City’s transportation department. This is so they can check to see if you do a good job and don’t mess anything up.

It would also be good to start thinking about what you are going to do with the broken concrete and rubble. Ideally, you would find a use for it all on your property.

Concrete vs. Asphalt

Concrete is made from sand, cement, water and is whitish grey in color. It is harder than asphalt. It is more durable and expensive than asphalt. Most sidewalks are made from concrete. It has very little adverse effect on soil health, other than the obvious compaction. Reinforced concrete is stronger because of embedded sections of steel rebar (or any other metal rods). And as you may have guessed, reinforced concrete is harder to break. If it’s reinforced, you’ll need most probably need a phone to call up a professional to break this stuff up.

Asphalt is basically made from oil sludge and is usually black but it’s darkness fades over time. It is ‘softer’ than concrete and softens on hot summer days. It is actually the most recycled product in the world. Rest assured, that the asphalt you remove can be recycled into more asphalt (which can then again be removed ;). Most roads are made from asphalt. Since it is a petroleum oil-based product, it is not healthy for the soil.

Tool Selection

There are a variety of ways to remove pavement. You can use a sledgehammer for thin, unreinforced concrete. For larger projects, you may even choose to use a skidsteer with a breaker attachement (i.e. Bobcat). Typically, for most small home projects, an electric jackhammer and/or a concrete cutting saw should do the trick.

Here’s the lowdown on the stuff you may need, from primitive tools to complex power equipment.

Safety First!

You will definitely need protection for your eyes and ears. It is also wise to wear gloves, good shoes, long work pants, and a long sleeve shirt to protect you from flying bits of pavement. You may also want a mask to protect you from the concrete dust particles if you are using a jackhammer or concrete saw. And it is a fantastic idea to stretch before you start working, and after you are finished.

Breaker Bar – This is the most useful tool that you can have. No matter what type of pavement breaker you are using, this long metal bar (the longer and stronger, means more leverage) is essential. Leverage is your friend. This tool will allow you to move broken slabs of pavement to make it easier to break the surrounding pavement.

Pickaxe/ Mattock - These are variations on basically the same tool which is a stick with a heavy, metallic pointy thing at the end of it. The Mattock has a bit wider chisel end then the pickaxe which is great for splitting apart asphalt and concrete, and for leveraging under slabs. If the paved surfaces are already cracked, take aim, and try to expand those cracks. And also, if you can access the edge of the slab, you can use the pickaxe to leverage under the slab.

Sledghammer – This is a stick with something hard and heavy at the end of it. Basically, you want the heaviest sledgehammer that you can comfortably handle without breaking your back. This primitive tool can be used for small project areas and is most appropriate for relatively thin slabs (less than 3”). Remember to let this tool do the work, and not your back or arms.

Concrete Saw – You’ll want to use this tool if you want nice clean edges along the remaining concrete. This will also be more appropriate for removing reinforced concrete. There are various kinds and sizes.

Jackhammer – I recommend getting the heaviest electric hammer that you can handle. An 85 lb hammer is a good and useful size. The jackhammer is a useful tool for breaking up small plots of concrete and asphalt. The chisel bit and point bits will be good for concrete, while a wider spade bit will be best for asphalt. The jackhammer, as you may know, is loud and very vibratory. You can do a lot of damage with one. Be smart.

Skidsteer (i.e. Bobcat) with breaker attachment – This is what you want if you are planning to break up hundreds of square feet of pavement. It will cost you a bit more, but will save your back and your time. It will make financial sense to find other folks who want to remove concrete and you can split the rental fees.

Breaking

WARNING: Breaking pavement can turn into an obsession. I remember after my first day of breaking concrete, I rode my bike to a friend’s house, and along the way, I couldn’t help but stare at the cracks in the road, thinking how I could easily get in there and remove big chunks of the pavement.

The Breaking method should be used for areas where a clean line between remaining pavement and removed concrete is not necessary.

Anyway, here’s the basic method…

In order to break pavement, the concrete or asphalt needs somewhere to move. Therefore, the best approach is to start at the edge, or if possible, a corner. This way the pavement has two directions to move. To make things easier, a wedge should be placed under the pavement to separate it from the ground. This will facilitate the breaking of the slab, because you are separating it from its support base. Check out this helpful animation. Basically, you will want to form chunks of the concrete or asphalt that are as big as you can comfortably lift and move, typically under 1 sq. ft. The size will obviously depend on the thickness of the concrete as thicker concrete means heavier pieces. Your goal should be to make these nice sized chunks. It is a skill that you will learn after some time.

Busting stuff up using the sledgehammer or pickaxe or jackhammers actually require some amount of finesse and the idea is to work smarter, not harder. In general, you want to let the tools do the work, and not your arm muscles.

When using the sledgehammer or pickaxe, this means slowly raising the tool with one hand near the head, and then letting gravity and torque take over as you lower the head to the ground, sliding your hand to the opposite end of the handle to meet your other hand. Got it? You’ll also want to adopt a wide stance, slightly bending your knees and engage your abdominal muscles to keep yourself stable.

When using the jackhammer, your job is to basically keep it from falling over and angle it when it needs to be angled. Positioning it is key. First you want to create cracks with the point bit, and then you want to “explore” the cracks using the chisel bit and make them bigger. Again, this is all easier, if the concrete or asphalt has room to move (i.e. break), so first clear any dirt around or under the slab.

 

You may also want to consider the use of a non-explosvive breaking agent. A what? This is a powedered mix that you pour into drilled holes in your slab. Over the course of a couple of days, it quietly expands, cracking the concrete. I haven’t tried the stuff myself, but you can find out more here and purchase it from here. Let me know if it works!

Cutting

Cutting is appropriate for cutting tree wells or any work done in the public right-of-way in which some of the pavement remains and a neat clean line between the two areas is desired.

A diamond-tipped blade is preferable, but this will be a lot more expensive to rent (you typically have to pay for the amount of wear to the blade). You will want the right size blade for the job, which will depend on the thickness of the slab.

Note that concrete saws work well for cutting straight lines. You should not attempt to cut curves with the saw. If you really want a curve, the best way is to cut a series of straight lines in slightly varying angles that will eventually resemble a curve.

Removal of Pavement

Concrete chunks can easily be used again for a variety of purposes. Asphalt chunks? Not so much. Since asphalt is recyclable, you can drop it off at a local asphalt recycler for a nominal fee ($5-$10 per truck load).

For concrete chunks, your best solution is to somehow use the stuff on-site. Concrete chunks can be used as stepping stones, as retaining walls to control erosion, for firepits, for foundation floors in outbuildings, to build raised be gardens or as fill for a drainage pit. The permaculture folks refer to this stuff as Urbanite. If you or your neighbors can’t use the stuff, you can post an ad on Craigslist or Freecycle, and some happy folks will take the stuff off your hands. The reuse will hopefully prevent more concrete from being produced (the cement used to make concrete takes a whole lot of energy to produce).

You will most probably be left with bits of rubble and possible some gravel that was put in as a sub-base. Again, this stuff can be used for drainage projects so you could try to get rid of it on Craigslist or by contacting folks that may be able to use this stuff.

There are some great examples of walkway and raised beds using urbanite here :

Soil Rehabilitation/ Restoration

Okay, now you have removed the pavement and all the bits of rubble. The earth is now free, but you will need to help her breathe again. Most likely, the compacted soil is a hard-pan surface that will not allow water to infiltrate. Don’t even think about roto-tilling! The best approach is to take a spading fork or if the soil is really compacted, a pickaxe, and dig up the compacted soil. You can then mix in some organic matter such as compost to activate and bring life and microorganisms back to this dirt. This way, the bugs and worms and other critters will burrow, reproduce, poop, aerate the soil, and gladly do the work for you for free. You may also want to bring in some topsoil to mix in if you want to plant stuff right away. Be sure to plant some cover crops with aggressive taproots such as alfalfa or to help you break up the subsoil. iIf you are concerned about contamination from asphalt (a petroleum product), you can plant sunflowers. Recent research has shown that sunflowers can effectively break down hydrocarbons. Sunflowers are also very lovely.

For areas where you wish to plant perennials, you can keep adding wood chips each year, which you can get delivered for free from your power company or local arborists. If not wood chips you can add manure, leaves, or other organic matter.