3 Alternative Concrete Demolition Methods

Hole in concrete

Concrete is one of the most common materials a demolition contractor deals with. Most structures and job sites are filled with concrete, but properly demolishing it requires more than a one size fits all solution. There are a number of ways to dismantle, destroy, and remove concrete in all shapes and sizes, and the right method depends on the specifics of the environment. Using equipment like excavators is common, but here are a few alternatives when more finesse is required.

Using expansive grouts for demolition

Most think of demolition as loud and dusty. That can be true, but there's another side to it. The use of expansive grouts is a perfect example of this quieter side of demolition. Expansive grouts harness science to gradually break apart blocks and slabs of concrete. To use this technique, holes are drilled about 8 inches apart around the concrete to be demolished. These holes should be about 1 1/2 inches in diameter and reach 80 percent of the thickness of the concrete. After cleaning out any dust and debris, grout can be added and will begin to crack the concrete within two to eight hours. It does this by expanding up to four times its volume and creating 20 thousand psi of expansive force. When vibration and noise needs to be kept to a minimum, or when working in a confined space, expansive grouts can do the job larger machinery can't.

Micro-blasting in demolition

Breaking concrete from the inside out requires less force than breaking it from the outside in. The tensile strength of concrete, which must be overcome to break concrete from within, is only about 15 percent of the compressive strength, which must be overcome to break concrete from the outside. The traditional demolition technique to take advantage of this relative weakness of concrete is dynamite to create an implosion of a structure. However, this method only accounts for about 1 percent of all demolition projects. Micro-blasting employs a similar method as dynamite, but creates a smaller, more controlled blast. Similar to expansive grout, the first step is to create deep holes in the concrete. Then, two cartridges of smokeless powder are placed in the clean holes along with a firing pin. The resulting blast is capable of breaking thick concrete slabs, but minimizes flying debris. The blast is so controlled that personnel only need to stand about 30 feet away at the time of detonation and no blasting license is required. This is an ideal solution for many projects when an expedited timeline is necessary, and cleanup needs to be kept to a minimum.

Hydrodemolition

In cases where an entire slab is not being removed, but rather resurfaced, water can actually serve as a demolition tool. Through hydrodemolition, jets of water are sprayed at concrete at 20,000 psi. This allows for clean lines to be cut in the concrete, or the surface to be removed to almost any depth. As opposed to similar cutting by machinery, hydrodemolition eliminates the risk of microcracking. This makes this method ideal when the foundation of the slab needs to remain intact. The limitation to this method is that there must be a water source nearby to supply at least 10 gallons per minute, but as much as 60 gallons per minute. Water can be brought into the site, but that of course increases costs. Proper disposal of the water is also an important factor and regulations will vary from state to state.At Demolition Technologies, we possess a depth of experience that allows us to employ the proper demolition techniques for any job. Contact us to learn more about our demolition capabilities: 918-379-0966.