Hammering Away

Whether building a 100-story skyscraper or a single-story ranch, construction contractors are well aware that the stability, durability and longevity of the structures they build are dependent on a solid foundation. For that reason, they are likely to devote considerable attention to ensure that the foundation they are building on is well-prepared to support the structure.

Similarly, when deconstructing or demolishing a building, demolition contractors need to pay careful attention to effectively removing unwanted materials, as a means of preparing the site for future construction.

“From a modest family dwelling to the tallest skyscrapers, you must begin with a stable platform,” says Kevin Loomis, product manager of hydraulic attachments, based in Atlas Copco Construction Equipment’s Independence, Ohio office. “When the structure has served its purpose and needs to come down, you can be sure that some method of demolishing the footers and base materials will be applied.”

Loomis adds that for light-duty applications, frequently an excavator bucket can be used to remove a foundation. However in applications that require the removal of more robust material, he says a hydraulic hammer or breaker will reduce the material into moveable pieces.

Additionally, while using an excavator bucket may be adequate for diggiung up and removing smaller boulders, it is ineffective on larger boulders or embedded rock, says Joe Tedesco, vice president of Randolph, Mass.-based Gorilla Hammers. “Blasting poses a high risk to surrounding structures and materials, involves an exhaustive permitting process in populated areas and still leaves material that is often too large for a crusher to handle,” Tedesco says. “Using a hydraulic hammer can dramatically reduce the risk of damaging surrounding structures and does not usually require special permits. It can be used by anyone with an appropriately sized carrier and produces a crusher-ready product.”

Several equipment manufacturers and suppliers agree that the use of hydraulic hammers is necessary in most demolition applications. As a result, those contractors in the market to rent or purchase a hydraulic hammer can benefit from knowing what to consider when selecting the appropriate size and model of hammer for a given job.

APPLICATION ASSESSMENT
The number one factor to consider when purchasing or renting a hydraulic hammer is the application the attachment will be working in, according to several hammer manufacturers and suppliers. Contractors should consider the material to be broken, the tool carrier that the hammer will be attached to and whether the material exists in a horizontal or vertical structure.

Hammers are versatile in that, depending on size, they can be attached to a variety of machines including skid-steer loaders, backhoes, mini-excavators and larger excavators. Often times the material to be broken will dictate the size of hammer needed, and therefore the type of carrier needed for the tool.

“Contractors can determine what size and type hammer will be needed by determining the thickness or hardness of the materials needed to be removed,” says Roland Jarl, vice president of the EEI Group, which is based in Mahwah, N.J., and is the North American distributor for Socomec Hammers. “The harder or thicker the material is, the larger carrier and hammer that are needed.”

Al Springer, national sales manager for Carroll, Ohio-based distributor Company Wrench, offers this example. “If you have slab concrete that is 6 inches thick, that can easily be broken with a skid-steer loader, equipped with a small 500-foot-pound class hammer,” he says. “But if you have 2-foot thick concrete that needs to be broken, naturally you are going to have to move up to a larger hammer, which would require you to use a larger carrier, such as a large excavator.”

“The contractor also needs to consider whether the concrete has reinforcing steel in it,” says Greg Smith marketing manager for Allied Construction Products, Cleveland. “The thicker the concrete and the more steel reinforcement in it, the bigger the hydraulic breaker is going to have to be to break it productively.”

One rule of thumb offered by vendors, is a ratio of excavator/hammer weight used to match a hammer with an appropriate carrier. “Ideally the ratio should be in the realm of 15:1, with an upper limit of 10:1,” says Dean Barley, director of aftermarket for Terex Construction Americas, Southaven, Miss. Barley adds that the ratio is only applicable to excavators and there are other factors to consider when using a skid-steer loader including oil flow and working pressure requirements.

In some instances, however, the size of the carrier at a demolition site dictates the size of the hammer to be used. “If a contractor was performing interior demolition, where the height of the structure may be an issue, he’d want to put the attachment on a skid-steer or a mini-excavator for better mobility,” says Peter Menner, president of New Millennium Rentals, an equipment distributor based in Florida, N.Y. “Whereas if he is a pipe contractor out on the road, he would attach the hammer to a wheeled excavator or an excavator with rubber tracks. Pick the correct machine based on the application and then size the hammer accordingly,” Menner adds.

DEGREES OF DEMOLITION
In some cases, the orientation of the material to be broken will determine what type of carrier should be used and in turn, the appropriate size of the hammer. Contractors must consider whether the material to be broken is horizontal, like a concrete slab, or if it is at a 90-degree angle, such as a concrete wall.

For breaking horizontal surfaces, many vendors agree that almost any type of carrier can be. The hammer can simply be sized for the hardness or thickness of the material to be broken.

In contrast, when breaking wall surfaces it can be best to use an excavator, Springer says. “If you are breaking wall concrete, you need to use an excavator to position the hammer horizontally instead of positioning it vertically, straight up and down,” he says. “You are going to need the movement of the excavator’s boom and stick to position the hammer in a horizontal position.” 

Says Menner, “Skid-steers are good for breaking horizontal surfaces like floors because the projectiles bounce up toward the roof. However, if you’re working with walls, the projectiles tend to bounce back in your face, making an excavator at a safer distance from the debris field a better choice than a skid-steer.”

KEEP IT DOWN
An emerging trend for highway, central city and residential demolition jobs has been increasing attention to noise reduction on job sites so as not to disturb the surrounding community.

Contractors running hammers must be well-versed on noise considerations to ensure the equipment they run is not violating any local, city or county regulations.

As a result of such working restrictions, most manufacturers have released noise-suppression models that are designed to minimize the noise resulting from hammering material.

The vibration and noise generated can be reduced by using a box-style design, according to Loomis. “Box-style breakers are designed so that the percussion mechanism of the breaker fits into a four-sided enclosure and is usually isolated within the box by various types of suspension systems,” Loomis says.

Jarl says an alternative to hammering can be considered. “Rockfrac [available through Jarl’s EEI group of companieis] is a powder that, when mixed with water and poured into a pre-drilled hole, will expand and crack concrete or rock without any noise.”