In 2012, Paul King, owner of King Restoration in Toronto, Quebec, Canada, was up against a project that involved demolishing and rebuilding 18 stories of concrete balconies; there was one thing missing—a good machine that could handle a project of that magnitude and improve safety for his men.
HIGH-RISE SAFETY
King Restoration specializes in concrete restoration and brick demolition on high-rise buildings where the higher heights make the work particularly dangerous. For that reason, safety is a top priority for the business.
The crews use handheld jackhammers for demolition projects of all sizes that each come with a variety of challenges. In 2012, those challenges were even greater when King Restoration came up against a job that involved 158, 16-foot-long and 5-foot-deep concrete balconies over 18 floors of an apartment building in Toronto. The concrete was spalling and debonding from steel reinforcement joists that had rusted, which increased the risk of structural failure. This required a complete demolition and replacement of every balcony on the building.
It was a massive task that, like every high-rise job, came with the risk of injuries from falls and inadvertent damage to buildings. It also would have required a lot of manpower behind numerous handheld jackhammers, which meant a higher risk of injuries that could have included hand-arm vibration syndrome, carpal tunnel syndrome, and even nerve damage. The project wasn’t just challenging on a safety scale. Since tenants would remain in the building during demolition it also had to be wrapped up as quickly as possible to minimize disruption.
King was familiar with Brokk demolition machines and their capabilities and knew that this project was perfect for putting one to work. With a Brokk machine, King and his team were confident they could tackle the lofty project safely and in just 6 months. The short timespan won King Restoration the bid over competitors that had projected 2 years using traditional handheld methods.
King worked with the engineers on the project to determine which Brokk machine could effectively demolish the balconies from a mast climber while exerting minimal dynamic force, which if great enough could affect the stability of the platform. The engineers approved the Brokk 50 demolition machine. Once the bid was locked in, King made the purchase.
DETAILED PREP WORK
The project began in June 2012 like every high-rise job—with careful preparation. With no room for errors, the crews secured plywood between the building and platforms to capture falling debris. To protect bystanders if debris did fall past the plywood, they also placed barricades around the apartment. Each worker was equipped with personal protective equipment, including harnesses, safety glasses, and hard hats.
There were 11 men and two crews on the project, a demolition crew and a forming crew. The demolition crew included five men on a mast climber along with the Brokk machine—one operated the machine and the others moved debris and prepared the steel joists. The forming crew was made up of four men who were on a separate mast climber ready to make the forms and pour concrete. There also was ground support below, which included two men that operated the hydraulic hoist to bring demolished concrete down and fresh concrete up.
18_2
The Brokk 50 machine has a three-piece boom system that allows it to work at awkward angles. This eliminates the risk of injuries to operators associated with using handheld jackhammers.
THE PROJECT
The demolition crew began at the top of the building so balconies below that were still intact could catch debris that might fall, reducing the risk of inadvertent damage to the building and injuries to bystanders. Using the Brokk 50 unit’s mounted Atlas Copco SB52 breaker, the crew carefully and precisely removed the concrete balconies.
Because the Brokk machine has a unique three-piece boom system it can reach up, over, and below objects to break up concrete. This allowed the crew to optimize their demolition process, which would have been more challenging with handheld jackhammers. Instead of raising the platform to be just under the balconies so crews could hold jackhammers at a comfortable level, they were able to position the platform a few feet below the balconies. This allowed them to place a wheelbarrow underneath the work to catch debris as it fell, which increased efficiency. If the crew were to use handheld jackhammers in this type of setup, they would have had to hold them at awkward angles, above the resting level of their arms, which would have increased the risk of injury and their rate of fatigue.
The demolition crew moved from one balcony to the next with the mast climber, demolishing an average of 10 balconies per day. As the wheelbarrow filled up, the other worker on the platform emptied it into the hoist bucket and lowered it to the ground for disposal. Each balcony created enough material to fill up to 12 wheelbarrows, which kept the hoist in heavy use.
As the demolition crew finished breaking up the balconies, the forming crew was armed and ready on another mast climber. They inspected the steel reinforcement joists and repaired those that were damaged or corroded. To prepare all of the joists for concrete, the crew sandblasted them, applied epoxy, and installed mesh for additional strength. Once the steel beams were ready, they placed the forms. The crew below used the hydraulic hoist to lift fresh concrete up to the platform, which required up to 12 trips and nearly 400 gallons of concrete for each balcony—a total of more than 2,000 trips and 66,000 gallons of concrete for the entire project.
While prepping the steel joists and bringing old concrete down and bringing new concrete up might have been tedious, because of the Brokk machine the rest of the work wasn’t. It allowed them to optimize their demolition process so they could work more efficiently to complete the job faster and on time. ■
For More Information:
Brokk has been the leading manufacturer of remote controlled demolition machines for more than 35 years. For more information, call 800.621.7856, or visit www.brokk.com.
_________________________________________________________________________
Modern Contractor Solutions, March 2014
Did you enjoy this article?
Subscribe to the FREE Digital Edition of Modern Contractor Solutions magazine.
BUTTON_ClickHere