The versatility of compact equipment came into play during a recent demolition project at the University of Michigan in Ann Arbor. Working at a medical science building — part of the university's massive health center complex, Ohio Concrete Sawing & Drilling Inc. removed a portion of an animal laboratory that was being renovated, according to Skip Aston, president of the Sylvania, Ohio-based concrete sawing and drilling company.
Aston says the project involved the removal of 1.2 million pounds of concrete from an operating hospital without disturbing normal hospital activities. Demolition work required removing 4,500 square feet of 5-inch concrete ceiling and 7,600 square feet of 6-inch to 10-inch concrete floor. Even though the concrete floor being removed was on grade, removing it required using a freight elevator to move the material to the closest loading dock.
"The compact equipment we used allowed us to remove the 1.2 million pounds of concrete much quicker than would have ever been possible with laborers and hand tools," says Aston. "It was also far safer than attempting to remove this material by hand."
To minimize the impact on hospital activity, Ohio Concrete made a decision to use electric concrete saws, fork trucks and excavator. The use of electric equipment eliminated any fumes normally associated with gasoline or diesel powered concrete saws, and minimized the noise.
In addition, all construction activity had to occur between 7:30 a.m. and 5 p.m. Sawing activity was restricted to six hours a day between 9 a.m. and 3 p.m.
Over the past few years, Ohio Concrete Sawing & Drilling has purchased several electric-powered fork trucks and excavators in an effort to remove concrete from the inside of buildings in the safest and most efficient manner. Ohio Concrete's operators used their small electric fork truck to support the ceiling while sawing the pieces free. The ceiling was cut into 3-foot by 7-foot pieces weighing about 1,000 pounds, while each piece was supported with electric fork trucks.
Ohio Concrete attached a wall saw to scaffolding allowing their operators to cut the ceiling upside down from below. The scaffold was locked into place using jack screws to ensure the wall saw was secure during the sawing operation. Attaching the wall saw to the scaffold allowed operators to saw the 4,500 square feet of ceiling from below without exhausting the operators. Sawing the ceiling while it was supported in this manner was the fastest and safest way of removing the ceiling.
According to Aston, it would have been impossible to do any of the work from above the ceiling because the area was very congested with steam lines, water and sewer lines, electric conduit, and piping for oxygen. Attempting to break the concrete from below would have been very dangerous to construction personnel and would have damaged some of the utilities resting on the concrete being removed. Also, breaking the concrete would have created far more noise and dust than the sawing did.
Prior to removing any of the floor, Ohio Concrete personnel finished the sawing and removal of the ceiling. This gave them a solid surface for operators to operate the fork trucks and walk on. The floor was cut using a 40-horsepower electric concrete saw. The entire area was cut into 4-foot by 4-foot squares. Removal of the floor was done using electric fork lifts and a mini electric excavator.
Normally crews would have used their fork trucks to remove this concrete, but they discovered that the mini excavator was faster because it did not require the use of any anchors normally used when removing concrete with a fork truck. The excavator also had more leverage when lifting pieces that contained abandoned plumbing lines, electric conduit and reinforcing at the bottom of the floor slab.
Aston says the project was very successful not only because it was completed on time, it was also done with minimal disruption to hospital activities. The tools used created no fumes, no vibration and very little noise. Employees working one floor away were unaware that crews were removing over 1 million pounds of concrete from the floor below.
Ohio Concrete has been in business for 25 years. Aston, who started the company in 1981, is chairman of Concrete Sawing & Drilling Association's safety committee. During the construction season, Ohio Concrete completes nearly 2,000 projects each month in Ohio and surrounding states. Ohio Concrete focuses their efforts on service work. Many of their trucks are equipped with generators powered through a PTO. These generators allow them to use 40-horsepower electric saws very easily without having to connect to 480-volt power in the building where they are working.