A Lesson in Teamwork and Technology July 2009
Tilt-up and Telebelt® technologies combine to achieve high marks for fast, efficient construction of three schools in southeast Florida
STURTEVANT, WI (May 26, 2009) – “AAA”, the code name for Duval County’s new $76.5 million high school in Jacksonville, Florida, is synonymous with the high marks being achieved by the tilt-up construction technique and Putzmeister Telebelt® building the facility in high gear.
With occupancy slated for August 2010, the public school needed an aggressive construction timeline. They turned to the tilt-up method, one of the fastest growing industries in the U.S., to compress the schedule. With tilt-up, wall panel construction can proceed while the rest of the building is still being designed; the method offers quick erection techniques; and other trades can work sooner because the floor slab is poured first.
To advance this momentum, the tilt-up process has teamed up with a Telebelt truck-mounted telescopic belt conveyor, which is taking the project to the next level in speed and efficiency by placing concrete quickly, smoothly and precisely as well as backfilling materials with ease.
Building the first new high school in Duval County in 20 years, W.G. Mills, Inc., of Jacksonville, Florida, serves as the design and build lead for constructing the 2,177-student capacity facility. Jim’s Concrete of Brevard, Inc., (Jim’s) with locations in Melbourne and Jacksonville, Florida, is the concrete contractor responsible for placing 15,000 total cubic yards (11,468m³) of concrete; and ready mix supplier Cemex of Bay Meadows, Florida, is supplying various concrete mixes ranging from 3,000 to 5,000 psi.
Large Job, Low Slump The two-story 263,937-square foot (24,520m²) facility requires 471 panels, considered a large job within the tilt-up industry. The biggest panels, up to 60 feet (18.28m) tall, range in thickness from 7.25 to 9.50 inches (184 to 241mm). Although tilt-up panels are normally formed on a concrete slab that also serves as the building’s floor, this particular job site required temporary concrete casting beds around the perimeter of the building footprint. This limited close access when placing concrete.
To help overcome this obstacle, a Telebelt TB 110 model from Jim’s fleet offers a long 106-foot one-inch (32.34m) horizontal reach. In addition, the TB 110 can handle from a zero- to 12-inch (305mm) slump so it can easily place the low five-inch (125mm) slump concrete with large aggregate, a mix desirable for panels.
Harry Jacobsen, vice president of construction at Jim’s says, “With the Telebelt, we have control over the slump because if it’s a five-inch (125mm) slump going into the hopper, it’s a five-inch (125mm) slump coming out the end hose.”
“The Telebelt works great for tilt-up,” adds founder and owner Jim Jacobsen of Jim’s. “We can pour tighter because the concrete isn’t under pressure when it comes out of the end hose; therefore, it doesn’t move or disturb any inserts or various liners that we lay down first. Plus, when you stop the belt, the concrete stops instantly so you don’t end up with too much concrete in a panel.”
A Clean Machine Another assignment for the Telebelt is placing concrete for the school’s stairs, sidewalks and courtyard. During this portion of the project the contractor realized yet another advantage of placing concrete with a Telebelt—virtually no concrete splatter. On a similar project, construction of the $63.5 million “CCC” High School for Florida’s St. Johns County School District, the conveyor’s smooth concrete flow and precise placement prevented splattering nearby walls that were already painted. This avoided expensive cleanup costs and reinforces the TB 110 as a clean machine.
Plus, when required to reach under low clearances and access difficult-to-access areas during the indoor construction of the “AAA” school auditorium, the belt conveyor’s main boom could be telescoped through a window to place both dirt and concrete. This significantly reduced labor costs and improved efficiency.
“On this particular job, backfilling about 900 cubic yards (688m³) of dirt over a sloping 12,000-square foot (1,115m²) area would have normally taken about two and a half weeks to complete,” says Harry Jacobsen, “but we finished it in only three days with the Telebelt.”
More School Work On the heels of “AAA” High School and with the same completion date of August 2010 is the construction of “QQQ” High School for Florida’s School District of Clay County. Responsible for managing the construction project is M.M. Parrish Construction Company in Gainesville, Florida.
“QQQ” is also utilizing a combination tilt-up and Telebelt construction approach, again relying on Jim’s 30-year-old concrete contracting business. Ready mix supplier Cemex in Orange Park, Florida, is supplying 12,000 cubic yards (9,175m³) of concrete for the school, which includes concrete for 225 tilt-up panels, sized up to 62 feet (18.90m) tall. Although there are fewer panels than the other two school projects, the panels are much larger to accommodate the taller three-story educational facility that encompasses 290,000 square feet (26,942m²).
For this newest tilt-up school construction project in Orange Park, Florida, the belt conveyor gets extra credit for proficiently handling numerous concrete and material placing applications on the same job site – seven in total. This included backfilling stone and placing concrete for the footings, which is a dual task the unit can accomplish the same day, with the same machine setup. The unit also placed concrete for the tilt-up panels and slab-on-grade work, conveyed dirt and concrete through a window for constructing a breezeway and is scheduled to place concrete for the courtyard and sidewalks.
“Although the Telebelt is a great tool for placing dirt, stone and four-inch (100mm) rock, its versatility allows us to place concrete equally as effective,” says Harry Jacobsen.
The three schools combined required over 1,200 tilt-up panels and 40,000 total cubic yards (30,582m³) of concrete. By combining the tilt-up method with the TB 110’s capabilities, Jim’s is taking full advantage of current technological advances in construction techniques and equipment to meet the three rapid school completion deadlines with high-quality results.
Doing the Math While the Telebelt has garnered popularity since its 1997 introduction by Putzmeister America, its appeal in the southeastern U.S. has been slower in coming. However Jim’s, one of the largest commercial concrete contractors in Florida’s Duval and Brevard counties, looked outside the box. Deviating from more traditional concrete and material placement methods in the southeast, the concrete contractor purchased a Putzmeister Telebelt TB 110 model and optional three-cubic yard (2.3m³) capacity rock hopper to complement the company’s fleet of three truck-mounted concrete boom pumps.
Even though the conveyor is well-suited for material and high volume concrete placement with its maximum outputs up to six cubic yards per minute (4.60m³/min), owner Jim Jacobsen further analyzes the financial figures for handling more typical concrete placing jobs with the machine. Jacobsen, with a college degree in accounting but a passion for construction, can read between the lines of a balance sheet for better understanding other pertinent factors that affect the company’s bottom line.
“I’m glad we invested in the Telebelt because it is a big labor saver. We use the machine to easily reach inside low buildings, which avoids using slick line with a pump; and we rely on it to convey extremely difficult-to-pump concrete mixes for applications outside of tilt-up,” notes Jim Jacobsen. “Plus, it is often the only safe alternative for backfilling materials.”
Unidentified Benefits Jeff Phelps, Jim’s vice president of safety and human resources, adds other unidentified benefits to the equation. Phelps says, “With the Telebelt’s unique design, gravity takes care of the concrete flow from the end hose so there’s no need to push the end hose around when placing concrete. Therefore, our hose men are less prone to injury or fatigue.”
According to Phelps these unknown factors may not be evident on a financial statement, but they’re priceless in avoiding increased insurance premiums, workmen’s compensation and other employee health costs. He comments, “Although it’s something you just can’t calculate, it makes sense to let the machine do the hard work.”
Even though initially experiencing a learning curve, Jim’s operators now fully appreciate the belt conveyor, which Phelps calls “a different animal” due to the unit’s special operational characteristics. It required training personnel how to effectively operate the model and educating ready mix drivers about the importance of a steady flow when discharging concrete. However, the continued use of the machine in various applications, from footings to tilt-up walls as well as backfilling work, has steered company personnel towards even greater preference for the unit today.
“With the Telebelt, we can place any type of concrete mix possible and also backfill many different types of materials,” concludes Jim Jacobsen. “I’m planning to buy another one when the Florida market turns around.”