Putzmeister America’s Equipment Helps Contractors Think Green
Putzmeister America’s Equipment Helps Contractors Think GreenSTURTEVANT, Wis. (November 2004) – A new $141.5 million contract for the construction of a federal building in downtown San Francisco is making project contractors think "green." Not only because of the dollars involved, but also because of the environmentally-friendly approaches being utilized in every construction aspect possible.
Although funding for the 234 ft. tall building was approved 16 years ago, construction did not start until 2002. The 19-story, poured-in-place, federal office tower is on land donated by the City of San Francisco. The new building allows federal agencies currently at leased facilities throughout the city to be located in one place.
The architects, SmithGroup Inc. of Detroit, Mich., and Morphosis Architects of Santa Monica, Cali., were predominantly chosen for their environmentally-friendly and energy-efficient designs. Consequently, this unusual project has windows that open to allow air circulation through the 65 ft. wide tower, eliminating the need for air conditioning. Vice versa in winter, the building is designed to help generate its own heat.
A great deal of the energy savings is due to the increased amount of concrete per square foot. This extra concrete results from a highly extraordinary "wave" design (virtually the shape of an ocean) underneath each deck. With more concrete to cool, a highly efficient air flow results when windows are open and warmer temperatures consummate because of reduced air flow when windows are closed.
Project management is handled by Hunt Construction Group, Inc., and the general contractor is Dick Corp./Nibbi Bros./Morganti, a joint venture. Typical to northern California, projects use many different sub-contractors to handle a break down of the larger tasks. For this particular assignment, Webcor Concrete Construction of Hayward, Cali., is being utilized for the forming and vertical aspects and Dolan Concrete of San Jose, Cali., for the flatwork. Both sub-contractors are relying upon Interstate Concrete Pumping of Hayward to place the concrete.
Although Portland cement is produced from virgin materials in an energy-intensive process that generates greenhouse gases, it is a necessary ingredient. However, replacing half of the Portland cement with slag cement mix provides substantial environmental benefits. Slag cement is a product recovered from a blast furnace during iron production that substantially lowers the embodied energy and emissions in concrete and reduces the amount of virgin material needed to produce the cement. This special slag mix is being supplied by Bode Ready-Mix of San Francisco and tested for pump-ability with Putzmeister equipment.
Because the Putzmeister products handle the concrete without difficulty, Interstate Concrete Pumping provided Putzmeister equipment to complete the job.
Joe Middleton, estimator and project manager for Dolan Concrete says, "The Putzmeister equipment supplied by Interstate met our specific reach and volume requirements. They selected Putzmeister’s 52Z-, 55- and 58-Meter truck-mounted boom pumps for placing large areas of concrete below grade up to the third floor. Then, they supplied an effective combination of placing booms, towers and trailer pumps. The company certainly understands how to effectively set up placing boom jobs."
From the third floor up, a Putzmeister 32Z-Meter boom (detached from a truck-mounted pump) and a MXR 32/36 separate placing boom are being utilized. The 32Z- and 36-Meter booms, with 92 ft. and 104 ft. horizontal reaches respectively, provide the required reach without the need to drag additional hoses. A Putzmeister BSA 14000 HP-D trailer pump with its powerful 510 hp diesel engine for maximum volume at long distances is also being used for the project.
Other Putzmeister equipment includes two 80 ft. placing boom towers on opposite ends of the building. The higher 80 ft. tower heights are required because of each deck’s wave, which required rebar to be erected at an exceptionally tall height that accounts for 30 ft. of the finished floor when pouring. Add on to that 50 ft. of tower needed outside the brace point. As a result, an 80 ft. tower is an absolute necessity.
Andy Paulazzo, vice president of Interstate Concrete Pumping comments, "We found Putzmeister to be the only manufacturer to offer an 80 ft. climbing tower that handles this particular application. And even with such a tall tower, we still could only do one level before we had to elevate again."
To raise the placing boom, an innovative inside climbing approach was specifically designed to fit the larger mechanical shafts and accommodate the peculiar way the rebar is being erected for the elevator core walls. Eric Peterson, project superintendent of Webcor Concrete Construction, engineered a special steel floor frame that bolts inside the elevator core and elevates with the boom, yet involves no hydraulics.
Peterson says, "Necessity is the mother of invention. Because there is literally no place to put a shaft, we are forced to use the larger mechanical ones already in place. We are making it work by constructing a special system of beams to support the tower and boom. All the equipment is performing exceptionally well."
Eight concrete pours per level are essential. For horizontal pours, the average output is approximately 230 yd/hr. For vertical pours, the average output ranges between 70 to 100 yd/hr. Altogether, it takes about two weeks to advance to the next level and start the construction process all over.
Although not specified for the project, Putzmeister’s 32Z-Meter unit offers an added benefit. Because its Z-boom features an unfolding configuration with a low working height, maneuvering and reaching under the tower cranes, which are just slightly overhead is easy.
In addition, the power of the Putzmeister BSA 14000 trailer pump and the experience of its operator, Robert Turner Sr., also prove especially note-worthy on site. The trailer pump is forced to pump concrete down a long winding path to a placing boom tower because the building’s plumbing prevented a more direct route. Under the guidance of Interstate Concrete Pumping’s highly seasoned operator, a maze of elbows literally circling the elevator core was assembled. It uses over 200 ft. of delivery line before going vertically another 100 ft.
Paulazzo says, “This was a highly unusual project with extremely congested site conditions, but thanks to the distinctive capabilities of the Putzmeister placing booms and towers, everything is working according to plan.” He adds, “We have found our placing booms to be in especially high demand within the San Francisco area. By year end, we will have four placing booms with plans to keep them busy.”
Combining over 60 years of experience, Paulazzo and his two partners, Shawn Slate and James Nolan, own Interstate Concrete Pumping. Started in 1996, the company today operates a 45-unit fleet from five locations throughout northern California. The company’s success in placing boom jobs is attributed to both ingenuity and attention to detail.
Paulazzo notes, “In addition to technical expertise, you need a lot of patience and imagination to effectively set up a placing boom system that meets site demands. If contractors have even one bad experience it can turn them off of ever using placing booms again. We can not afford to let that happen.”
When this project is complete, the new San Francisco Federal Office Building will be a 430,000 sq. ft. tower with special construction on the first two levels to accommodate potential seismic problems and terrorist bombs. In addition, a four-story 118,511 sq. ft. annex building will project from the tower. The facility will also feature a 470-space parking structure, a three-story sky garden, and a one-story daycare center all surrounded by a public garden and open space.
The placing booms are projected to handle over 200 pours, with concrete work finished by March 2005 and occupancy to follow soon after. Overall, the 590,000 sq. ft. building is designed to reduce energy costs by 45 percent and expected to save $500,000 per year in taxpayer dollars.
General Contractor: Dick Corp./Nibbi Bros./Morganti
Project Management: Hunt Construction Group, Inc.
Flatwork Concrete Contractor: Dolan Concrete – San Jose, CA
Vertical Concrete Contractor: Webcor Concrete Construction – Hayward, CA
Concrete Supplier: Bode Ready-Mix – San Francisco, CA
Pumping Contractor: Interstate Concrete Pumping – Hayward, CA
Equipment: Putzmeister 52Z-, 55-, and 58-Meter concrete boom pumps; 32Z-Meter detachable Putzmeister boom, Putzmeister MXR 32/36 separate placing boom, two PM towers, and a Putzmeister BSA 14000 HP-D trailer-mounter concrete pump