After a three-week trek by ship and 8,635 nautical miles (16,000 km), Associated Concrete Pumping’s (Associated) Putzmeister 70Z-Meter, the world’s largest truck-mounted concrete boom pump, arrived in San Diego harbor from Aichtal, Germany. Soon after its arrival, the “Juggernaut” as the pump is often referred to, took concrete placement to the extreme on the Oakland Touchdown (OTD) – Phase 1 section of the San Francisco – Oakland Bay Bridge project, helping to place 2,600 cubic yards of concrete (1,988 m³) of concrete, along with Associated’s 63Z- and 46Z-Meter boom pumps.

In 1989, a section of the East Span of the Bay Bridge was damaged during the 6.9 magnitude Loma Prieta earthquake. Following the earthquake, extensive studies were undertaken to determine whether California’s largest bridges were seismically safe. It was determined the entire Bay Bridge required a seismic retrofit, ultimately reinforcing and rebuilding each section of the bridge.

Work on the seismic retrofit of the bridge began in 2001, and in August 2008, MCM Construction (MCM), the general contractor on the OTD - Phase 1 section of the project, arrived on site and work quickly began.

Two phases comprise the OTD section. The first phase includes construction of approximately 1,000 feet (305 m) of the westbound approach roadway, from the toll plaza to the Skyway, as well as approximately 500 feet (152 m) of the structure for the eastbound roadway. The second phase includes finishing construction of the roadways.

“Once complete, the Oakland Touchdown will connect Interstate 80 in Oakland to the two new side-by-side roadway decks of the new East Span,” comments Bart Ney, State of California Department of Transportation’s (CalTrans) public information officer. “A new electrical substation will be built in addition to extensive relocation of underground utilities.

“For westbound drivers on Interstate 80, the Oakland Touchdown will be an introduction to the new East Span of the Bay Bridge, and for the eastbound drivers from San Francisco, it will guide them from the Skyway to the East Bay.”

In addition to the OTD, six other sections of the San Francisco-Oakland Bay Bridge are undergoing seismic retrofits, making the project the largest public works contract for CalTrans, the owner/developer of the project. The other six sections include the West Approach, West Span, Yerba Buena Island Transition Structure, SAS span, Skyway and East Span Demolition.

A “Juggernaut” of a Job

According to Greg Allen, project manager for MCM, everything about the San Francisco – Oakland Bay Bridge project is super-sized, including the OTD’s foundations, the design of the bridge itself, and the 70Z-Meter concrete pump.

“The foundations are 6 feet (2 m) in diameter, 170 feet (52 m) long and three-and-a-half inches thick (89 mm),” says Allen. “And the design of the bridge superstructure features a sloped soffit combined with deck cross falls which created challenging geometry control. To provide easier access for the boom pumps and other construction equipment on this project, a trestle was built between the eastbound and westbound roadways.

In addition, the eastbound and westbound roadways are both  40-feet (12 m) high by 80-feet (24 m) wide. The job required boom pumps that provided exceptional reach to pump and place the concrete for the stem and soffit sections of the OTD precisely where it needed to be.

“We chose Associated because of their notable reputation within the concrete construction industry and the capabilities of their wide range of innovative equipment,” comments Allen. “Given the size of the bridge and the other job site obstacles, we were looking forward to seeing how the world’s largest truck-mounted concrete boom pump would fare on this site.”

“What better way to initiate the 70Z manufacturing feat than have it pump and place concrete for a historic project like the San Francisco-Oakland Bay Bridge?” asks Mike Parigini, owner of Associated and the first 70 boom pump. During the design phase of the unit, Parigini was instrumental in providing useful customer feedback and input to Putzmeister.

The 70Z, along with Associated’s 63Z- and 46Z-Meter were on site for the 10-hour concrete pour for the OTD westbound roadway’s stems and soffits in January 2009. Although the 70Z has been on other jobs since arriving on U.S. soil, the San Francisco – Oakland Bay Bridge was the first big project that showcased its impressive technological features.

“We were definitely impressed all around with the performance of the 70Z on this pour, especially in terms of its reach and pumping capacity capabilities,” notes Allen.

“With the 70’s five-section Z-Fold boom, it’s all about its flexible 227-foot four-inch (69.3 m) vertical and 212-foot 11-inch (64.9 m) horizontal reach, and being able to get where you don’t have to drag any hose,” says Parigini. “We can deploy the boom in either a ‘Z’ position or an ‘A’-frame configuration. Concrete is very heavy, so to move it anywhere at any speed without using a lot of labor is a huge time and cost saver for all involved with the project. The unit’s 10 axles come off the ground to steady its 176,000-pound (79,832 kg) weight.”

“The combination of its reach and up to 210 cubic yards per hour (160 m³/hr) of volume output at 1,233 psi, the 70Z was able to pump and place a large amount of the total 2600 cubic yards (1988 m³) of concrete for this pour without having to move to different locations on site, which would have increased the amount of time the pour would have taken,” adds Allen.

“The 70Z features a modular bolt-on flatpack and Putzmeister’s exclusive free flow hydraulics which ensured continuous smooth pumping and a consistent concrete flow for this pour,” notes Parigini.

Parigini continues, “One of the biggest misconceptions about a boom pump of this size is that it’s not easily maneuverable on job sites, but really, it is. The 70Z has a 59-foot (18 m) outside turning radius which allowed us to easily navigate the unit around the restrictive job site.”

The unit was also designed to pass California’s strict “purple permit” weight requirements, which makes it fully licensed for the road.

“With the 70Z cleared to hit the road, we don’t have to worry about not being able to use the pump in only certain jurisdictions,” comments Parigini.

“Our five-section 63Z-Meter and 46Z-Meter teamed up with the 70 to get the job done,” notes Parigini. “The 63Z’s Z-Fold boom 203-foot nine-inch (62.10 m) vertical reach and 190-foot seven-inch (58.09 m) horizontal reach helped tremendously to keep the job moving smoothly, along with its up to 260 cubic yards per hour (200 m³/hr) volume output. The 46Z-Meter’s horizontal reach is 136 feet two inches (41.50m), and its vertical reach is 148 feet four inches (45.20 m).

The 63Z was on site previously to the January 19th pour pumping and placing concrete for the OTD – Phase 1 section.

According to Parigini, both the 70Z and 63Z-Meter concrete pumps feature Putzmeister’s Ergonic® system which allowed his operators to set parameters that control the boom, the pump and a variety of operational functions on the OTD project site. The system is easily accessible in the Modular Control Box (MCB) on the units.

“This technology includes the Ergonic Pump System,” explains Parigini. “This optimizes the pump and other functions and Ergonic Output Control, which reduces fuel consumption, wear, noise and adjusts the engine speed to the delivery rate. In addition, Ergonic Boom Control controls the boom, and Ergonic Tele Service can be used in case remote diagnosis is needed for fault codes. There is also an Ergonic Graphic Display, a three-inch square LCD screen on the MCB that indicates the unit’s hydraulic fluid temperature, operating hours, delivery pressure/delivery pressure limit and delivery rate/delivery rate limit.”

In addition to the super-sized characteristics of this project, the concrete mix that was pumped and placed by all three concrete pumps was unique as well. “The concrete mix was a low-shrinkage design with a high strength at 43 Mpa at 7 days,” says Ney.

The 70Z, 63Z and 46Z-Meter will be on and off the OTD section of the project for miscellaneous concrete needs. The OTD project is slated for completion in May 2010.

The 70Z’s 10 axles come off the ground to steady its 176,000-pound (79,832 kg) weight.

Together, Associated’s 70Z-, 63Z- and 46Z-Meter pumped and placed 2,600 cubic yards (1,988 m³), of concrete for the OTD – Phase 1 soffits and stems in 10 hours.

All three concrete pumps boasted impressive horizontal and vertical reaches as well as volume output capacity on site.

Associated’s 63Z- (in foreground) and 70Z (in background) both feature Putzmeister’s exclusive Ergonic® technology.

The 70Z has a 59-foot (18 m)  outside turning radius which allowed Associated to easily navigate the unit around the restrictive OTD job site.

The eastbound and westbound roadways of the OTD are both 40-feet (12 m) high by 80-feet (24 m) wide, so the job required boom pumps that provided exceptional reach to pump and place the concrete for the stem and soffit sections of the OTD precisely where it needed to be.