Burj Khalifa -- Conquering the World's Tallest Building

Putzmeister's specially designed BSA 14000 SHP-D reached a world record vertical concrete pumping height of 1,988 feet (606m) topping out Burj Khalifa, (previously known as Burj Dubai) the world's tallest building at 2,717 feet (828m) high, in the United Arab Emirates.

"This extreme pump height was possible due to the trust and cooperation developed between the Samsung-led team, the concrete supplier and pumping service for the project, Unimix, the local Putzmeister agent German Gulf Enterprises (GGE), as well as Putzmeister Concrete Pumps GmbH," says Christian Stirm, application engineer at Putzmeister's global headquarters in Aichtal, Germany.

Unimix first broke its own record with its BSA 14000 SHP-D trailer pump while on Burj Khalifa in May 2007 for reaching a conveying height of 1,483 feet (452m). Shortly after in August 2007 they reached 1,749 feet (533m), and then in November 2007, it broke the world record again by conveying to a height of 1,971 feet (601m). And in April 2008 they reached the current world record for vertical concrete pumping at a height of 1,988 feet (606m).

To achieve the concrete record-breaking height for the three-winged tower located in central Dubai, both Putzmeister Aichtal Works and GGE started preparations in early 2005.

Once on site, Unimix, deployed a carefully designed concrete placing system including two Putzmeister BSA 14000 SHP-D trailer-mounted concrete pumps and one BSA 14000 HP-D trailer-mounted concrete pump; a carefully engineered delivery line system; four non-ballasted stationary placing booms (three MX 28-4 T and one MX 32-4 T placing booms); and various truck-mounted boom pumps.

"We conducted extensive tests with the BSA 14000 HP-D pump and delivery line on site," says Stirm. "The tests were conducted with horizontally laid pipelines to simulate the pressure behavior and expected friction of the concrete in the pipeline based on concrete mixture breakdowns, as well as converting it to the high-rise pumping."

Putzmeister was faced with the challenge of creating a new, super high-pressure trailer pump, the BSA 14000 SHP-D, specifically for this project. The pump's frame and hopper were reinforced in order to withstand the enormous forces of the concrete mixtures. Other characteristics of the new pump include: adjusted S-Valves and S-Valve bearings for the expected pressures and a high-tech filter system.

BSA trailer pumps were combined to create one pump station for this project. The pumping station pumped approximately 5,826,920 cubic feet (165,000m3) of high-strength concrete during the 32 months of operation.

Three of the trailer pump delivery lines were connected to the three MX 28-4 T placing booms, which were secured on platforms of an auto-climbing formwork and stood on 52-foot-high (16m) tubular columns for the structure's wing sections.

Throughout the entire project, only high compressive strength concrete mixtures were used and pours were only done at night because of hot temperatures during the day. Concrete was chilled in the concrete plant prior to preparation and part of the water was replaced with shards of ice, allowing the concrete to be transferred at 82°F (28°C) (nighttime temperatures in Dubai usually reach 104°F) to the project site.

"Each batch of concrete was monitored and logged in the plant," comments Stirm. "Before transferring the concrete to the pumps, the temperature and flowability were checked regularly and sample cubes of the batches were poured to check pressure.

"Putzmeister engineers developed a unique delivery line system where the line's wear behavior, its compressive strength and routing throughout the structure was considered."

According to Stirm, the structure's 75,347 foot square (7,000m2) foundation was placed by numerous Putzmeister truck-mounted boom pumps. The foundation is supported by 200, five-foot (1.5m) diameter concrete piles for the core tower and 650 concrete piles for the tower's wing sections.