Rising in Houston’s uptown district with scheduled fall 2016 occupancy, the 600,000-sq.-ft., 30-story BHP Billiton Tower is earmarked for LEED Gold Certification and will occupy a 2.4-acre tract. The reinforced concrete structure is 100 percent preleased to the global energy and resources subsidiary of Australia’s BHP Billiton Group.
Site work began in October 2013 under Houston general contractor Harvey Builders. The concrete phase kicked off in February with a continuous, 11-hour mat pour, led by Hi-Tech Concrete Pumping Services, concrete contractor Texas A&M Concrete LLC, and ready mixed supplier Argos USA. To accommodate the congested Galleria area and not overextend hours for Argos mixer drivers, the pour occurred on a weekend night. With limited set up points to access an irregular, five-sided foundation in close proximity to a street, Hi-Tech turned to six larger Putzmeister truck-mounted concrete boom pumps—targeted for their long boom reaches and output up to 260 yd./hour.
Hi-Tech perched a 46X model on level ground at the top of a ramp, the boom extending about 135 feet to pump concrete directly into the deck pipe of a 52Z, positioned on a specially prepped area in a 30-ft. deep hole. The 52Z had plenty of reach, extending its boom out 157.5 feet horizontally to place concrete without additional delivery line. The arrangement meant mixer trucks would not be forced to negotiate a ramp in and out of the hole, and kept the pour progressing at a faster pace.
The other four pumps were located on the only two sides of the excavation available for setup, with a 63Z situated to reach the farthest point about 200 feet away. A spider web of booms extended into the hole, conveying mixes for a mat of 5- to 10-ft. thickness. After eight-and-a-half hours, pumps began to leave as they finished their area of coverage. The last unit left the jobsite after 11 hours, marking 7,700 yd. of concrete placed.
The tower’s lower levels up to the third floor were placed with different truck-mounted boom pump sizes from Hi-Tech’s 26-unit fleet. A Putzmeister BSA 2110 HP-D high pressure trailer pump in combination with MX 36/40Z separate placing boom took over to handle concrete placement to the top floor. When installing the placing boom, there were issues about the pipeline going straight up as it would interfere with interior work that needed to be accomplished on certain floors.
Hi-Tech devised a special pipeline route involving a zigzag approach with vertical and horizontal runs of 5-in. pipe plus four thrust blocks. Initially, pipeline would travel up three floors; it would then run across the next floor at a distance of 80 feet before it traveled upward again to the tower and boom assembly.
Capable of a 115-ft. reach, the placing boom is mounted on a 70-ft. Putzmeister bolt tower, which was set up in a strategic location, again not to interfere with other trades. The placing boom, without the need for counterweight, along with the tower are lightweight enough to be raised together by a tower crane from one level to the next, resulting in a fast and efficient lifting process. — Putzmeister America, 800/ 884-7210; www.putzmeisteramerica.com