Being able to put fresh concrete where you want it when you want it, abruptly changing the length or direction of flow, is often critical in concrete pumping operations. Today, changes in flow need not be done entirely by brute strength. Good job planning and the use of modern equipment accessories can make concrete pumping operations as streamlined as those of a well-run factory. Two examples of good planning are the systematic layout of pipelines with frequent valving and the use of placing booms. These methods were used on a big job: construction of a nuclear power plant at Clinton, Illinois. The 950-megawatt plant had a large materials list, including 300,600 cubic yards of concrete, 3,175,000 square feet of forms and 4,330,000 pounds of embedded metal. These materials were used in construction of a 0.65-acre concrete slab varying from 9.67 to 14.67 feet in thickness, a containment building with walls 3 feet thick, 130 feet in diameter and 213 feet high, a concrete reactor vessel wall and other structures. In planning this job, the prime contractor realized that pumping would be the best way to place the huge volumes of concrete needed.
USE OF PLACING BOOMS
Early in the job planners concluded that separate placing booms fed by concrete pumps located outside the work areas would be ideal for placing concrete in columns and slabs of buildings other than the containment building, especially those with large area placements. This method would cost less than conveyor or crane boom and bucket. Piping could be laid from a pump to a placing boom without obstructing other work. Also, a placing boom only takes two men, one at the tower control and one handling the discharge hose. Two placing booms and three boom pedestals were used on the Clinton job. While two booms were working the third pedestal could be relocated to the site of the next placement.