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Sustainability especially when several patches throughout the structure require The site was located in the middle of the St. Lawrence River, repair. Through the use of the shotcrete process, a nozzleman 5 miles (8 km) from the coast of Tadoussac, QC, Canada, and was and finisher can shoot, cut, finish, and cure several patches in only accessible by barge and only when the weather was coop- succession, without having to return to the same location on the erative. Shotcrete nozzlemen worked from an inflatable zodiac, structure. This results in lower labor costs and a reduced construc- with all material, equipment, potable water, and other personnel tion schedule. The shotcrete process also allows the contractor to located on the main barge. The shotcrete was placed ahead of stage materials and equipment from one central location, accessing the rising tides through a 490 ft (149 m) long hose that ran from several repair areas from that location, thereby minimizing the barge to the zodiac. The shotcrete process allowed easier movement, planning, and time necessary to shift operations. access to the site and eliminated any need for forms. It played a significant role in the successful completion of this project. Access in Remote or Isolated Environments Concrete placement challenges can also come from projects Access in Challenging Terrains where access to the project itself is the biggest challenge. Repairs Whether selecting a wet or dry shotcrete process, it is much to an isolated lighthouse and construction of a remote dam are easier for a nozzleman to reach a difficult-to-access placement two examples. For these types of projects, a lack of proximity site while the crew, material, and equipment are stationed in to a batch plant, cement supply, and aggregate source generally an accessible location. Difficult access, however, can mean makes pre-blended, pre-bagged materials the best choice for different things to different people. The location of a backyard material supply. As with other projects where access is a chal- swimming pool, for example, can be considered a difficult-to- lenge, the less formwork required, the more efficient the concrete access location for the pumps and other materials supply placement process will be. When the Haut-fond Prince Light- equipment. Other examples of difficult access can be much house rehabilitation was tendered in 1996, shotcrete was more extreme and include projects that require skilled noz- specified as the placement method and a highly accelerated, zlemen who are also skilled rock climbers. durable, steel-fiber shotcrete mixture, supplied in lined marine An example of the latter occurred in 2003, when New Jersey tote bags, was specified for the material supply (refer to Fig. 4). Transit was faced with the challenge of stabilizing the rock Fig. 2: The rehabilitation of elevated bridge structures is a Fig. 3: On elevated structures, forms and form hardware common example of an application where the shotcrete must be lifted into place and removed several days later process can minimize the problems related to access 62 Shotcrete • Summer 2013


2013SumShotcreteEMag
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