When its expansion is complete, Complexe Jules-Dallaire, owned by Cominar Real Estate Investment Trust and located in Quebec City, Canada, will be one of the tallest buildings in the city. To help Phase Two of the project reach its full height under challenging conditions, the construction team employed a Putzmeister detach truck-mounted concrete boom pump and other equipment, marking the first time a concrete pump and placing boom was used on a high-rise building in Quebec City.
Phase One of Complexe Jules-Dallaire, which was completed in 2010, included the construction of two towers joined by a central section. One tower was built up to 17 floors, the maximum height allowed by the city of Quebec at that time, while the second tower had not yet been started. The scope of the $80 million Phase Two of the project, which began in September 2011, consists of adding the second tower to the structure, which when completed will reach 29 floors.
Frédéric Gauthier, engineer and project manager with the project's general contractor, Dalcon Inc., enlisted the expertise of the local Putzmeister distributor, Pumpaction Inc., and its sales representative, Keith Armishaw, to help him choose the proper equipment needed to deliver the more than 19,600 cubic yards (14,985m3) of concrete required to reach the maximum height of 361 feet (110 meters) for this project, which is scheduled for completion in late 2013.
Providing enough pressure to place concrete at a height of 361 feet can be a challenge if the proper equipment is not used. To help overcome that challenge, the construction team chose to use a 38Z-Meter truck-mounted concrete boom pump. It is equipped with the optional Series II detachable boom and SBU conversion kit, as well as a high-pressure hopper and outlet to handle the higher pressure.
"We chose these options for this particular project because the calculated pressure required by the end of the job would be greater than the standard 1233 psi (85 Bar) pressure of the Putzmeister 16 cell pump system," says Armishaw. "The SBU conversion was used to quickly convert the pump from rod side to piston side oil supply."
In addition to pressure at that height being a challenge, managing the pouring schedule on a high-rise project can also be difficult. For this job, each elevated floor slab is being placed in two parts. Once the first half of each floor is ready for concrete, approximately 273 cubic yards (250m3) are poured for that section of the floor. Then, columns are poured, along with the second half of the floor. The process of pouring the entire floor level takes from one to two weeks, with weather being a factor in the planning and pouring schedule.
Weathering the Storms
Receiving more than 10 feet (three meters) of snow annually, Quebec City provides a challenging environment for construction; snow, ice and wind can have a tremendous impact on schedule and equipment.
In addition, contractors need to adhere to strict frost law requirements for tandem axle vehicles. The maximum allowable weight is 53,274 pounds (16,000kg) on the front axle and 33,069 pounds (15,500kg) on the rear axle during the thaw period. To accommodate this requirement, the pump is mounted on a twin steer extended chassis.
"Having the option to choose the twin steer chassis was a huge advantage to us in terms of schedule," says Gauthier. "It allowed us to work throughout the frost thaw period in compliance with regulations."
Special consideration also needs to be taken to keep the exposed concrete delivery line, which measures approximately 200 feet (61 meters), heated during the winter months. Otherwise, the concrete could freeze in the pipe, resulting in massive schedule delays and significant labor and materials costs. To do this, the contractor is using heat trace wire and is insulating the delivery line. Insulation is also being used on the boom pipe to prevent it from freezing.