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DECEMBER 2017 | 11 Concrete PHOTOGRAPHY COURTESY ARMTEC C Concrete has become the material of choice for design expression by ROBIN BRUNET On Full Form Concrete is the undisputed, ultimate material for tra- ditional building techniques; but developments such as decorative and light-transmitting concrete, as well as advances in finishings, admixtures and other realms, have taken it far beyond its established abilities. The many subdivisions within the concrete category (cement and cast-in-place; precast and prestressed; additives/admixtures; finishing and staining; and engi- neering and testing) are all experiencing growth. Brian Hall, managing director, Canadian Precast Prestressed Concrete Institute (CPCI), says that times are definitely changing and total precast building solu- tions are now becoming a popular choice for many con- struction projects. "Speed is one of the defining characteristic of a very efficient construction process," says Hall. "The precast concrete industry has made significant advances in implementing prefabrication processes and materials to build and deliver more sophisticated and complex facility types." The industry is seeing an increasing number of customers turning to prefabrication for multi-storey buildings, health care facilities, educational structures and large apartment/condo projects. Always known for its time-saving advantages, precast concrete pre- fabrication is now recognized as a more resource-effi- cient, greener process. "Because the concept of productivity can be diffi- cult to define, measure and communicate, the National Research Council has defined efficiency as ways to cut waste, time, costs, materials, energy and labour to produce more environmentally sustainable projects," explains Hall. Throughout Canada there are many total precast concrete projects being built and many more projects being constructed. On many of these projects, total precast concrete has taken months, even years off the project time schedule. Lafarge Canada Inc. is a good example of a con- crete manufacturer with a huge portfolio of current and recently finished projects. This year saw the com- pletion of Brookfield Place, a 58-storey full block com- mercial development located in downtown Calgary. For the construction of this mixed-use facility, a highly f lowable and non-segregating concrete mix was required, with the pumping height during final phases of construction being 247 metres vertically for the east tower. Additionally, the concrete had to be capable of achieving full consolidation in complex areas, with dense steel reinforcement for the core of the structure. The Lafarge solution for Brookfield Place was an Agilia concrete mix from its ready-mix portfolio, which not only provided self compacting concrete for the dense steel reinforcement but also achieved 12 megapascals (MPa) at 18 hours for early stripping – that in turn allowed contractors EllisDon to maintain their construction schedule. Altogether, 58 storeys of core work totalling 25,840 cubic metres of Agilia was poured from October 2014 to May 2016. Of course, Lafarge is no stranger to daunting on- site challenges. Calgary City Centre is one of that city's newer iconic high-rise towers, and in order to condense construction time for that project, PCL Construction Management needed a high early strength concrete mix that could reach 30 MPa within 48 hours for the foundation, core, columns and slab work. Lafarge provided PCL with Chronolia 48H, a propri- etary high early strength concrete mix that achieved the specified MPa in the time needed. In addition to Chronolia, Lafarge also supplied Agilia Vertical to further help PCL accelerate their schedule. About 3,900 cubic metres of Agilia was used for columns in the parkade and suspended floors, and 15,500 cubic metres of Chronolia for 36 floors of suspended slabs was poured over a two year period; the simultaneous Graphic Concrete technology, available exclusively in North America through Altus Group precasters.

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