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The Agrium on the Calgary Stampede Park grounds featuring load bearing precast concrete insulated sandwich panels from Lafarge Canada Ltd. AUGUST 2016 | 13 Building Envelope PHOTOGRAPHY BY TUCKER PHOTOGRAPHY/COURTESY LAFARGE CANADA INC. T Ancient technologies and modern innovation marry for building envelope excellence by GODFREY BUDD The series of choices and decisions that underpin the design of building envelopes and the structures that support them are inevitably informed by the project's key objectives and the available products on the mar- ket. But if whole-life cost considerations and durability register high on the list of priorities, precast concrete panels for the envelope cladding system could well be the best bet, according to a study from consultancy Hanscomb Limited. Its 805-page report, submitted to the Canadian Precast Prestressed Concrete Institute (CPCI) on March 31, found that, "For the commercial projects with the cladding models we reviewed, any of the pre- cast concrete cladding systems generally had the best overall cost performance with any structural sys- tem for the whole-life cost for an average location in Canada. Second was the curtainwall cladding system while the brick veneer cladding system on a precast concrete structure was rated a close third." For multi-residential projects, precast cladding panels also scored the highest on cost performance, followed by brick veneer on a precast concrete struc- ture, then curtainwall. For whole-life cost, the study factored in a range of costs including construction, warranty, financing, health, social, deconstruction, new energy code premium and savings, and operation and maintenance over 73 years. "The study looked at a wide range of assembly types in nine cities across the country," says Brian Hall, managing director at CPCI. To do its comparative analysis of various cladding and structural systems, Hanscomb selected a sample project constructed in Fort McMurray around 2006 with the most common building, a six-storey multi- family rectangular structure of 150,000 square feet plus a single level of underground parking. Its dimen- sions are also typical of many commercial and retail buildings across Canada. "Being six storeys, the sample of a building model will be able to include all the most popular structural building systems being used in Canada today, including wood frame," the report says. "The choice of sample allowed the study to select from a wide variety of model structure and cladding systems to develop its comparative matrix," Hall adds. A new type of cement called Solidia should soon dramatically boost the appeal of precast concrete products, including those used for envelope cladding systems. Solidia cement is now approaching more widespread commercialization. Using the same raw materials, but a new proprietary process, it can be made in a typical Portland cement plant, but with less lime, a lower kiln temperature and about 30 per cent less energy and emissions. Its rapid curing process, which involves adding car- bon dioxide (CO2) to the cement, sand and water mix, should make it a game-changer in the precast concrete sector. Instead of taking about 28 days, Solidia con- crete cures in about 24 hours. "In May this year, at our Edmonton plant, we had the first commercial Lafarge precast production with Solidia. At the end of the day, we made a commercially viable product. We will be subjecting the product to a series of tests," says Don Zakariasen, director of marketing, concrete products, at Lafarge, a member of LafargeHolcim. Lafarge has a partnership agreement with New Jersey-based Solidia Technologies to do industrial devel- opment and global distribution of Solidia products. Besides hollowcore, produced at the Edmonton plant, it is expected that Solidia-based precast prod- ucts have an excellent future in the precast cladding sector – and not just because of the rapid curing speed and diminished environmental footprint. "Solidia con- crete is more compatible with glass fibre reinforce- ment [GFR]. Unlike conventional concrete, it won't react with glass fibres, so they don't have to be coated with something first," Zakariasen says. Besides scalable, disruptive technologies from the Garden State, more stringent Canadian energy codes are also spurring changes to insulated precast StampOf Approval

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