Issue link: http://digital.canadawide.com/i/177297
" BEBO arches are precast component bridging systems that provide great strength in relatively light concrete shell structures. Spans range from 3.66 metres to 31 metres, and are uniquely capable of ultra-lowprofile geometries, with span-to-rise ratios as low as 10 to one." BEBO, Red Deer, AB. Courtesy Armtec. Tim Kuhn, director of sales and marketing , Armtec North America. He adds that 56 per cent of Lafarge's research and development work is spent on investigating sustainability solutions. The Cement Association of Canada is also embarked on several sustainability initiatives. One is a series of seminars that was this fall presented at venues from Vancouver to St. John's that discussed advances in concrete's energy efficiency, recent industry innovations to reduce its environmental footprint, and how the use of concrete can help reduce a building's global warming potential by up to 70 per cent. Complete with case studies, the seminars looked at specific strategies for reducing energy consumption, reviewed life cycle assessment methodologies, and at concrete's performance based on an LCA study by the Massachusetts Institute of Technology (MIT). The CPCI's LCA work focuses on precast, while that of the CAC encompasses cast-in-place, comparing it to wood and steel, says Rick McGrath, director for codes and standards and engineered structures at CAC. The CAC is using US Department of Energy (DOE) benchmarks and EnergyPlus simulation software. Three types of structures were used for LCA analysis – the single-family unit, four-storey multi-residential, and 12-storey commercial. "Using concrete, the energy savings for a standard single-family home is five to eight per cent," says McGrath, who notes that the MIT study presents various LCA models. Some of the findings in MIT's interim report of December 2010, titled Life Cycle Assessment (LCA) of Buildings – Concrete Sustainability Hub, were unsurprising, like the fact that buildings in the U.S. still account for 39 per cent of the country's greenhouse gasses. Like the study for CPCI, the MIT study uses two cities – in this case, Phoenix as the instance of a hot climate, and Chicago representing the cold one. Comparing the two cities, the study says that added thermal mass due to the use of concrete construction over steel construction provides annual energy savings of six per cent in Phoenix and five per cent in Chicago. Nothing very dramatic there, either. But another of MIT 's findings might prove a convincing sales closer for those promoting concrete in a cold climate. "For residential buildings, insulated concrete form Concrete p24-33Concrete.indd 27 construction (ICF) can offer operational energy savings of 20 per cent or more compared to code-compliant wood-framed buildings in a cold climate like Chicago," the study reports. Echoing the findings of the MIT study, in the practical world, the difference in R value between windows, curtain wall and a good concrete cladding system stands out in stark relief. Compare the R value of even the highest-end windows and an insulated concrete panel system and the difference is impossible to miss. Noting that a typical window has an R value in the two to four range, Malcolm Hachborn, chief engineer at Res Precast Inc., points to the fact that the insulated conncrete panels his company makes have R values in the 20 to 30 range. Also, he says, "The thermal mass of concrete is often ignored. It's hard to quantify." With Styrofoam insulation rated at about R5 per inch, it is not hard to see how cladding of insulated concrete panels cold reduces energy consumption in a cold climate. A panel can be up to 16 inches thick. "With two wythes of concrete on either side of the insulation your entire wall is in place except for the interior finish. The exterior wythe of concrete come with its textured finish and colour. The ties for the wythes go through the insulation – about one every four square feet. The specifier can indicate what material to use for the tie. The big advantage is that it's quick to erect – eight panels a day. That's 3,000 square feet of cladding per day," says Hachborn. Recently, the company has provided panels for hospitals, government buildings and some large commercial projects. Four-inch insulation is common for hospitals, he says, but a project in Oakville is being built with six-inch insulation to compensate for the lower R value of windows. Measures are being adopted to improve the longevity on concrete. "There's more use of non-ferrous reinforcing materials like fibreglass, basaltic reinforcing and carbon fibre," says Hachborn. He says that, starting sometime next year, the Ontario government is prohibiting the use of epoxycoated steel reinforcing on its projects. The province has previously set out regulations to help protect the coating in the field. No wonder. Corrosion of steel reinforcing is generally regarded as the main source of bridge deterioration. The use of ultra-high-strength concrete products like Ductal is on the rise – for panels, cladding and bridge deck slabs. "Ductal's price has been a stumbling block. But the price has dropped around 25 per cent in the last two or three years and it's likely dropping some more," Hachborn says. Marking another development on the sustainability front, Lehigh Cement, a division of Lehigh Hanson Materials Ltd., will no longer be providing GU (general use) cement as of January 2013 in regions like B.C.'s Lower Mainland, says Brad Pope, manager of fly ash and technical services at Lehigh. "The standard is now PLC, which has a greener footprint and sold under the Lehigh brand of EcoCem," he says. But in sulphate environments like like Kamloops and Kelowna, where sulphate-resistant cement is required, the company will sell a GU-plus-fly-ash blend or Type 50 sulphate-resistant Portland cement. A University of Toronto study is underway to further understand PLC's performance in sulphate environments. One of Lehigh's products, InterCem, is a new cement that's designed to provide superior strength in high sulphate environments like much of the prairie regions. "It's the degree of sulphate in the soils that dictate the measures that must be taken," Pope says. Innovations in crane technology and the growth in size of mobile cranes are affecting a niche area of the concrete sector. Mardina Construction Ltd. does a lot of tilt-up construction and is seeing some improved efficiencies as the potential size and weight of panels increase. "The industry is evolving as they keep coming up with bigger mobile cranes, so bigger panels are now possible. In B.C., a 500-tonne mobile allows for a 200,000-pound panel," says Casey Klaassen, owner of Mardina Construction. But in regions where some sectors within the industry have seen activity slow or are on the brink of contraction, costs, not innovation, are likely more of a priority. In Ontario, larger companies in the concrete sector like Structform International Ltd., are weathering the current conditions, but some smaller and medium-size firms are hard-pressed to find suitable projects. Less of a boon to smaller firms, several big hospital and transportation projects have helped maintain activity levels at companies like Structform. december 2012 /27 11/16/12 3:22 PM