Issue link: http://digital.canadawide.com/i/607779
DECEMBER 2015 | 13 PHOTOGRAPHY COURTESY LAFARGE NORTH AMERICA Concrete Could the concrete sector be on the cusp of a transformation? by GODFREY BUDD Mix It Up C Concrete is the single most widely used manufactured material on earth. Concrete's almost ubiquitous avail- ability, versatility, strength, fire-resistance, low-main- tenance requirements and affordability has a lot to do with its popularity. Concrete gains strength over time and is not weakened by moisture, mould or pests. Perhaps most importantly, concrete lasts. "Roman buildings over 1,500 years old such as the Colosseum are living examples of the strength and durability of concrete," according to a study by the World Business Council Sustainable Development. The Pantheon in Rome, completed for the emperor Hadrian around AD 128, is perhaps an even better example of concrete's capacity for longevity, for, unlike the Colosseum, it is still standing in its entirety. The dome's interior diameter is 43.3 metres, the same as the distance from floor to oculus. The Pantheon still holds the record for the world's biggest non-reinforced concrete dome. After falling into disuse for almost a millennium following the collapse of the Roman empire, tech- niques for cement and concrete were revived during the Renaissance. It could be said, however, that the modern age of cement and concrete technology truly arrived only in the 19th century. Joseph Aspdin pat- ented a method for making Portland cement in 1824 and Joseph Monier invented reinforced concrete in 1849. Both were game-changers. The concrete sector, with its techniques going back centuries, can give the impression that, technology- wise, not much changes. But the world's most widely used building material could be on the cusp of another transformation. Concrete can be improved and its carbon foot- print reduced by paying more attention to its atomic structure, according to scientists at Rice University, the Massachusetts Institute of Technology (MIT) and Marseille Universit y. A 2014 study entitled Combinatorial Molecular Optimization Of Cement Hydrates found that at any given calcium/silicon ratio, there may be 10 to 20 different molecular shapes, each with distinct mechanical properties. The inter- national team of scientists behind the open-access paper have developed a kind of "genome" of cement and concrete, and created computational models to help concrete manufacturers fine-tune mixes for gen- eral applications. The Solidia system from Solidia Technologies, uses carbon dioxide (CO2) in the curing process and is also expected to reduce the carbon footprint of concrete. Some see it as potentially transformational. Over the last year or so, Lafarge North America's precast divi- sion ran a series of trials in preparation for commercial production using the Solidia process. The company's Edmonton plant will manufacture hollowcore floor slabs and architectural wall panels. "We're scaling up production of Solidia. I expect full-scale production with Solidia within a few months. We'll bring in CO2 from various sources. When volumes get going, it will sort itself out. We'll scrub the stack from cement-mak- ing," says Don Zakariasen, director of marketing con- crete products at Lafarge North America. "Solidia has a role in the new energy code require- ment of R27. It enables a thinner wall system as well as reducing the carbon footprint," says Zakariasen, noting that Lafarge is partnering with Dow Chemical Company, which makes insulation, to provide sand- wich insulated concrete panels. The recent technical and scientific developments in cement and concrete could herald a quantum leap in both improving concrete's performance and reducing its car- bon footprint. The industry's commitment to reducing greenhouse gases (GHG), however, goes back at least two decades when cement manufacturers started investing in pre-heater towers to recover waste heat, says Adam Auer, director of sustainability and stakeholder relations at the Cement Association of Canada. Today, Auer says, there are two main strategies for curbing GHGs. One is to substitute fossil fuels with low carbon ones or renewables. Another involves cut- ting the amount of clinker in cement, and cement in concrete. "The second strategy is where architects, engineers and planners can play an important role in reducing the embodied CO2 of their projects by speci- fying low clinker cement as well as mix designs that maximize cement substitution in accordance with required performance specifications. In fact, cement substitution with by-products of other industrial pro- cesses, for example, fly ash, slag and silica fume, can + Hollowcore floor slabs using the Solidia process manufactured by Lafarge North America.