Sources: Holcim Canada, Mississauga, Ontario; CP staff
On the heels of Canadian Standards Association approval and National Building Code of Canada reference, a new class of portland-limestone cement (PLC) has been recognized in Ontario and Quebec building codes as an alternative to ASTM C150-equivalent or CSA General Use powder.
Holcim Canada’s Mississauga flagship and Joliette, Quebec, plants have been supplying PLC—milled with up to 15 percent ground limestone, versus a prior 5 percent limit—to ready mixed and precast producers in both provinces for trial production. Production of the new cement is expected to reduce the plants’ annual carbon dioxide emissions by 130,000 tonnes. PLC exhibits strength development performance comparable to GU cement, Holcim Canada notes, and can be used with supplementary binders at volumes to which concrete practitioners have become accustomed.
Ontario Building Code referencing of PLC, notes Holcim Canada CEO Paul Ostrander, “enables us to provide [customers] more sustainable construction solutions. PLC produces a concrete as strong and durable as that made with regular General Use cement.” Production generates significantly lower greenhouse gas emissions and up to 10 percent fewer CO2 emissions against GU cement milling, he adds, noting that Holcim Canada will pursue PLC recognition in the LEED building rating system.
The Ministry of Transportation of Ontario effected PLC mix trials on Central Region contracts last year: a cast-in-place barrier wall section along a major highway stretch in Burlington and a slipformed pavement in Mississauga on a Highway 401 exit lane. The trials represented the first field applications of the new cement in structural and pavement applications by a Canadian agency.