In an effort to promote innovative and sustainable construction solutions, U of T Engineering, along with the Ministry of Transportation of Ontario (MTO) and Holcim (Canada) Inc. recently partnered to perform the first public agency trial of a concrete pavement section using a new class of cement called Portland limestone cement (PLC).
PLC has strong environmental and sustainable construction benefits. The manufacturing of PLC generates significantly lower greenhouse gas emissions and up to 10 per cent fewer carbon dioxide emissions as up to 15 per cent of the clinker used to produce regular Portland cement is replaced by limestone. The concrete produced with PLC is as strong and durable as concrete made with regular Portland cement.
Based on proposals from Holcim Canada, the ministry carried out two trials on existing Central Region contracts utilizing PLC. The first trial used PLC in a cast-in-place concrete barrier wall section, located on the westbound QEW between Brant Street and Burloak Drive.
With the favourable outcome of this trial, a second trial was performed on September 2010 using PLC in slipformed concrete pavement on an exit lane to Hurontario Street of Highway 401 eastbound. Both trials represented the first field applications of the new cement in structural and pavement applications by a public agency in Canada.
The Department of Civil Engineering played an instrumental role in testing this concrete and will be monitoring the trial sections over the next three years to gain valuable insight into field performance.
According to Professor Doug Hooton, who also holds the Industrial Research Chair in Concrete Durability and Sustainability, “The concretes being used by Holcim Canada in this contract had already resulted in approximately a 24-per-cent reduction in carbon dioxide emissions relative to plain Portland cement concrete by using GranCem, a slag-based product.
“In this trial section, PLC has been used in combination with GranCem and the carbon dioxide emissions are reduced by 33 per cent compared to plain Portland cement concrete without any anticipated impact on concrete properties or durability. The co-operation with MTO in allowing this important trial shows the ministry’s commitment to adoption of innovative changes to improve green house gas emissions associated with new infrastructure.”
“Although relatively new to Canada, PLC has been used in Europe for over 25 years,” said Paul Ostrander, president and CEO of Holcim Canada. “Holcim Canada’s cement plants in Mississauga, Ont., and Joliette, Que., currently manufacture PLC for trials in Ontario and Quebec. Moving forward, PLC will also qualify for LEED® credits.”
“This is a great example of an industry-academia collaboration that can have significant impacts on the sustainability of our cities,” said Professor Brenda McCabe, Chair of the Department of Civil Engineering. “Just consider the amount of concrete in our infrastructure.”
