Portland limestone cement: reducing greenhouse gas emissions
As project owners raise their expectations for greener, environmentally sound construction practices, portland-limestone cement (PLC) offers pavement contractors an option to meet expectations while maintaining high strength and quality standards. PLC is a cement with up to 15% limestone content, which results in a reduction of greenhouse gas emissions by an average of 10–12%.
“We’ve been using PLC in trials, demonstration projects, and full-scale projects for about 15 years and found that it works equally as well as portland cement,” says Jason Weiss, Ph.D., Professor of Civil and Construction Engineering at Oregon State University. Designed as a direct substitute for portland cement, the use of PLC is not disruptive to a contractor’s normal operations. “A slight adjustment to admixtures may be needed, but other than that, no changes in operations or equipment are required.”
In 2018, only 27 state transportation agencies had standards that allowed PLC use. As of February 2022, the number has grown, with only six state agencies not yet having approved the use of PLC. This widespread acceptance of the product will increase manufacturers’ ability to produce PLC for more markets. “There is only a certain amount of storage space, so many cement producers will only produce one type of cement at a plant,” Weiss said. “As demand for the product grows, so will supply.”
In addition to reducing the carbon footprint of concrete pavement, the production of PLC has the added benefit of extending the life of quarries, said Weiss. The broad focus on sustainability and a need to better use resources will continue to drive the use of PLC in concrete pavement.
“I estimate that in a few years, PLC will be the dominant cement used in the United States,” says Weiss.