Caltrans announced that it is approving the use of low-carbon cement to help reduce the carbon footprint of California’s transportation system. By advancing the use of Portland Limestone Cement (PLC), Caltrans’ road construction and maintenance projects can generate less carbon dioxide – the primary greenhouse gas contributing to global warming and climate change – with the same high performance standards at a slightly lower cost.

“Using low-carbon cement can cut Caltrans’ concrete-related carbon dioxide emissions annually by up to 10 percent,” said Caltrans Director Toks Omishakin. “This is a big step in supporting California’s efforts to achieve carbon neutrality by 2045.”

Cement is typically produced by mining, grinding, and heating limestone in industrial kilns to temperatures as high as 2,820 degrees Fahrenheit (1,550 degrees Celsius). The process alters the rock’s chemistry and creates “clinker” – the basic component in nearly all types of cement – but also generates large quantities of carbon dioxide. PLC contains less clinker.

In 2017 alone, Caltrans used 325,000 tons of cement to upgrade the state highway system. Switching to low-carbon cement has the potential to reduce carbon dioxide emissions by 28,000 tons a year – the equivalent of removing more than 6,000 cars off the road.

Caltrans expects that the reduced energy needs associated with PLC production will make the cost similar or slightly less when compared to regular cement.

The new low-carbon cement standards are based on Caltrans-funded research conducted at Oregon State University, which concluded that PLC is equally suitable for Caltrans’ construction projects as ordinary cement with a reduced carbon footprint. Throughout the review process, Caltrans worked closely with its partners at the California Air Resources Board and industry experts and stakeholders, such as the California Construction and Industrial Materials Association and the California Nevada Cement Association, to draft the new standard specifications.

In 2010, Caltrans changed its concrete standard specifications to increase the use of sustainable alternatives in transportation projects, an initiative that helped spur a shift in concrete production throughout the state. Caltrans will continue to work with the California Air Resources Board to reach the state’s goal and achieve net-zero emissions from the cement sector by 2045.