The California Department of Transportation (Caltrans) recently approved the use of low-carbon cement in the state’s transportation system.
The use of the cement will generate less carbon dioxide at a slightly lower cost than traditional cement. Performance standards are the same.
Traditional cement is produced by mining, grinding, and heating limestone in industrial kilns to temperatures as high as 2,820 degrees Fahrenheit. Heating alters the rock’s chemistry and creates “clinker,” the basic component in nearly all types of cement. The process also produces large quantities of carbon dioxide.
Portland limestone cement (PLC) contains less clinker.
Caltrans used 325,000 tons of cement to upgrade the state highway system in 2017 alone. It is estimated that switching to PLC could reduce carbon dioxide emissions by 28,000 tons annually.
Caltrans-funded research conducted at Oregon State University found PLC is suitable for Caltrans’ construction projects.
The agency worked with the California Air Resources Board during the review process as well as 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.
Caltrans changed its concrete standard specifications in 2010 to increase the use of sustainable alternatives in transportation projects.