Sources: Portland Cement Association, Washington, D.C.; CP staff
Recent portland-limestone cement (PLC) approvals by the Arizona and Maryland Departments of Transportation, plus the Vermont Agency of Transportation, bring to 44 the total of state authorities recognizing the material in specifications for concrete pavement, bridge and other structures. The approvals will accelerate a Portland Cement Association-tracked PLC consumption trajectory eclipsing 6 million metric tons to date.
Most commonly designated as Type IL cement and produced to meet ASTM C595, Standard Specification for Blended Hydraulic Cements, PLC bears 5 percent to 15 percent ground, uncalcined limestone blended and/or interground with clinker and other additives. The finished powder offers similar performance to traditional portland cement but has a carbon dioxide emissions factor up to 10 percent lower. Engineers and concrete practitioners use PLC as a one-to-one substitute for ASTM C150 Type I/II portlacent cement, coupled with the same volumes or dosages of supplementary cementitious materials and chemical admixtures. State DOTs indicate PLC acceptance by adding language to their specifications such that use of ASTM C595 Type IL is an alternative to other acceptable cement types, namely ASTM C150 Type I/II.
Use of PLC for transportation and all other concrete applications has been steadily increasing since October 2020, when PCA formally introduced www.greenercement.com to raise awareness and educate specifiers, builders and other users about the material’s performance and environmental benefits.