GCC Presents Insights on PLC at ACPA's Excellence in Airfield Paving Workshop

During the American Concrete Pavement Association Excellence in Airfield Paving Workshop held in Denver from October 24 to 26, experts from our technical services team shared GCC’s experiences shifting our plants and customers to Portland Limestone Cement (PLC).

Urs Fuchs (Fox) ,Technical Services Manager, and Anne Miller , Quality Manager for GCC’s Pueblo Plant, gave a brief overview of PLC in terms of its strength, setting time, fineness and particle size distribution, water demand, workability, heat of hydration, scaling and freeze thaw resistance, and sulfate resistance.

They then facilitated an engaging discussion regarding PLC manufacturing processes and quality control measures, focusing on providing answers to why the same PLC cements from different plants are different. Fox and Miller explained that PLC products vary slightly between manufacturers depending on the plant’s local geography, available raw materials, fuel mixtures, pyro-process (kiln, preheater, pre-calciner), and finish grinding technology.

Although early and late concrete compressive strengths are similar, there are some performance differences between traditional Ordinary Portland Cement (OPC) and PLC, just as there are differences between PLCs from different cement suppliers. Therefore, to maximize the performance of finished concrete, it is critical to perform mix design and field tests when using PLC.

Fox noted that admixtures should be carefully evaluated based on individual merits and desired outcomes. He elaborated on the critical importance of matching lab and field test conditions such as temperature, and he gave practical recommendations for improved PLC performance.

In closing, Fox and Miller presented the benefits of PLC in terms of the fast-moving, industry-wide push toward sustainability. They cited that if all cement used in the U.S. in 2019 had been converted to PLC (Type IL), it would have reduced CO2 emissions by 8.1 million metric tons. The U.S. EPA says this figure represents the equivalent of taking 1.75 million cars off the road for an entire year.

GCC’s presentation ended with a brief discussion of environmental product declarations and an acknowledgement that as of 2023, all U.S. DOTs have accepted PLC.

GCC remains committed to achieving carbon neutrality using energy-efficient technologies and innovative alternative fuel mixtures in the production of our sustainable PLC cement. We look forward to continuing to serve our communities with quality, sustainable products, innovative solutions and excellence in customer service.

Anyone with questions about PLC or admixtures can reach out to our technical services team for assistance. Thank you, American Concrete Pavement Association , for inviting us to share about PLC!

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