Simple changes can bring more sustainable and greener solutions when collaboration occurs between the cement producer and the ready mixed concrete (RMC) producer! By exceeding expectations, proven success, and proven performance, designers and agencies are confident in the value of and excited about using an RMC operation—make the switch from ordinary Portland cement (OPC) to Portland limestone cement (PLC) for all concrete uses.
Creating a Greener Concrete:
PLC is a hydraulic interground Portland cement that contains up to 15% limestone and delivers the same performance as OPC. With about 260 million cubic yards of RMC utilized in the U.S. each year, PLC is an important factor to consider when striving to become a part of the solution to lower CO2 emissions. As concrete is the second most consumed product next to water, and the most widely used building product, the environmental spotlight is often on concrete. Supplemental cementitious materials (SCMs) are already found in many concrete mixes, so the switch from OPC to PLC is the next major step for a concrete producer to lower concrete’s footprint.
Substantial environmental impact savings can be achieved when implementing solutions such as “EcoCemPLC™” from Lehigh Cement. Because at least 75% of OPC goes through an RMC producer, a move to PLC provides a great opportunity for producers to make a significant positive impact on the environment. The cement producer and the RMC producer can work together to bring PLC into everyday use—demonstrating how the industry is responding to the need for greener concrete.
Toby Knott, Vice-President Sales and Marketing Operations-Lehigh Cement Company Midwest said, “We’ve experienced firsthand the importance of working closely with the RMC producers, so owners understand the benefits of using EcoCemPLC can have on their project. We want to continually push for a more sustainably built environment.”
PLC is not new, but is a tried and tested product:
PLC has been in North America for more than a decade and in Europe for as many as three decades. It is through collaboration between the cement producer and RMC producer that PLC is now becoming widely accepted.
PLC Arrives in Indiana:
The use of PLC by the state departments of transportation is increasing. Currently, more than 32 states have accepted PLC in their standard specifications and several more will finalize new specifications in 2021:
September 2020:
Indiana—Inaugural application of PLC on a highway pavement but Indiana Department of Transportation (INDOT) and hired contractor Reith-Riley:
• Project improvement of 15 miles of I-65 in Columbus, Indiana
• NRMCA Producer member Irving Materials, Inc.’s (imi) concrete mixtures with Lehigh Cement’s EcoCemPLC™ in a fast-setting non-removable flowable fill for the base (subgrade) and in the concrete pavement patch mix
• Trial mixes were made of both
• 5 trial mixes were made at 4 yards each for the EcoCemPLC flowable fill
-Best-performing flowable fill mix used 200 pounds of EcoCemPLC in addition to other SCMs
• 2 trial mixes were batched of the EcoCemPLC patching mix (As required by INDOT specifications)
-1 short patches
-2 long patches
• Excellent trial batch test results
• Repairs proceeded
Chad Hayes, Vice-President-Irving Materials, Inc. (imi), Indiana South Region said, “During the process we worked closely with the technical services team of Lehigh Cement [part of Lehigh Hanson, Inc.] as we determined the best trial mixes. Together we formulated the mixes using EcoCemPLC as a pound-for-pound replacement and we were pleased with the results. This is all part of our focused effort at imi to develop lower carbon mixtures for our customers and EcoCemPLC has helped us to meet that goal. As part of that commitment, imi is now using EcoCemPLC in large concrete projects at the new Lehigh Mitchell Plant project.”
Pavement Repair Procedures:
The repair process:
• Compacted dense graded stone place
• Geotextile fabric laid
• EcoCemPLC flowable fill placed approximately 6-8 inches deep in the areas to be repaired
• Another layer of geotextile fabric laid
• Waited 2-4 hours
• Approximately 11 to 12 inches of the EcoCemPLC concrete patch mixture placed
• Concrete roller and hand screed
• Concrete finished by troweling both by hand and bull float
• Finishers learned that using EcoCemPLC made a creamier mix, which was easier to trowel
Proven Performance:
The quality control team for imi RMC producer found that based on Lehigh’s test data, they could use PLC as a pound-for-pound replacement for its previously proven INDOT patch mixes. This particular project specified higher performance requirements for the patching concrete. Typically, the three-day requirement is 550 psi flexural strength. In this case, the project required a three-day strength of 625 psi and open to traffic strength of 425 psi. To achieve this, imi was able to use a typical patching mix design, although a Type IL was used instead of the regular Type I/II. There were not any changes in admixture efficiencies and very few adjustments were made throughout the duration of the project.
For the concrete patching, imi used non-destructive maturity testing rather than flexural strength testing. Using maturity testing, imi was able to achieve the 425-psi strength requirement in 12-15 hours, depending on the ambient conditions. The concrete averaged 730 psi on three-day breaks.
“It worked really well for us. We were pleased with the performance and results we had with both our flowable fill and patching concrete mixes when using EcoCemPLC,” said Nick Mosier, imi.
Exceeding Expectations:
The performance outcome was outstanding, without requiring concrete mix design modifications.
Use of EcoCemPLC on I-65 provided:
• Excellent concrete workability and strength gain
• No negative plastic concrete results
• Big advantage: Flowable fill mixture achieved set in 2 to 4 hours—earlier than the required 8-hour specification
• Entire project placed 68 cubic yards of the flowable fill mixture
• Used approximately 200 pounds per cubic yard of EcoCemPLC
• Used 284 cubic yards for the concrete patch mixture
• Resulted in more than 100 tons of the EcoCemPLC consumed in this public infrastructure project
• Project was expected to be completed over 5 to 6 Saturdays, but instead was finished in 3 Saturdays!
Sam Allison, Reith-Riley said, “We had excellent results and were able to open the interstate to live traffic by mid-afternoon on Sunday. This was well ahead of our six a.m. Monday deadline.”
Delivering Sustainability:
While the use of EcoCemPLC is important due to its excellent performance and ease of use, it also delivers significant sustainability advantages:
• Decreases CO2 emissions by nearly 10% compared to OPC Type I or Type I/II by utilizing up to 15% micro-sized limestone in the cement
• More earth-friendly product
• Still delivers the consistency, versatility and performance expected in concrete
• End result is that I-65 will have the same level of strength and durability as highways manufactured with OPC, but with a smaller carbon footprint
For information on “Carbon Footprint Reduction with PLC”; “Up to 10% Carbon Footprint Reduction”; CO2 Calculator; Resources such as case studies, videos, PLC availability, and more information on PLC and how this durable, resilient option can reduce the carbon footprint by up to 10%, please go to: www.greenercement.com
Article was written by By Michael Collins, Technical Services Manager-Midwest Region, Lehigh Hanson: He has more than 30 years of experience in the areas of quality control, testing and technical services in the cement, concrete and concrete products industries.
For the “Concrete InFocus Online News” ARTICLE titled “The Journey to a Greener Solution Begins When Cement and RMC Producers Collaborate”, please go to: www.concreteinfocus-digital.com/nrcq/0221_summer_2021/MobilePagedArticle.action?articleId=1694209&app=false&cmsId=3921351#articleId1694209
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