How to entrain air voids for pavements that last
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February has been cold—freezing cold. Such weather can be hard on people, but freeze-thaw cycles also damage concrete pavements, especially in wet climates.
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Entrained air void systems are known to improve concrete freeze-thaw durability. Nevertheless, requirements and practices have not taken adequate account of innovations in admixtures, supplementary cementitious materials (SCMs), and ice control. Also, test methods designed to enable quality control actions in the field have been found inadequate for current concrete mixtures.
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Through a recent report published by the National Cooperative Highway Research Program (NCHRP), researchers from the CP Tech Center and University of Missouri (Kansas City) aim to improve concrete paving practice via minimum fresh and hardened air void system requirements and better test procedures.
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Better measurements a key to better foundations
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A recent CP Tech Center report on pavement foundations summarizes a series of field studies funded through an FHWA Transportation Pooled Fund led by Iowa in partnership with California, Michigan, Pennsylvania, and Wisconsin.
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Mechanistic pavement design assumes uniformity of support across a pavement's foundation system. However, this project's site investigations revealed substantial spatial nonuniformity in newly constructed pavement foundations across a wide range of geomaterials. The work demonstrates that if the subgrade is nonuniform, the overlying aggregate base will also be nonuniform, and that poor support cannot be rehabilitated by increasing pavement thickness.
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The study also found virtually no verification of the engineering parameters assumed by pavement foundations' mechanistic design. This summary report reviews new performance-based earthwork specifications and provides a performance-based framework and workflow for field process control and mechanistic pavement foundation testing to link design target values with as-constructed QA.
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Join the CP Tech Center's new webinar series
on cost-effective, cutting-edge technologies
Join industry, national, state, and local agency/consulting firms
to learn about new technologies and research innovations holding promise of
both enhancing the performance and lowering the cost of concrete pavements
through this new webinar series launched in collaboration with the
American Concrete Pavement Association (ACPA)
Real Time Curing Control/Construction Productivity Research
Friday, March 5th at 11 am (CST)
This Cutting-Edge Concrete Technology webinar
provides one Professional Development Hour (PDH)
and is available for signup here.
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Join upcoming CP Tech Center
Concrete Pavement Technology Tuesday
webinars
on
Tuesdays at 12 pm (CST)
- March 9: Advancements in our knowledge and action to control alkali-silica reaction (ASR) in concrete pavements
- April 6: Understanding the value of competition
- May 11: Best practices for recycled concrete aggregate (RCA)
All webinars offer Professional Development Hours (PDHs)
and are available for signup here.
(Previous webinar recordings, slide handouts, and speakers' Q&A responses are available here.)
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CP Tech Center continues "traveling" virtually
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As virtual meetings, seminars, and conferences have become an accepted norm, the impact of CP Tech Center webinars and other resources has multiplied not only nationwide but worldwide—in part because nearly all CP Tech Center events the past year have been recorded and posted to the CP Tech Center website, where they are available for free whenever needed for reference or training.
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For example, need to know more about pavement preservation? In the CP Tech Center's January 12ᵗʰ Concrete Pavement Technology Tuesday webinar, John Roberts, PE (International Grooving and Grinding Association), and Joe Echelle, PE, MBA (Oklahoma Turnpike Authority), presented "Dowel Bar Retrofit and Diamond Grinding Best Practices" to 499 participants.
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Or interested in learning how fiber reinforcement makes a difference? For the CP Tech Center's Technology Tuesday webinar held on February 9ᵗʰ, Dr. Jeff Roesler, PE (University of Illinois at Urbana-Champaign), gave a presentation to 452 participants on "Understanding the Application/Benefit of Fiber Reinforcement in Concrete."
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Even attendance at the CP Tech Center's historically local Iowa Concrete Lunch & Learn has broadened, with 276 joining a January 22ⁿᵈ talk on "Subgrades & Subbases" by Melissa Serio, PE, about the Iowa DOT's work to improve pavement performance via modulus verification roller mapping of foundation layers.
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Similarly, for the February 5ᵗʰ Iowa Concrete Lunch & Learn, 320 participants joined a presentation on "Troubleshooting Concrete Projects" by Jerod Gross, PE, LEED AP, CP Tech Center Technology Transfer Engineer and Snyder & Associates’ Senior Engineer.
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While COVID has opened access to CP Tech Center events and resources more broadly than ever before, CP Tech Center staff remain interested and involved in state and local—and not merely national or global—concrete pavement concerns. As a result, CP Tech Center Director Peter Taylor and Associate Director Gordon Smith tag-teamed in a presentation about performance-engineered mixtures (PEM) to the Utah Ready-Mixed Concrete Association on January 27ᵗʰ, and Peter Taylor shared CP Tech Center activities and resources with the Michigan as well as Pennsylvania ACPA chapters on February 17ᵗʰ.
What concrete paving questions do you—or your organization—have? Contact the CP Tech Center with your questions—and/or webinar topics—you want addressed.
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Join
Iowa Concrete Lunch & Learn
webinars
on
Fridays at 12 pm (CST)
- March 5: Construction Inspection: A Just-in-Time Inspection Refresher
All Iowa Concrete Lunch & Learn webinars offer Professional Development Hours (PDHs).
Upon registration via emailing Melisse Leopold your name, email address, organization, and the name of the webinar you wish to attend, you will be emailed an Outlook/Teams invitation to your chosen webinar(s).
(Previous Iowa Concrete Lunch & Learn webinar recordings and slide handouts are available here.)
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Ernie Peterson has been Vice President for Sales, Midwest Division, for Ash Grove Cement Company since 2012 and has worked for the company a total of 24 years. With Ash Grove's addition in 2019 of operations in Florida, the US Great Lakes, and Canada, the company is one of the largest cement producers in North America with 12 cement plants, 42 cement terminals, and 2,500 employees.
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Ernie Peterson serves on the CP Tech Center's Executive Board of Directors as one of the cement industry's at-large representatives. Peterson is also a member of the American Concrete Pavement Association (ACPA) Board of Directors, where he is currently serving on the association's chief executive search and transition team charged with identifying ACPA's next CEO. (ACPA's current president and CEO, Jerry Voigt, is stepping down from executive leadership after 33 years of working for the organization to a less time-intensive—though still strategic—support role.)
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Paving Association Execs
Please forward this newsletter to your members as appropriate.
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