NC² Spring 2020 Quarterly E-News: NC² MAP Brief & “News From the Road” & More

NATIONAL CONCRETE CONSORTIUM (NC²) SPRING 2020 Quarterly E-News:

Featured FHWA Concrete Clips—

This quarter, CP Tech features the Maturity and Strength Gain and Admixtures Concrete Clips. Concrete Clips is a series of short technical videos developed by FHWA. Each quarter’s NC² E-News will feature 2 of their now 13 Concrete Clips available. To view the clips, please click on image to left, or go to: www.youtube.com/playlist?list=PL5_sm9g9d4T1ND5YlNt0OuL6g2T_NbGdR 

Recent NC² States’ Q&A Listserv Activity—

NC2 State Survey—Member states of the National Concrete Consortium (NC2) have the ability to poll other member states regarding specifications, materials, construction, research, or other issues related to concrete paving. For this winter’s updated list of NC² Listserv questions and answers, please go to: cptechcenter.org/nc2-listserv-questions/

Learn more about . . . bridge deck cracking: This quarter, CP Tech Center is drawing attention to resources covering bridge deck construction and related issues in the Concrete Infrastructure Research Database—an in-progress and recently completed research that allows easy search of curated research related to concrete pavements and bridge decks across the US from the previous 5 years. The list displayed to the right shows the first several articles from the search results. Please click on the image for all of the updated articles pertaining to this quarter’s subject. For the database, please go to: www.cptechcenter.org/concrete-infrastructure-research-database/

The CP Tech Center is also encouraging engineers and other professionals to review recent questions, included one added by the WV DOT, in the NC² States’ Q&A Listserv, which allows member states of the TTCC Pooled Fund to poll other member states regarding specifications, materials, construction, research, or other concrete paving issues. For the NC² States’ Q&A Listserv, please go to: www.cptechcenter.org/nc2-states-listserv-questions/

To view the web page, and enter “bridge deck” in search field, please go to: www.cptechcenter.org/nc2-resource-library/

Also this quarter…
WEST VIRGINIA has added to the NC² States’ Q&A Listserv a new specifications-related question along with responses from nineteen state DOTs:
“What certifications/qualifications (i.e., CCRL, AASHTO, ACI, in-house program, etc.) do you require for laboratories who test contractor QC cylinders, or contractor cylinders that may be used for acceptance, on DOT projects in your state?”
GEORGIA has added a new design-related question about new concrete pavement construction, along with responses from seventeen state DOTs:
“What design method do you use? What slab thickness intervals do you use, e.g., 8”-10”-12”; 8“-9”-10”; 8”-8.5”-9”; 8”-8.25”-8.5”; etc. Why? If you use less than 1” increments or have used them in the past, what, if any, challenges were faced during construction?”

All answers to these questions (and others) can be found at the NC² States’ Q&A Listserv. The NC² States’ Q&A Listserv allows member states of the TTCC Pooled Fund to poll other member states regarding specifications, materials, construction, research, or other concrete paving issues. For the LISTSERV, please go to: https://cptechcenter.org/nc2-states-listserv-questions/

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New NC² MAP Brief Available—Moving Advancements into Practice (MAP) Brief — describes promising research and technologies that can be used now to enhance concrete paving practices. The SPRING 2020 MAP Brief, “Extended-Life Concrete Bridge Decks Utilizing Internal Curing to Reduce Cracking–Results from Ohio DOT Field Trial”, describes eliminating or reducing cracking in bridge decks, which has been a priority goal for DOTs for a number of years. Early-age deck cracking results in making the bridge deck as well as the supporting substructure elements particularly susceptible to moisture and chloride ingress—the cracks provide a direct pathway for the intrusion of water and chlorides. In the worst case, these early-age cracks could lead to reduced deck and substructure service life. Many agencies began taking mitigating measures in the 1980s by using corrosion-resistance coatings for steel reinforcement. But cracks still leave the concrete itself with an increased susceptibility to premature deterioration. The 8-page brief includes a brief introduction, which details common causes and contributing factors. The publication also includes:
• What is Internal Curing?
• Mixture Considerations
• Ohio Field Trials
• Mixture Designs
• Construction Placement (and Structural Testing)
• Performance Monitoring
• Service Life Prediction
• LCCA Analysis
• Ohio’s Future Plans Regarding Using lightweight fine aggregates (LWFA) for Internal Curing
• Specialized mixture designs to mitigate cracking

For the 8-page SPRING 2020 MAP Brief, please click on image to the above left, or go to: https://intrans.iastate.edu/app/uploads/2020/03/MAPbriefSpring2020.pdf

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NEWS FROM THE ROAD highlights research around the country that is helping the concrete pavement community meet the research objectives outlined in the CP Road Map. The research projects and the summaries described herein are the product of the researcher and sponsor(s). For all of the news articles below, please click on link headline in each title below, the “Read More” prompt, on the image to the left, or go to: https://mailchi.mp/51ec75317cdf/spring-2020-nc2-news?e=2945805a7f

Reducing Cracks in Concrete Bridge Decks Using Shrinkage Reducing Admixture: Restrained shrinkage cracking of concrete bridge decks creates a significant durability problem. Major admixture suppliers in the United States have introduced a new category of chemical admixtures called shrinkage reducing admixtures (SRAs). SRAs work by reducing the surface tension of pore water and thereby decreasing the capillary stress and shrinkage induced by drying. … The purpose of this study was to investigate the effectiveness of SRAs in reducing drying shrinkage in Virginia Department of Transportation (VDOT) concrete mixtures and thus reducing cracks in bridge decks. Please Read More

Bridge Decks: Mitigation of Cracking and Increased Durability: The application of pre-soaked lightweight aggregates (LWA) as an internal curing agent in concrete to reduce the cracking due to drying shrinkage is thoroughly studied in this report. It is determined that although LWA can significantly reduce autogenous shrinkage, its effect on drying shrinkage is minimal and, in some cases, it can even increase the drying shrinkage. Moreover, the combined effects of LWA and expansive cement (Type K), as well as LWA and shrinkage-reducing admixtures (SRAs), on drying shrinkage is also studied. It is shown that the addition of Type K cement or SRA to mixtures containing LWA can significantly reduce drying shrinkage and make the mixture more volumetrically stable. Read More

Performance-Related Specifications for Pavement Preservation Treatments: This report (1) presents guidelines for preparing performance-related specifications (PRS) for pavement preservation treatments and, if desired, determining pay adjustment factors and (2) illustrates the applicability of these guidelines for selected preservation treatments for flexible and rigid pavements. The guidelines follow a systematic process that considers acceptance quality characteristics and performance measures for preservation treatments. The information contained in the report will be of immediate interest to state materials and maintenance engineers and others involved with the specification and quality aspects of pavement preservation treatments. Read More

High-Early-Strength High-Performance Concrete for Rapid Pavement Repair: In the construction industry, High-Early-Age-Strength (HES) concrete has traditionally been regarded as a concrete that achieves loading strength in mere days rather than weeks. However, in the last 10 to 15 years, this time has reduced down to just hours. Required minimum compressive strength is determined case by case. For:
• Structures and dwellings, the minimum allowed by the International Building Code is 2,500 psi.
• Road and bridge construction, the minimum is typically 3,000 psi.
• Airport construction, it is typically 4,000 psi.
Due to the accelerated strength gain of HES provided by chemical admixtures, minimum opening strengths are often reduced since the concrete is expected to continue gaining strength after traffic load is introduced. This investigation targets high-early-age-strength concrete for the purposes of road and bridge deck repairs … Read More

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To find out more about the CP Road Map, or to get involved, contact:
Steve Tritsch, HCE Services, Inc.
E-mail: dharrington@hceservices.com  |  Phone: 515-294-3230
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