Example of ASR-related map-cracking in concrete pavement (Photo: L. Sutter)
The new Winter Quarter NC² Moving Advancements into Practice (MAP) Brief titled “Understanding ASR. . .AND How to Mitigate It” is now available. This MAP brief summarizes Alkali-aggregate reaction (AAR)—a potential distress mechanism for Portland cement concrete (PCC) that results from a reaction between alkali hydroxides in the PCC pore solution and reactive aggregates.
• The most common occurrence of AAR is the alkali-silica reaction (ASR) that results from reactions involving specific siliceous aggregates.
• The much less common occurrence of AAR is alkali-carbonate reactivity (ACR), which occurs with very specific types of carbonate aggregates.
Both forms of AAR generally manifest as map cracking over a large area accompanied with expansion-related distresses (e.g., joint closure, spalling, blowups). Methods for prevention or mitigation of ASR start with avoiding the use of reactive aggregates when possible. When reactive aggregates must be used, ASR can be mitigated in most cases by including in the concrete mixture supplementary cementitious materials (SCMs) or lithium compounds, limiting the alkali loading in the concrete, and minimizing exposure of the concrete to moisture. … READ MORE
Click to go to 12-page MAP Brief
For the 12-page MAP Brief Winter 2020 Overview of “Understanding ASR … AND How to Mitigate It”, please click on image of title page above, go to: https://intrans.iastate.edu/app/uploads/2020/12/MAPbriefWinter2020.pdf
Since beginning in May 2010 under the former CP Road Map, MAP Briefs have served as a concise quarterly channel of concrete pavement technology transfer, describing promising research and technologies that can be used now to enhance concrete paving practices. For the ISCP article titled “History of the CP Road Map”, please go to: https://www.concretepavements.org/2020/05/14/history-of-the-cp-road–map/
Click on image to go to Concrete Clip on YouTube
Featured FHWA Concrete Clips: This quarter, CPTech features the Concrete Clips addressing Cement Manufacturing and Aggregates for Concrete Paving Mixtures.
CP Tech RESEARCH DATABASE:
Learn more about . . . rapid construction:
This quarter, CP Tech is featuring an example search on the topic of rapid construction. Below are the first several hits for the example search query “rapid construction” from the Concrete Infrastructure Research Database that covers both in-progress and recently completed concrete pavement and bridge deck research. This quarter, find relevant projects by browsing the list or using the search box by typing in “rapid construction”.
Click to enlarge image. Click link below to go to page.
This database of in-progress and recently completed research related to concrete pavements and bridge decks across the US is partially a product of the former CP Road Map (or Long-Term Plan for Concrete Pavement Research and Technology). It is updated twice a year. Originally developed under the former CP Road Map, research included in the database is identified from the Transportation Research Board (TRB) list of Research in Progress (RiP), newsletters from across the concrete industry, and agency websites. For the Infrastructure Research DATABASE PAGE, please go to: https://cptechcenter.org/concrete-infrastructure-research-database/
NEWS FROM THE ROAD
NEWS FROM THE ROAD highlights recently completed research around the country that helps the concrete pavement community meet the research priorities outlined by the NC² member states. For all of the news articles below, please click on link in the “Read More” prompt or go to: https://mailchi.mp/882b53ce56e0/winter-2020-nc2-news?e=2945805a7f
Click to go to report
Concrete Patching Materials and Techniques and Guidelines for Hot Weather Concreting: Improving the Durability of High Early Strength Cement-Based Patching Materials for Concrete Pavements
This report examines the construction practices associated with long patches of high-early-strength concrete that fail to obtain long-term strength. (Read this report OR view associated slides….)
Click to go to report
Fiber Reinforcement for Latex-Modified Concrete Overlays
This report evaluates whether nonmetallic fibers in latex-modified concrete reduce cracking in bridge deck overlays under suboptimal conditions. (Read this report….)
Click to go to report
Enhancing the Performance of Fiber-Reinforced Concrete in Construction and Repair
This report focuses on improving the crack resistance and flexural properties of Eco-Bridge-Crete, fiber-reinforced self-consolidating concrete, and fiber-reinforced super-workable concrete. (Read this report….)
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Evaluation, Beneficiation, and Implementation of Alternative Concrete Pozzolans for Transportation Infrastructure
This report evaluates fluidized bed combustion fly ash and impure calcined clay as alternatives to coal fly ash, ground granulated blast furnace slag, and other supplementary cementitious materials. (Read this report….)
For this Winter 2020-2021 E-News and all ARCHIVED NCC E-News, please go to: https://cptechcenter.org/nc2-news/
To find out more about the CP Road Map, or to get involved, contact:
Steve Tritsch, HCE Services, Inc.
E-mail: stritsch@iastate.edu | Phone: 515-294-3230
Address: CP Tech Center | 2711 S Loop Drive • Suite 4700 | Ames, IA 50010
The NC² E-News, originally the quarterly newsletter of the former CP Road MAP program, overviews new developments in concrete pavement research and technology from around the country.