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CP Road Map E-News


January 2020

Moving Advancements into Practice (MAP) Brief

Moving Advancements into Practice (MAP) Briefs describe promising research and technologies that can be used now to enhance concrete paving practices.

The January 2020 MAP Brief, “Development and Deployment of the Next Generation Concrete Surface,” describes the Next Generation Concrete Surface (NGCS), the latest innovation in concrete texture.

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.
Check out this winter's updated list of NC² Listserv questions and answers.

News from the Road

"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).

Implementation of a Testing Protocol for Approving Alternative Supplementary Cementitious Materials (SCMs): Natural Minerals and Reclaimed and Remediated Fly Ashes

Supplementary cementitious materials (SCMs) provide many benefits to concrete mixtures in terms of cost, strength, and durability. Class F fly ash is the most widely used SCM in Texas, but its availability is dwindling while demand is increasing. Given the importance of Class F fly ash as a means to improve concrete durability, it is important to find alternative materials that can maintain the high quality and durability of concrete required in Texas.
TxDOT Project 0-6717: Investigation of Alternative Supplementary Cementing Materials (SCMs), completed in August 2014, identified sources of Class F fly ash alternatives that can be used in Texas concrete and developed best practices for testing these materials. Lower cost sources of materials have been identified since the completion of that project and may present better opportunities for Class F fly ash replacement than those initially tested. These materials include natural mineral byproducts of other industries, reclaimed fly ashes, and remediated fly ashes. The experimental protocols developed in Project 0-6717 were performed on these new sources of materials to determine their suitability for use in Texas concrete. The materials were chemically and physically characterized, and their performance in cement paste, mortar, and concrete mixtures was tested. It was determined that some of the natural minerals were inert; thus, they are not recommended for use in concrete. Natural pumicite performed well as an SCM, including a pumicite that is quarry overburden and could be procured at a relatively low cost. This overburden pumice, however, did not perform as well as expected in testing for sulfate resistance and merits further investigation. It is possible that the overburden pumicite would perform better if used at a higher replacement level of cement. The reclaimed and remediated fly ashes performed very well, proving their ability to be used as substitutes for “production” Class F fly ash based on the criteria established in this project. In the cases where reduced performance was seen in fly ashes, the problems should be easily managed through the addition of chemical admixtures.

This report was written by Saif Al-Shmaisani, Ryan Kalina, Michael Rung, Raissa Ferron, and Maria Juenger. Click here to access the full document. This project was sponsored by Texas Department of Transportation Research and Technology Implementation Office in cooperation with FHWA. The performing organization was the Texas Department of Transportation Research and Technology Implementation Office. This project is contributing to objectives identified in CP Road Map Track 1: Material and Mixes for Concrete Pavements.

Construction of Crack-Free Bridge Decks (April 2017)

The goal of the study described in this final report “Construction of Crack-Free Bridge Decks” for Transportation Pooled-Fund Program Project No. TPF-5(174) was to implement the most cost-effective techniques for improving bridge deck life through the reduction of cracking. Work was performed both in the laboratory and in the field, resulting in the construction of 17 bridge decks in Kansas that were let under Low-Cracking High-Performance Concrete (LC-HPC) specifications. The report documents the performance of the decks based on crack surveys performed on the LC-HPC decks and matching control bridge decks.
The specifications for LC-HPC bridge decks, which cover aggregates, concrete, and construction procedures, as well as procedures for performing crack surveys, are summarized. The first 13 LC-HPC bridge decks are compared to control decks in terms of crack density as a function of time. Survey results are also presented for three LC-HPC decks without control decks and one deck let under LC-HPC specifications on which the specifications were not enforced. The widths of measured cracks ranged from 0.006 in. to 0.025 in., (0.15 mm to 0.64 mm). The LC-HPC bridge decks exhibit less cracking than the matching control decks in the vast majority of cases. Only bridge decks LC-HPC-2 and LC-HPC-3 have higher overall crack densities than their control decks, the two best performing control decks in the program, and the differences are small. The majority of the cracks are transverse and run parallel to the top layer of the deck reinforcement. Relatively short cracks are present near the abutments and propagate perpendicular to the abutments (longitudinally). The study demonstrates the positive effects of reduced cementitious material and cement paste contents, improved early-age and long-term curing, concrete temperature control, limitations on or de-emphasis of maximum concrete compressive strength, limitations on maximum slump, and minimizing finishing operations on minimizing cracking in bridge decks.

This report was written by David Darwin, Ph.D., P.E., Rouzbeh Khajehdehi, Abdallah Alhmood, Muzai Feng, James Lafikes,  Eman Ibrahim, and Matthew O’Reilly. Click here to access the full document. This project was sponsored by Transportation Pooled-Fund Program Project No. TPF-5(174) with the participating states of Colorado, Idaho, Indiana, Kansas, Michigan, Minnesota, Mississippi, North Dakota, New Hampshire, New York, Ohio, Oklahoma, Texas, and Wisconsin. The University of Kansas was the performing  organization. This project is contributing to objectives identified in CP Road Map Track 8: Concrete Pavement Construction, Reconstruction, and Overlays.

Proposed Enhancements to Pavement ME Design: Improved Consideration of the Influence of Subgrade and Unbound Layers on Pavement Performance (2019)

The American Association of Transportation Officials’ (AASHTO) pavement mechanistic-empirical (ME) design software, AASHTOWare Pavement ME Design, and the AASHTO Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) provide a methodology for the analysis and performance prediction of pavements and overlays. The performance of flexible and rigid pavements is known to be closely related to properties of the base, subbase, and/or subgrade.
However, some recent research studies indicated that the performance predicted by this methodology shows a low sensitivity to the properties of underlying layers and does not always reflect the extent of the anticipated effect, so the procedures contained in the Pavement ME Design need to be evaluated.
In addition, proper enhancements should be developed to appropriately account for the influence of subgrade and unbound layers on the performance of flexible and rigid pavements. These enhancements will be incorporated into the Pavement ME Design procedures, which improve the analysis and design of flexible and rigid pavements. This research project proposes and develops enhancements to the Pavement ME Design procedures for both flexible and rigid pavements, which will better reflect the influence of subgrade and unbound layers (properties and thicknesses) on the pavement performance. These enhancements include modifications of the models contained in Pavement ME Design and/or the development of new models.

This work was sponsored by the AASHTO, in cooperation with the Federal Highway Administration, and was conducted in the National Cooperative Highway Research Program (NCHRP), which is administered by the Transportation Research Board (TRB) of the National Academies of Sciences, Engineering, and Medicine.

This report was written Robert L. Lytton, Xue Luo, Sajib Saha, Yu Chen, Yong Deng, Fan Gu, Meng Ling, Texas A&M Transportation Institute; National Cooperative Highway Research Program; Transportation Research Board; National Academies of Sciences, Engineering, and Medicine. Click here to access the full document. This project is contributing to objectives identified in CP Road Map Track 1:  Performance-Based Design Guide for New and Rehabilitated Concrete Pavements.

Impact of Joint Spacing on Bonded Concrete Overlay of Existing Asphalt Pavement in the AASHTOWare Pavement ME Design Software

This paper describes the impact of joint spacing or panel size on the performance and relative cost of short jointed bonded concrete overlay of asphalt (SJPCP) pavement using the AASHTO Pavement ME Design procedure. Joint spacing, or panel dimension, is a critical design issue that greatly affects both performance and cost of the SJPCP as well as conventional jointed plain concrete pavement (JPCP) overlays. In fact, pavement performance is more dictated by the panel size than thickness. Three factors that greatly affect the performance of SJPCP include (1) traffic (truck) volume, (2) wheel load placement and panel size, and (3) layer bonding of portland cement concrete (PCC) to asphalt concrete (AC). This paper focuses on the second point, wheel placement or panel size, which defines the location of critical stresses, location of fatigue damage along the transverse joint, and initiation of corner, longitudinal, and transverse fatigue cracking.
Portions of the bonded concrete overlay of asphalt-mechanistic empirical (BCOA-ME) procedure developed by the University of Pittsburgh were implemented into the AASHTOWare Pavement ME Design (Pavement ME) software (version 2.3, July 2016) for joint spacing ranging from 1.5 to 2.4 m (5 ft to 8 ft) and appropriate thicknesses. This range of joint spacing was implemented based on the impact of joint spacing on BCOA fatigue cracking as described in this paper.

This research project was completed by Biplab B. Bhattacharya, Transportation Engineer, California Department of Transportation; Alex Gotlif, Senior Engineer, Applied Research Associates, Inc., 100 Trade Center Dr., Suite 200, Champaign, IL 61820; Michael I. Darter, Principal Engineer, Applied Research Associates, Inc., 100 Trade Center Dr., Suite 200, Champaign, IL 61820;  and, Lev Khazanovich, Anthony Gill Chair Professor, Department of Civil and Environmental Engineering, University of Pittsburgh, 3700 O’Hara St., 703 Benedum Hall, Pittsburgh, PA 15261. Click here to access the full document. This project is contributing to objectives identified in CP Road Map Track 2:  Performance-Based Design Guide for New and Rehabilitated Concrete Pavements.

Impact of Water/ Cementitious-Based Concrete Mix Design Specification Changes on Concrete Pavement Quality (July 2018)

This research investigated the impact of Minnesota DOT implementing a w/cm-based specification for concrete pavements. Pavement sections constructed before and after the specification implementation were examined to assess permeability, compressive strength, and air-void system parameters. Pavement management system data was examined to identify changes in ride quality associated with the specification change.
The results show the change to a w/cm-based specification resulted in concrete with lower permeability, higher strength, and increased air content. The ride quality for those pavements appears to be better and the rate of degradation of ride quality appears to be slower.

This report was written by Lawrence Sutter, Gerard Moulzolf, and Maria Masten. Click here to access the full document. This research was sponsored by Minnesota DOT, Research Services and Library and performed by American Engineering Testing. This project is contributing to objectives identified in CP Road Map Track 1:Materials & Mixes for Concrete Pavements.

Relationship Between Erodibility and Properties of Soils (2019)

The goal of this project is to develop reliable and simple equations quantifying the erodibility of soils based on soil properties. The reliability must take into account the accuracy required for erosion-related projects while the simplicity must consider the economic aspects of erosion-related projects. Different soils exhibit different erodibility (sand, clay); therefore, erodibility is tied to soil properties. However, many researchers have attempted to develop such equations without much success.
One problem is that erodibility is not a single number but a relationship between the erosion rate and the water velocity or the hydraulic shear stress. This erosion function is a curve and it is difficult to correlate a curve to soil properties. Another problem that needs to be solved is associated with the availability of several erosion testing devices.
In the laboratory, they include many erosion tests such as the pinhole test, the hole erosion test, the jet erosion test, the rotating cylinder test, the erosion function apparatus test. In the field, they include the jet erosion test, the NC State in situ scour evaluation probe test, the TAMU borehole erosion test and pocket erodometer test, etc. All these tests measure the soil erodibility but give different results. It is important to give the engineers options so that she or he can choose one test or another. Therefore, it would be helpful if all these tests could give the same answer. Indeed, the soil does not know the difference between erosion tests, and the erosion function is a fundamental property of the soil.

This report was written by Dr. Jean-Louis Briaud, P.E., Distinguished Professor of Civil Engineering, Texas A&M University, Project Director and Principal Investigator; Iman Shafii, Research Assistant and Ph.D. Candidate, Texas A&M University; Dr. Zenon Medina-Cetina, Associate Professor of Civil Engineering, Texas A&M University; and, Dr. Hamn-Ching Chen, Joint Professor of Civil Engineering and Ocean Engineering, Texas A&M University. Click here to access the full document. The research was performed under NCHRP Project 24–43 by the Texas A&M University Transportation Institute (TTI). This project is contributing to objectives identified in CP Road Map Track 8: Construction, Reconstruction & Overlays.

Effect of Fiber Characteristics on Fresh Properties of Fiber-Reinforced Concrete with Adapted Rheology

The influence of fiber type and volume on fresh properties of fiber-reinforced self-consolidating concrete (FR-SCC) and fiber-reinforced super-workable concrete (FR-SWC) was investigated. These mixtures were developed for infrastructure construction and repair, respectively, and the fibers were incorporated to reduce cracking and enhance service life of concrete structures.
The fibrous mixtures were proportioned with a Type-G expansive agent (EA) to reduce shrinkage and mitigate the risk of cracking. The selected fibers included a propylene synthetic fiber, five different steel fibers, and a hybrid fiber containing steel and polypropylene multifilament fibers. The fiber volume was fixed at 0.5% for the FR-SCC mixtures and varied between 0.5% and 0.75% for the FR-SWC. The investigated FR-SCC and FR-SWC mixtures had initial slump flow of 660–700 mm and 505–570 mm, respectively, and exhibited excellent passing ability and adequate stability. The investigated FR-SCC and FR-SWC mixtures with passing ability index greater than or equal to 12 and 11, respectively, evaluated using the modified J-Ring test exhibited good flowability without blockage and segregation. The passing ability index was inversely proportional to plastic viscosity for mixtures of a given coarse aggregate content and maximum nominal size of aggregate. Good relationships between slump flow and yield stress and T50 and plastic.

This report was written by Ahmed T. Abdelrazik and Kamal H. Khayat, Missouri University of Science and Technology. Click here to access the full document. This project is contributing to objectives identified in CP Road Map Track 8: Construction, Reconstruction & Overlays.

Paving Association Execs

Please forward this newsletter to your members as appropriate.
Copyright © *2020* *National Concrete Pavement Technology Center*, All rights reserved.

The CP Road Map E-News is the newsletter of the Long-Term Plan for Concrete Pavement Research and Technology (CP Road Map), a national research plan developed and jointly implemented by the concrete pavement stakeholder community. To find out more about the CP Road Map, or to get involved, contact Dale Harrington (515-290-4014).

CP Tech Center / 2711 S Loop Drive / Suite 4700 / Ames, IA 50010

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