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Effect of Pavement Thicknesson Superpave Mix
Permeability and Density
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James CrovettiMarquette University
Robert Schmitt University of Wisconsin-Platteville
Jeffrey Russell, Hussain U. Bahia, Kunnawee KanitpongUniversity of Wisconsin-Madison
EFFECT OF PAVEMENT THICKNESS ON SUPERPAVE MIX PERMEABILITY AND DENSITY
WisDOT Highway Research Study 0092-02-14
Jeffrey Russell, Professor Hussain U. Bahia, Associate Professor
Kunnawee Kanitpong, Research Assistant University of Wisconsin Madison
Department of Civil and Environmental Engineering 1415 Engineering Drive, Madison, WI 53706-1490
Robert Schmitt University of Wisconsin- Platteville
Department of Civil & Environmental Engineering University Plaza, Platteville, WI 53818
James Crovetti Marquette University
Department of Civil & Environmental Engineering Haggerty Engineering Hall
Milwaukee, WI 53201
Wisconsin Department of Transportation Division of Transportation Infrastructure Development
Research Coordination Section 4802 Sheboygan Ave., Box 7065, Madison, WI 53707-7910
Disclaimer This research was funded through the Wisconsin Highway Research Program by the Wisconsin Department of Transportation and the Federal Highway Administration under Project # 0092-02-14. The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views of the Wisconsin Department of Transportation or the Federal Highway Administration at the time of publication.
This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification or regulation.
The United States Government does not endorse products or manufacturers. Trade and manufacturers names appear in this report only because they are considered essential to the object of the document.
There are many people who contributed to the completion of this project. Some
of the more important contributors include the members of the Wisconsin Highway
Research Program Flexible Pavement Technical Oversight Committee. Their feedback
and support, especially Erv Dukatz, Judie Ryan, and Tom Brokaw are gratefully
The authors gratefully acknowledge the support of the Payne and Dolan Inc., Ms.
Signe Reichelt, and the Mathy Construction, Dr. Erv Dukatz for their support in
providing information of the field projects selected in this study. Authors would also like
to thank Mr. Jacques Menard from Marquette University, Mr. Anthony Stakson and Mr.
Ahmed Faheem from the University of Wisconsin-Madison for their assistances in
collecting the field data, and Ms. Susan Brunsell for her coordination in the project.
The authors would also like to thank Mr. Greg Waidley for his support in
finishing the final version of this report and for his review of the document.
Technical Report Documentation Page
1. Report No.
2. Government Accession No
3. Recipients Catalog No
4. Title and Subtitle Effect of Pavement Thickness on Superpave Mix Permeability and Density
5. Report Date : April 2005 6. Performing Organization Code 0092-02-14
7. Authors J.S. Russell, Professor, H.U. Bahia, Associate Professor, and K. Kanitpong, Research Assistant
8. Performing Organization Report No.
9. Performing Organization Name and Address University of Wisconsin Madison Department of Civil and Environmental Engineering 1415 Engineering Drive Madison, WI 53706-2507
10. Work Unit No. (TRAIS) 11. Contract or Grant No. WisDOT SPR# 0092-02-14
12. Sponsoring Agency Name and Address Wisconsin Department of Transportation Division of Transportation Infrastructure Development Research Coordination Section 4802 Sheboygan Ave., Box 7065, Madison, WI 53707-7910
13. Type of Report and Period Covered 14. Sponsoring Agency Code
15. Supplementary Notes 16. Abstract: This research study was conducted to determine the influence of maximum aggregate size, lift thickness, and aggregate source on the density and permeability of asphalt mixtures designed according to the Superpave criteria. The guidelines for the selection of pavement layer thickness based on nominal maximum aggregate size and gradation for use in Wisconsin were developed, and the permeability and density criteria for Superpave mixture designs in Wisconsin based on traffic, lift thickness, field drainage and moisture conditions were recommended. In addition, the laboratory and field permeability testing procedures and equipment for design and quality control of Superpave mixtures in Wisconsin were recommended. This project presents the results of 16 mixes used on 9 field projects, including all critical variables affecting the density and permeability of HMA. The in-place density and field permeability were measured by using the nuclear gauge and the NCAT device, respectively. Field cores were taken for measuring permeability in the laboratory by using the ASTM D5084 method; and laboratory compaction was used to prepare and test samples from loose mixtures recovered from the field. The results from field study indicate that that density and permeability of Superpave mixes are based on project-specific variables. Base type, source, gradation, and Ndes level all influence field density and permeability. For fine-graded mixes, the t/NMAS ratio showed an influence on achieving density, particularly below a ratio of 2 for gravel-source mixes and a ratio of 3 for limestone-source mixes. No clear relationship was found between t/NMAS ratios and permeability. For coarse-graded mixes, mixes compacted at smaller t/NMAS ratios for limestone-source were more permeable than higher ratios, but no trend was observed for the gravel-source mix. It was also found that there is a good correlation between the gradation of aggregate and permeability. As the ratio of (%P1/2 - %P3/8) / (%PNo.4-%PNo.8) increases, the permeability decreases, and as the gaps between the coarse aggregates (%P1/2 and %P3/8) and/or the fine aggregates (%P4 and %P8) increase, the permeability increases. This could be the effect of differences in aggregate sizes on the internal void structure, and thus measured permeability, of the compacted material. This trend could be used in mix design by controlling the ratio to limit permeability by either reducing the difference between the coarse sieves, fine sieves, or both. In laboratory study, two compaction procedures, called Method A and Method B were used to produce Superpave Gyratory Compacted (SGC) specimens that have similar thickness, air voids, and aggregate orientation of the field cores. The result indicates that Method B, which is based on using Ndesign gyrations for different sample sizes, can be used to produce samples that give permeability values similar to values measured for field cores. The results indicate a good relationship between field permeability (using the NCAT device) and lab permeability measured on field cores of fine-graded mixes with amount of passing No. 8 sieve (P8) higher than 45%. However, the relationship between field
permeability and lab permeability measured on field cores of coarse-graded mix (P8 lower than 40%) is very poor. It is therefore concluded that the NCAT permeability device could possibly be used in the field for fine-graded mix (with P8 higher than 45%) to measure a permeability index that is related to the true permeability of field cores as measured by the ASTM D5084. However, to measure the field permeability of coarse-graded mix (P8 lower than 40%), an approach to prevent water leakage along the sealant due to rough pavement surface should be established. For coarse graded mixtures, there appears to be no current alternative better than taking field cores and testing them in the laboratory. For estimating permeability during mixture design, a simple method for preparing and testing permeability of SGC specimens and interpolating based on expected field density is introduced. The results represent a good estimate of the expected in-place field permeability. The recommendations from this study include no changes in the selection of pavement thickness and t/NMAS ratios in the specifications. However, this recommendation does not ensure achieving density nor limit permeability. It is also recommended that for the permeability and density criteria for Superpave mix designs, the target permeability and density values should be developed from in-service pavements with recorded performance histories. For further study, the warranty projects with proven record of performance can be used to define target density and permeability criteria for HMA pavement in Wisconsin. 17. Key Words Density, Permeability, HMA, Superpave, Lift Thickness, NMAS, t/NMAS, Gradation
18. Distribution Statement
No restriction. This document is available to the public through the National Technical Information Service 5285 Port Royal Road Springfield VA 22161
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