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TitleAsphalt Mix Design Procedure
Tags Specification (Technical Standard) Road Surface Construction Aggregate Quality Assurance
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                            Transportation Research Circular E-C124: Practical Approaches to Hot-Mix Asphalt Mix Design and Production Quality Control Testing
2007 Executive Committee Officers
2007 Technical Activities Council
Practical Approaches to Hot-Mix Asphalt Mix Design and Production Quality Control Testing
General Issues in Asphalt Technology Committee
Characteristics of Bituminous Paving Mixtures to Meet Structural Requirements Committee
Contents
Preface
Current Superpave Mix Design Practice: Survey of the User–Producer Regions
A Look at the Bailey Method and Locking Point Concept in Superpave Mixture Design
Analysis of Oklahoma Mix Designs for the National Center for Asphalt Technology Test Track Using the Bailey Method
Using the Superpave Gyratory Compactor to Estimate Rutting Resistance of Hot-Mix Asphalt
Using the Indirect Tension Test to Evaluate Rut Resistance in Developing Hot-Mix Asphalt Mix Designs
National Academy of Sciences
	Transportation Research Board
National Academies identifier
                        
Document Text Contents
Page 1

T R A N S P O R T A T I O N R E S E A R C H

Number E-C124 December 2007

Practical Approaches
to Hot-Mix Asphalt Mix
Design and Production

Quality Control Testing

Page 2

TRANSPORTATION RESEARCH BOARD
2007 EXECUTIVE COMMITTEE OFFICERS

Chair: Linda S. Watson, Executive Director, LYNX–Central Florida Regional Transportation Authority, Orlando
Vice Chair: Debra L. Miller , Secretary, Kansas Department of Transportation, Topeka
Division Chair for NRC Oversight: C. Michael Walton, Ernest H. Cockrell Centennial Chair in Engineering,

University of Texas, Austin
Executive Director: Robert E. Skinner, Jr., Transportation Research Board


TRANSPORTATION RESEARCH BOARD
2007 TECHNICAL ACTIVITIES COUNCIL

Chair: Neil J. Pedersen, State Highway Administrator, Maryland State Highway Administration, Baltimore
Technical Activities Director: Mark R. Norman , Transportation Research Board

Paul H. Bingham, Principal, Global Insight, Inc., Washington, D.C., Freight Systems Group Chair
Shelly R. Brown, Principal, Shelly Brown Associates, Seattle, Washington, Legal Resources Group Chair
James M. Crites, Executive Vice President, Operations, Dallas–Fort Worth International Airport, Texas, Aviation

Group Chair
Leanna Depue, Director, Highway Safety Division, Missouri Department of Transportation, Jefferson City, System

Users Group Chair
Arlene L. Dietz, A&C Dietz, LLC, Salem, Oregon, Marine Group Chair
Robert M. Dorer, Deputy Director, Office of Surface Transportation Programs, Volpe National Transportation

Systems Center, Research and Innovative Technology Administration, Cambridge, Massachusetts, Rail
Group Chair

Robert C. Johns, Director, Center for Transportation Studies, University of Minnesota, Minneapolis, Policy and
Organization Group Chair

Karla H. Karash, Vice President, TranSystems Corporation, Medford, Massachusetts, Public Transportation
Group Chair

Marcy S. Schwartz, Senior Vice President, CH2M Hill, Portland, Oregon, Planning and Environment Group Chair
Leland D. Smithson, AASHTO SICOP Coordinator, Iowa Department of Transportation, Ames, Operations and

Maintenance Group Chair
L. David Suits, Executive Director, North American Geosynthetics Society, Albany, New York, Design and

Construction Group Chair

Page 42

Gierhart 37



TABLE 3 Bailey Principle No. 1


Fine in Control Coarse in Control
Coarse fraction spread apart and floating in the
fine fraction.

Fine aggregate mainly fills voids created by
coarse aggregate.

Little to no particle-on-particle contact of the
coarse aggregate.

There is some degree of particle-on-particle
contact of the coarse aggregate.

Fine fraction carries most of the load. Coarse fraction carries most of the load.
Fine aggregate must have sufficient gradation,
shape, texture, and strength to support the load.

Coarse aggregate must have sufficient gradation,
shape, texture, and strength to support the load.
However, the fine aggregate does play a role in
supporting the coarse aggregate.

6% change in PCS results in approximately 1%
change in VMA or air voids.

4% change in PCS results in approximately 1%
change in VMA or air voids.

Decreasing coarse aggregate volume increases
VMA and voids (providing fine fraction
characteristics remain similar).

Increasing coarse aggregate volume increases
VMA and voids (providing fine fraction
characteristics remain similar).

As the coarse aggregate volume increases above
tolerances, the mix can go in and out of coarse
aggregate interlock, resulting in problems.

As the coarse aggregate volume increases above
tolerances, compactability decreases, and chance
of segregation increases.



retained on the PCS are called interceptors. The interceptors are too large to fit into the voids
created by the pluggers and therefore spread them apart. The ratio of the % interceptors to the %
pluggers is defined as the coarse aggregate (CA) ratio. Principle No. 2 is summarized in Table 4.

Principle No. 3

This principle deals with the coarse part of the fine fraction of the aggregate structure. Because of
the inherent differences between fine and coarse mixes, the fine fraction is defined differently for
each mix type. The evaluation of this portion of the aggregate structure uses the idea of the
secondary control sieve (SCS). The ratio of the fine part of the fine fraction to the total fine fraction
is defined as the fine aggregate (FAc) ratio. Therefore, 1 – FAc ratio is the decimal amount of the
coarse part of the fine fraction. The FAc ratio is the primary factor in the controlling the VMA and
voids of the mixture. Key features of this principle are shown in Table 5.

Principle No. 4

This principle deals with the fine part of the fine fraction of the aggregate structure. Because of
the inherent differences between fine and coarse mixes, the fine fraction is defined differently for
each mix type. The evaluation of this portion of the aggregate structure uses the idea of the
tertiary control sieve (TCS). The ratio of the fine part of the fine part of the fine fraction to the
total fine part of the fine fraction is defined as the FAf ratio. Therefore, the small particles
passing the TCS fit into the voids created by the coarser particles found between the SCS and the
TCS. This principle is described in Table 6.

The results of the analysis of each mix using the principles of the Bailey method follow.

Page 43

38 E-C124: Practical Approaches to Hot-Mix Asphalt Mix Design and Production Quality Control Testing



TABLE 4 Bailey Principle No. 2


Fine in Control Coarse in Control
Half sieve = 1/2 the original PCS. The PCS is
now looked at as the new nominal maximum
particle size (NMPS).

Half sieve = 1/2 the original NMPS.

New PCS = 0.22 times the original PCS. PCS stays as originally defined.
The portion evaluated as the new coarse fraction
is smaller than that of coarse mixes and therefore
less sensitive to changes.

The portion evaluated as the coarse fraction is
larger than that of fine mixes and therefore more
sensitive to changes.

0.35 increase in CA ratio results in approximately
1% increase in VMA or air voids.

0.20 increase in CA ratio results in approximately
1% increase in VMA or air voids.

Too-low CA ratio means too few interceptors and
therefore VMA and voids are lower.

Too-low CA ratio means too few interceptors and
therefore VMA and voids are lower.

By definition of fine mixes, the coarse particles
are floating in the fine particles. Therefore the CA
ratio of fine mixes does not relate to segregation.

Too-low CA ratio means too many coarse
particles and therefore the mix is prone to
segregation.

Too-high CA ratio means too many interceptors
and therefore the mix is tender and difficult to
properly compact.

Too-high CA ratio means too many interceptors
and therefore the mix is tender and difficult to
properly compact.

CA ratio acceptable range is 0.6–1.0 CA ratio acceptable range changes depending on
NMPS.




TABLE 5 Bailey Principle No. 3


Fine in Control Coarse in Control
SCS = 0.22 times the new PCS. SCS = 0.22 times the original PCS.
New PCS = 0.22 times the original PCS. PCS stays as originally defined.
FAc ratio acceptable range is 0.35–0.50 FAc ratio acceptable range is 0.35–0.50
0.05 increase in FAc ratio up to 0.50 results in
approximately 1% decrease in VMA or air voids.

0.05 increase in FAc ratio up to 0.55 results in
approximately 1% decrease in VMA or Air voids.

Once FAc ratio increases beyond 0.50 VMA
begins to increase.

Once FAc ratio increases beyond 0.55 VMA
begins to increase.

As FAc ratio increases toward 0.50,
compactability of fine fraction increases.

As FAc ratio increases toward 0.55,
compactability of fine fraction increases.




TABLE 6 Bailey Principle No. 4


Fine in Control Coarse in Control
TCS = 0.22 times the new SCS. TCS = 0.22 times the original SCS.
New SCS = 0.22 times the new PCS. SCS stays as originally defined.
FAf ratio acceptable range is 0.35–0.50 FAf ratio acceptable range is 0.35–0.50
As the FAf ratio increases up to 0.50, VMA
decreases.

As the FAf ratio increases up to 0.55, VMA
decreases.

Once FAf ratio increases beyond 0.50 VMA
begins to increase.

Once FAf ratio increases beyond 0.55 VMA
begins to increase.

Page 83

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Page 84

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