Details:

Creators:
Wu, Zhong ; King, Bill
Wu, Zhong ; King, Bill Less -
Corporate Creators:
Louisiana Transportation Research Center
Corporate Contributors:
Louisiana. Dept. of Transportation and Development ; United States. Federal Highway Administration
Louisiana. Dept. of Transportation and Development ; United States. Federal Highway Administration Less -
Subject/TRT Terms:
[+]
Aggregate Aggregate Mixtures Aggregates Fearing Course Mixture Friction Course Friction Resistance Friction Tests Macro-texture Materials Selection Micro-texture Mix Design Physical Properties Polishing Polishing (Aggregates) Rolling Contact Rolling Friction Rolling Resistance Surface Course (Pavements) Texture
Publication/ Report Number:
FHWA/LA.11/485
Resource Type:
Tech Report
Geographical Coverage:
Louisiana
Edition:
Final report; July 2009-June 2011.
Corporate Publisher:
Louisiana Transportation Research Center
Abstract:
The main objective of this study was to develop a Louisiana pavement surface friction guideline that considers polished stone value (PSV) and mixture

type alike in terms of both micro- and macro- surface textures. The polishing and texture properties of aggregates were characterized using the British

Pendulum, Micro-Deval and Aggregate Imaging System (AIMS). Asphalt mixture slabs were fabricated with different combinations of two aggregate

sources (sandstone and limestone) and four mixture types and polished by a three-wheel accelerated polishing device developed by the National Center for

Asphalt Technology (NCAT). The surface frictional characteristics of each slab were measured by Dynamic Fiction tester (DFT) and Circular Texture

Meter (CTM) at various pre-determined polishing cycles. In addition, an inventory dataset of field friction number (FN) measurements was obtained from

the LADOTD’s Materials Laboratory and analyzed in this study to determine the effects of traffic loading, aggregate and mixture types on the measured

FN values.

The laboratory results indicated that the accelerated polishing device used in this study performed just as the expectation; i.e., as the polishing cycle

increases, the measured frictional property of testing slab surface decreases. It was found that the DFT measurements were fairly sensitive to the coarse

aggregate types (related to micro-texture) used in mix design, but were not very sensitive to different mix types or aggregate gradations (related to macrotexture).

The analysis of CTM measured Mean Profile Depth (MPD) results confirmed a strong relationship between MPD and mixture type, indicating

MPD does reflect well of surface macro-texture. Because friction resistance of an asphalt mixture should account for both micro- and macro-texture, the

International Friction Index (IFI) friction numbers, the F(60), were determined based on an IFI model using measured DF20 (the DFT measurement at a

friction speed of 20 mi/hr) and MPD values for each slab tested. Further analysis of F(60) results generally indicated that an open-graded friction coarse

(OGFC) mix type considered in this study had the highest friction resistance due to its largest surface macro-texture (or MPD values), followed by the

stone matrix asphalt (SMA) mix type, and then by the two Superpave mix types considered (a 19-mm Superpave Level-II mix, a 12.5-mm Superpave

Level-II mix). The F(60) results also indicated that a selected sandstone type (AB13) with a high polishing resistance (PSV>37) performed significantly

better in terms of mixture friction resistance than a selected limestone (AA50) with an PSV of 31. Mixtures using an aggregate blend of 30 percent of

selected sandstone and 70 percent of the limestone tended to have a better surface friction resistance than those with 100 percent of the limestone. This

observation demonstrates that blending of low and high friction aggregates together can possibly produce an asphalt mixture with an adequate field friction

resistance.

The analysis has led to the development of a set of prediction models of mixture frictional properties, and a laboratory mix design procedure that

addresses the surface friction resistance of an asphalt mixture in terms of both micro- and macro- surface textures. The developed frictional mix design

procedure allows estimating a friction-demand based, design SN value for an asphalt mixture during the mix design stage.


Format:
PDF
Funding:
LTRC Project number: 09-2B ; SIO number: 30000119
LTRC Project number: 09-2B ; SIO number: 30000119 Less -
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:31bdbcba7e5453b169f91a52049178e1e26afd4b7bdf97eeaa112102c41b3f82
Download URL:
https://rosap.ntl.bts.gov/view/dot/24727/dot_24727_DS1.pdf
File Type:

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