Details:

Creators:
Williams, Stacy G.
Corporate Creators:
University of Arkansas, Fayetteville. Dept. of Civil Engineering
Subject/TRT Terms:
[+]
Asphalt Mixtures Fine Aggregates Friction Course Friction Materials Pavement Layers Surface Active Agents
Publication/ Report Number:
MBTC 2066
Resource Type:
Tech Report
Geographical Coverage:
Arkansas
Edition:
Final report; June 2008
Corporate Publisher:
University of Arkansas, Fayetteville. Dept. of Civil Engineering
NTL Classification:
NTL-HIGHWAY/ROAD TRANSPORTATION-Materials;NTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and Performance;NTL-HIGHWAY/ROAD TRANSPORTATION-Design;
Abstract:
Skid resistance is generated by the development of friction between the vehicle tire and

roadway surface, and is partially dependent upon the characteristics of the pavement

texture. Microtexture and macrotexture are the critical components of pavement surface

friction. Microtexture is the dominant characteristic at low speeds, and at high speeds,

microtexture and macrotexture are both necessary. While these parameters are very

important, neither is considered during the design of an asphalt mix.

In this project, mixture design parameters were investigated to determine what features

of 4.75mm hot-mix asphalt (HMA) mixtures significantly influenced skid resistance. The

British Pendulum Test (BPT) was used to quantify microtexture, and a sand patch test

(modified for laboratory use) was used to measure macrotexture in terms of texture

depth. Mixture properties and aggregate properties were also analyzed in order to

develop relationships and guidelines for producing skid resistance during the design

phase of an HMA construction project. Additional considerations involved comparisons

with traditional surface mixes of larger nominal maximum aggregate size, and the effects

of aging and wear on the long-term skid resistance of 4.75mm mixtures.

In general, mixture properties did not provide significant relationships to skid resistance

(microtexture or macrotexture). Aggregate properties, however, did significantly

correlate to measures of macrotexture. Specifically, the most influential variables were

fine aggregate angularity, percent passing the #30 sieve, bulk specific gravity of the

aggregate blend, and two-dimensional particle shape (as measured by the Aggregate

Imaging System). Aggregate gradation was also significant in that a gap-graded

aggregate blend appeared to increase both microtexture and macrotexture.

When compared to 9.5mm and 12.5mm mixes, the 4.75mm mixes possessed the

greatest levels of microtexture. Thus, it was concluded that 4.75mm mixes did provide

adequate skid resistance for low-speed roadways. The macrotexture of 4.75mm mixes

was significantly less than that for a more traditional 12.5mm surface mix. Thus, if

4.75mm mixes are desired for use on high-speed roadways, the effects of roadway

geometry on pavement drainage should be carefully considered.


Format:
PDF
Collection(s):
US Transportation Collection
Main Document Checksum:
[+]
urn:sha256:2d489650106b83e78cdfbe08d696033590070f0558e3470afedff1f06a7c4b45
Download URL:
https://rosap.ntl.bts.gov/view/dot/17013/dot_17013_DS1.pdf
File Type:

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