1. Field Performance of Foaming Warm Mix Asphalt Pavement
(Paper Number: )
Shenghua Wu1, Weiguang Zhang2, Shihui Shen3, Balasingam Muhunthan4
1 University of South Alabama, Mobile AL; 2 Southeast University, Nanjing China; 3 Penn State University, Altoona PA;
4 Washington State University, Pullman WA
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Projects Information
National Cooperative Highway Research Program A.
Dr. Ed Harrigan and panel members, Braun Intertec, Inc. and Bloom Companies, LLC, partner universities and state DOTs
The water-containing foaming can reduce production temperature slightly more than the water-based foaming by 6 to 8°C.
HMA has slightly higher asphalt content than Foaming. The water-containing foaming has slightly higher asphalt content than the water- based foaming, but the difference is quite limited.
The use of studded tire and chain in some western states during winter, longer pavement service time, and high traffic volume, may result in polishing of aggregates and make them finer than their original design.
Foaming pavement showed slightly more wheel-path longitudinal cracking than the HMA pavement. A slightly higher asphalt content would be beneficial for the long-term fatigue performance.
The water-based foaming pavement showed comparable transverse cracking performance with HMA pavement. The optimal pavement maintenance time would be at the year 4-5.
Similar rutting performance between Foaming and HMA. Slightly higher in-place air void of foaming than HMA pavement seemed to have no significant effect on the long-term rutting distress.
Conclusions
Rutting
FIGURE 11 In-place air void versus 2nd round rut depth.
Acknowledgements
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(b)
FIGURE 12 Second-round rut depth with pavement age: (a) HMA vs. Water-containing foaming and (b) HMA vs. Water-based foaming.
Introduction
FIGURE 3 Boxplot for reduced production temperature (HMA minus WMA).
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FIGURE 6 Extracted aggregate gradation for some projects
Volumetric Results
1st Quartile
3rd Quartile
Median
FIGURE 4 Boxplot for asphalt content difference (HMA minus WMA).
FIGURE 5 Boxplot for in-place air void content difference (HMA minus WMA).
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Field Performance
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(b)
FIGURE 7 In-place air void versus (a) 1st round longitudinal crack length, (b) 2nd round longitudinal crack length.
FIGURE 8 Longitudinal crack length with pavement age: (a) 2nd round HMA vs. Water-containing, and (b) 2nd round HMA vs. Water-based.
Longitudinal Cracking
Transverse Cracking
FIGURE 9 In-place air void versus (a) 1st round transverse crack length, (b) 2nd round transverse crack length.
FIGURE 10 Transverse crack length with pavement age: (a) 2nd round HMA vs. Water-containing, and (b) 2nd round HMA vs. Water-based.
Project
Foaming WMA
Paving Date
Production Temp. (°C)
Traffic
AADT
Binder PG
NMASin.
Overlay Thickness/
Pavement Structure
1st Round Survey
2nd Round Survey
PA SR 2006
Advera
5/09
H (154)
W (127)
523
64-22
3/8
1.5 in.
Full depth
6/21/12
10/7/14
NE US 14 08
H (166)
W (135)
2,140
64-28
1/2
3 in.
10/14/12
9/11/14
TN SR 46
10/07
H (168)
W (121)
4440
70-22
1.25 in.
7/14/12
10/23/14
CO IH 70
7-8/07
H (146)
W (118)
30,000
58-28
2.5 in.
10/18/12
9/9/14
OH SR 541
Aspha-min
9/06
H (160)
6520
6/18/12
10/6/14
MO Hall St.
5/06
21,000
1.75 in.
Composite
7/16-18/12
9/24/14
WA SR 12
Aquablack
4/10
H (163)
6,550
8/28/12
9/16/14 NV
Ultrafoam
8/10
5,000
6 in.
Full-depth
10/19/12
9/8/14
VA I-66
Astec DBG
7/10
H (158)
W (142)
57,000
76-22
6/26/12
10/28/14
IL 147
6/10
H (149)
W (132)
775
7/19/12
7/29/14
PA SR 2012
Low Energy Asphalt
5-6/09
W (125)
254
6/20/12
Gencor LA
116
Foam
3/10 NA
2600
5/21/13
2/10/15
TX SH 251
8/08
2,300
2 in.
2/5/13
4/17/15
LA 3191
11/08
ADT 200
Foamed asphalt or foaming technology were originally used in asphalt stabilization in Iowa by Professor Csany in the 1950s. When hot asphalt meets water, the volume of asphalt is extensively increased by the water steam, creating a bubbled “foam” and resulting in reduced viscosity of asphalt but an improved workability and coatability of mixes. In recent years, foaming warm mix asphalt (WMA) have been widely used:
Water-based technology: 100% water, e.g. Astec DBG, Water Injection, and AquaBlack
Water-containing additive: zeolite particles containing 20% water, e.g. Aspha-min and Advera
Most research focused on laboratory produced mixes or short-term aged samples. Few studies have extensively evaluated the long-term field performance of foaming WMA pavement. Whether the foaming WMA can work similarly as hot mix asphalt (HMA) needs a field performance validation for confident use of such technology.
Note:
H- HMA, W- WMA, AADT-annual average daily traffic, ADT-average daily traffic, NMAS-nominal maximum aggregate size, NA-not available.
Objectives
To evaluate the field performance of foaming WMA pavements as compared to HMA control pavement in terms of cracking and rutting distresses, and
To investigate volumetric properties (asphalt content, in-place density, and aggregate gradation) for both field mixtures, in a relation with field distresses.
Field Survey
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FIGURE 1 Distribution of 16 field projects that contained foaming technologies
FIGURE 2 (a) Wheel-path longitudinal crack, (b) core taken at the tip of longitudinal crack, (c) transverse crack: reflective, (d) transverse crack: surface initiated