Transcript Slide 1

3rd International Road Surface Friction Conference
SAFER ROAD SURFACES – SAVING LIVES
May 2011 Queensland
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Innovative Surfacing Treatments
Delivering Safer Roads
Gerard Killick
Spray and Blending Divisional Manager
Jeff Waters
Surfacing Development Engineer
Dr Bryan Pidwerbesky
General Manager – Technical
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Outline
 Background – why did Fulton Hogan develop
these new technologies?
 MultiSpray® variable transverse bitumen
application
 Ultra high pressure watercutter
 PAVEtex thin, textured gap graded asphalt
mixes
 Conclusions
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Why did Fulton Hogan develop
these new technologies?
 Changes to road asset management since
1995
 All road construction & maintenance activities
in New Zealand had to be outsourced
 Emphasis on providing appropriate level of
skid resistance to reduce accidents
 Constrained road maintenance budgets
 Encouraged innovation by industry
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One Problem
 Texture variation is a major difficulty
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Another Common Problem
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Micro- vs Macro-texture
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Old Solutions to Texture Variation
 Strip sealing, or
 Two passes of sprayer of differing application,
one for shoulders and centreline, another for
the wheelpaths
 Two sprayers are used on extreme sites
 Objective: “uniform” texture across the
pavement from which to start again
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Voids in Seal Coats
Bitumen
Binder
Unfilled voids
Chip
Average Least
Dimension
(ALD)
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Needed New Solutions
 In 1996 Fulton Hogan started a major
upgrade of its chip sealing capability
– Sprayers and Chip Spreaders.
 Next generation of chip sealing:
– Variable application of binder & chip
– Automated texture measurement
– Computerised data output/control
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Applications
 Preventative:
Reseals on high trafficked
chip seals. Optimum binder
in wheelpaths
 Corrective:
One pass spraying on seals
with flushed wheelpaths &/or
coarse shoulders
 Optimised :
Spray run widths
sites where traffic islands /
pedestrian islands require
variable spray width
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Extending Seal Life on Low Volume
Roads Using Variable Distribution
 Reducing risk of:
– Flushing in wheeltracks
– Stripping between &
outside wheelpath
 Field Trials since 1999
 Verified design algorithm
for MultiSpray variable
application rate
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Field Application captured on carpet strips
25
15
10
5
Mean
4 Pad Mean
Mean + 20%
Mean - 20%
Mean + 12%
Mean - 12%
87
84
81
78
75
72
69
66
63
60
57
54
51
48
45
42
39
36
33
30
27
24
21
18
15
12
9
6
0
3
Grams of Binder
20
Pad
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Transverse Variable Binder
Application Rates
LS
LOWP
LMid
LIWP
CL
RIWP
RMid
ROWP
RS
Design
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
Control Nth
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
Trial 1
2.28
1.82
2.06
1.82
2.06
1.82
2.06
1.82
2.28
Trial 2
2.09
1.67
1.88
1.67
1.88
1.67
1.88
1.67
2.09
Trial 3
2.45
1.47
2.10
1.47
2.10
1.47
2.10
1.47
2.45
Control Sth
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
1.90
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Texture Depth (MPD, mm)
4.0
3.5
3.0
2.5
2.0
1.5
Control Nth LWP 1.90l/m²
Section 1 LWP 1.82l/m²
Section 2 LWP 1.67l/m²
Section 3 LWP 1.47l/m²
Control Sth LWP 1.90l/m²
1.0
2001 2002 2003 2004 2005 2006 2007 2008 2009 2010
Year
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Variable transverse application of binder
Less binder is sprayed in
wheel tracks, with no chip
loss:
At least 10% less for
unflushed sites
At least 20% less for
flushed sites
Reduces the use of non-renewable resource (bitumen)
Extends the texture depth life of chip seals
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Conclusions & benefits
 By applying correct amount of bitumen from first
reseal, varied across the width of the lane, flushing is
prevented
 Improved safety when sealing
 Easier for traffic control & to work around fixtures
such as poles & curbs
 Improved quality
 Improved productivity
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Ultra High Pressure Watercutting
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Background
 Developed in NZ in
early 2000
 Environmentally friendly
 Much safer than hot /
solvent alternatives
Watercut
Uncut
Bitumen burning being performed prior to the
development of the watercutter
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Effect on Chipseal Surface
•
•
Cuts away unwanted excess bitumen, restoring texture and vastly improving
hysteresis and adhesion friction.
Water energy dissipated on contact with seal aggregate and doesn’t dislodge
chip.
Before
After
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Re-texturing Asphalt
• Removes a very small amount
of fines as well as excess
binder from the surface to
expose the aggregate.
• This increases surface texture.
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Early Trials
Cut Section
Uncut Section
View north from uncut section Feb 06 Christchurch, South Island
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0.60
2
1.6
1.2
0.50
0.8
0.40
0.4
0.30
1998
Section 1 Friction Watercut January 02
Section 2 Friction (uncut)
Section 3 Friction Watercut August 02
Section 1 Texture Watercut January 02
Section 2 Texture (uncut)
Section 3 Texture Watercut August 02
2000
2002
2004
2006
2008
Texture (mm)
Friction (SFC)
0.70
Watercut Section 3 August 2002
Watercut Section 1 January 2002
0.80
0
2010
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Land Transport New
Zealand Research
Project:
Investigating the
Lifecycle of Water Cutter
Rejuvenation of
Aggregates
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Reasons for the Project
 How long does the improvement last?
 Sustainability
 Recycling the surface
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Site Descriptions
 Sites were deficient in friction but not texture
(surface stones were polished, but no
bleeding)
 Varied climate
 Varied Aggregate: Greywacke, Schist, basalt,
sandstone, gneiss
 Varied Surfacing types: single coat, two coat,
AC, Open Graded Porous Asphalt
 Various geometry and traffic levels.
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Conclusions
 Watercutting improved microtexture & macrotexture
of polished surfaces
 Microtexture improvement can last > 5 years
 Watercutting does not sharpen up rounded edges on
worn surfaces
 Watercutting is a cost effective resurfacing treatment
but is not a cure all for flushing, bleeding and
polishing problems
 Sections identified as deficient by skid resistance
survey can be made safe until resurfacing
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PAVEtex UTA 12mm
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What is PAVEtex UTA?
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Cost-effective
 Laid 15mm thick is
significantly lower cost
than mix laid 25-30mm
thick.
 Thicker binder film
thickness ensures more
durable so longer life than
OGPA or AC10mm mix on
flexible pavements.
 Lasts longer than chip
seals in high stress
situations.
 Doesn’t waste high value
high PSV aggregate by
burying them in the body
of the mix.
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Environmentally Friendly
 Reduced use of nonrenewable resource
compared with other TA
surfacings.
 Reduced use of nonrenewable resource when
compared with multiple
short lived seals.
 Lower noise than chipseal
and asphaltic concrete
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Variety of Applications
 Bridge decks
 High stress bends
 Wet, damp, shaded
areas
 Rural intersections
 Industrial areas
 Motorways
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Conclusions
PAVEtex UTA:
 Is a cost effective solution based on life cycle
costing.
 Provides adequate texture depth that provides
good skid resistance
 Is not suitable for sites with significant
flushing or extreme stress
 Is not waterproof when laid 15-20mm thick - a
membrane seal or heavy tack coat underneath
would minimise water ingress.
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Innovative Surfacing Treatments
Deliver Safer Roads
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