hvs international alliance
TRANSCRIPT
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TRANSPORTATION Florida Department of
HVS International Alliance
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Florida Department of Transportation
Topics
• Recently completed HVS research • Planned HVS research (2015 to 2016) • Issues testing concrete
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Florida Department of Transportation
PG 76-22 (ARB)
• Objective: Validate newly developed PG 76-22 (ARB) specification – Three binder suppliers – Dense graded SP-12.5
Binder Producer
Binder Type
Modifier Mixture
ID A PG 76-22 (PMA) SBS PG 76-22 (PMA) A ARB-5 5% GTR ARB-5 A PG 76-22 (ARB) Min 7% GTR and SBS (Lower % GTR) Hybrid A-L A PG 76-22 (ARB) Min 7% GTR and SBS (Higher % GTR) Hybrid A-H B PG 76-22 (ARB) Min 7% GTR and SBS Hybrid B C PG 76-22 (ARB) Min 7% GTR GTR C
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Florida Department of Transportation
ARB History
• 1988: Solid Waste Management Act – Florida Statute 336.044 – Directed FDOT to research and adopt specs
where feasible • Contracted research with NCAT and UF • FDOT laboratory research
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Florida Department of Transportation
ARB History
• 1989 – 1991: Field Test Sections – SR 120, Alachua County – SR 16, Bradford County – I-95, St. Johns County
• 1992 – 1993 Worker Exposure Study – CR-39 Hillsborough
County
With ARB Without ARB
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Florida Department of Transportation
ARB History
• 1994: ARB specifications – ARB-5, ARB-12, & ARB-20 – Used in friction courses and interlayers
• Benefits – Conserves resources – Improves performance
• Cons – Issues with settlement
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Florida Department of Transportation
ARB History
• 2009: ‘Hybrid’ binder research with UF
• 2011: PG 76-22 (ARB) task group formed – Modernize specifications
• 2013: PG 76-22 (ARB) specification – Validation/refinement with HVS
and NCAT test sections
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Florida Department of Transportation
PG 76-22 (ARB) Specification
• PG 76-22 is met • Minimum 7% GTR by weight of binder • Polymer modification optional • Solubility not required for PG 76-22 (ARB) • Separation test, 15⁰F maximum • Multi-Stress Creep Recovery
– Jnr and % recovery – 2 mm gap
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Florida Department of Transportation
FDOT Spec Section 916
Test Test Temp., °C Specification Requirement
Original Binder Separation Test, Softening Point Difference, °F
N/A Max. 15°F
Flash Point, COC N/A Min 450°F Rotational Viscosity 135 Max 3 Pa•s1 DSR, G*/sin δ, @ 10 rad/s (with 2.00 mm gap)
76 Min 1.0 kPa
Phase Angle 76 Max. 75 degrees RTFO Residue
RTFOT, % Mass Change 163 Max ±1.000% MSCR(with 2.00 mm gap)
67 % Recovery, 3.2 kPa-1 %R3.2 ≥ 29.37(Jnr3.2)-0.2633
Jnr, 3.2 kPa-1 “V” grade =
Max 1.0 kPa-1 Jnr, % Difference Max 75%
PAV Residue DSR, G* sin δ, @ 10 rad/s 26.5 Max 5000 kPa BBR Creep Stiffness, S
-12 Max 300 MPa
BBR Creep Stiffness, m-value Min 0.300
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Florida Department of Transportation
Test Sections
1.5-inch SP-12.5
10.5-inch limerock base
12-inch granular subgrade
1-inch existing SP-12.5
1.5-inch SP-12.5
PG76-22 (PMA) 1 Lane
1.5-inch SP-12.5
10.5-inch limerock base
12-inch granular subgrade
1-inch existing SP-12.5
1.5-inch SP-12.5
ARB-5 1 Lane
1.5-inch SP-12.5
10.5-inch limerock base
12-inch granular subgrade
1-inch existing SP-12.5
1.5-inch SP-12.5
PG76-22 (ARB) Modified with GTR and SBS
Polymer 3 Lanes
1.5-inch SP-12.5
10.5-inch limerock base
12-inch granular subgrade
1-inch existing SP-12.5
1.5-inch SP-12.5
PG 76-22 (ARB) Modified with
GTR 1 Lane
2 binder suppliers 1 binder suppliers
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Florida Department of Transportation
Laboratory Binder Tests Test
Test Temp., °C
Hybrid A-L
Hybrid A-H
Hybrid B
GTR C
Specification Requirement
Original Binder Separation Test, Softening Point Difference, °F
N/A 11 17 6 26 Max. 15°F
Flash Point, COC N/A 500+ 500+ 500+ 500+ Min 450°F Rotational Viscosity 135 2.21 3.10 1.73 2.51 Max 3 Pa•s1 DSR, G*/sin δ, @ 10 rad/s (with 2.00 mm gap)
76 1.28 1.31 1.41 2.35 Min 1.0 kPa
Phase Angle 76 68.0 68.6 73.0 74.4 Max. 75 degrees RTFO Residue
RTFOT, % Mass Change 163 -0.118 -0.158 -0.160 -0.226 Max ±1.000% MSCR (with 2.00 mm gap)
67 % Recovery, 3.2 kPa-1 68.94 49.70 55.52 35.71 %R3.2 ≥ 29.37(Jnr3.2)-0.2633
Jnr, 3.2 kPa-1 0.322 0.559 0.297 0.357 “V” grade =
Max 1.0 kPa-1 Jnr, % Difference 17.93 54.52 24.30 21.92 Max 75%
PAV Residue DSR, G* sin δ, @ 10 rad/s 26.5 1580 1110 3190 3200 Max 5000 kPa BBR Creep Stiffness, S
-12 110 70 153 168 Max 300 MPa
BBR Creep Stiffness, m-value 0.358 0.385 0.300 0.299 Min 0.300 Notes: 1. FDOT allows binders with values higher than 3 Pa∙s to be used with caution and only after consulting with the suppler as to any special handling
procedures, including pumping capabilities. 2. MSCR test was not a requirement for PG 76-22 (PMA) at the beginning of the APT study.
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Florida Department of Transportation
HVS Performance
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Florida Department of Transportation
Laboratory Mixture Tests
Mixture ID
AMPT Properties Fracture Properties at 10 °C HVS Rut Depth,
mm Dynamic Modulus, ksi (1 Hz, 20 °C)
Flow Number
Fracture Energy (KJ/m3)
Creep Rate
(1/psi·sec)
Energy Ratio
Control 699 72 2.8 2.8E-09 4.2 5.9
ARB-5 573 60 5.4 6.8E-09 4.5 6.6
Hybrid A-L 421 97 5.0 9.5E-09 2.6 5.1
Hybrid A-H1 271 63 7.2 2.0E-08 2.5 4.4
Hybrid B 696 423 4.7 3.1E-09 6.6 3.9
GTR C2 657 382 2.7 2.3E-09 5.0 3.6 Notes: 1. Failed separation test and rotational viscosity 2. Failed separation test, MSCR % recovery, and BBR creep compliance
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Florida Department of Transportation
NCAT Test Sections
• Initiated during 2012 research cycle • Completed 10 million ESALs in Oct 2014
Test Track Section
Section Description
Rut Depth, mm
Cracked Area, %
Lane Right Wheel Path
Left Wheel Path
E7A PG 76-22 (PMA) 2.2 6 4 14 E7B PG 76-22 (ARB) 2.0 15 19 15
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Florida Department of Transportation
PG 76-22 (ARB) Summary
• All mixtures showed good rutting performance. Rutting resistance of PG 76-22 (ARB) mixtures was found to be comparable to that of mixture with a standard PG 76-22 (PMA).
• All mixtures exhibited a good range of ER values, which indicated good cracking resistance.
• Binders with a greater percentage of GTR (Hybrid A-H and GTR C) failed to meet the separation requirement.
• Adoption of a performance graded ARB specification replaces two ARBs (ARB-5 and ARB-12) with one (PG 76-22 (ARB)), which simplifies binder storage during HMA production.
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Florida Department of Transportation
SP-4.75 mixture
• Objective: Investigate the thickness of a SP-4.75 layer
1.5-inch SP-12.5 w/ PG 67-22
10.5-inch limerock base
12-inch granular subbase
4.75-mm mixture w/ PG 67-22
1.5-inch SP-12.5 w/ PG 76-22
4.75-mm w/ PG 67-22
1.5-inch SP-12.5 w/ PG 67-22
10.5-inch limerock base
12-inch granular subbase
1.5-inch SP-12.5 w/ PG 76-22 4.75-mm mixture w/ PG 76-22
4.75-mm w/ PG 76-22
• Thickness: – ½ inch, ¾ inch,
and 1 inch • JMF:
– 6.5% AC – 4 to 6% voids
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Florida Department of Transportation
Background
• Pavement preservation project on US-98 in Gulf County established in Fall 2012 – ½ and ¾ inch thick
• Five maintenance patches in District 3 – Less than 0.5 miles long
• District 1 considering SP-4.75 for a project to optimize layer thickness and milling depth options
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Florida Department of Transportation
Rutting Resistance
0.0
2.0
4.0
6.0
8.0
10.0
12.0
0.5 inch 0.75 inch 1 inch
Rut D
epth
, mm
SP-4.75 Thickness
Rut Depth after 100,000 Passes
SP-4.75 with PG 67-22 SP-4.75 with PG 76-22 SP-12.5 with PG 76-22
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Florida Department of Transportation
Cracking Resistance
0.0
2.0
4.0
6.0
8.0
10.0
12.0
SP-12.5 (PG 67-22) SP-12.5 (PG 76-22) SP-4.75 (PG 67-22) SP-4.75 (PG 76-22)
Ener
gy R
atio
at 1
0⁰C
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Florida Department of Transportation
SP-4.75 Summary
• Layer thicknesses of ¾ inch and 1 inch had similar rut resistance of a SP-12.5 when PG 76-22 asphalt binder was used
• SP-4.75 with PG 76-22 was found to have better cracking resistance than SP-12.5 with PG 76-22
• Interest building in using a SP-4.75 as a crack relief interlayer
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Florida Department of Transportation
Topics
• Recently completed APT research • Planned APT research (2015 to 2016) • Concrete Test Road update
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Florida Department of Transportation
Planned APT Research
• FC-5 thickness • Asphalt segregation • Asphalt density • Tack coat rate effect on cracking
resistance • High polymer binder
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Florida Department of Transportation
FC-5 Thickness
• Background: FC-5 is typically placed at ¾ inch thickness, but may be placed thicker due to design & construction issues
• Objective: Determine rut resistance of thicker FC-5 lifts
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Florida Department of Transportation
FC-5 Thickness
• PG 76-22 & PG 82-22 binders 12.5 mm NMAS
• Placed at ¾, 1-¼, and 2 inches thick
• Two 400 ft. lanes
1.5-inch SP-12.5 w/ PG 76-22
10.5-inch limerock base
12-inch granular subbase
1.5-inch SP-12.5 w/ PG 76-22 FC-5 Variable thickness
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Florida Department of Transportation
Asphalt Segregation
• Objective: Quantify the reduction of pavement life due to asphalt segregation. – Develop/refine methods
to identify segregation using texture measurements
Severe Segregation
No Segregation
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Florida Department of Transportation
Asphalt Segregation
• Segregation Identification – Circular track meter – TM2: wide spot laser – FTM: in-house laser texture meter – Cores – IR Camera
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Florida Department of Transportation
Asphalt Density
• Objective: Provide guidance to inspectors when to remove and replace low density sections
• Three target densities – 87%, 90%, and 93%
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Florida Department of Transportation
Tack Coat Rate • Background: Top-down cracking is one of
the primary distresses in Florida. Recent research has suggested that inadequate tack coat rates may be contributing to crack development.
• Objective: Evaluate effect of tack coat rate on cracking resistance.
• Three residual tack coat rates – 0.02 gal/sy, 0.04 gal/sy, 0.06 gal/sy, and – one unbonded section
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Florida Department of Transportation
Tack Coat Rate
• Estimating longitudinal application rate of asphalt distributors in gallons per square yard in accordance with ASTM test method D 2995 – Test Method A – Pre-weighed geotextile pads
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Florida Department of Transportation
High Polymer Binder
• Objective: Evaluate a high polymer binder for use at localized sections with a history of rutting and/or cracking
• Two binder contents will be evaluated – Design AC content – Design AC content + 0.5%
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Florida Department of Transportation
Topics
• Recently completed APT research • Planned APT research (2015 to 2016) • Issues testing concrete
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Florida Department of Transportation
Concrete Testing
• The HVS casts a large shadow
• Temperature gradients and environmental strain are minimized
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Florida Department of Transportation
Recent Concrete Pavement Results
• Two instrumented slabs • Slab 1 was in full sun • Slab 2 was in the HVS
shadow
Slab 1 in the sun
Slab 2 in the HVS shadow
Thermocouple Tree & Strain
Gauges
Thermocouple Tree & Strain
Gauges
1 inch below the surface
1 inch above the base
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Florida Department of Transportation
Temperature Near Slab Surface
HVS shadow reduced peak temperature near the slab surface by 10⁰C
10
15
20
25
30
35
40
3/23/0:00 3/23/12:00 3/24/0:00 3/24/12:00 3/25/0:00 3/25/12:00 3/26/0:00
Tem
pera
ture
(°C)
Time (M/D/H)
Slab1 in the sun Slab2 in the HVS shadow Ambient Temperature
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Florida Department of Transportation
Temperature gradient of the slab in the HVS shadow is nearly 0⁰C
-5
0
5
10
15
3/23/0:00 3/23/12:00 3/24/0:00 3/24/12:00 3/25/0:00 3/25/12:00 3/26/0:00
Tem
pera
ture
(°C)
Time (M/D/H))
Slab1 in the sun Slab2 in the HVS shadow
Temperature Gradient
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Florida Department of Transportation
Environmental Strain
-30
-20
-10
0
10
20
30
40
50
60
0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
Mic
ro st
rain
(Rel
ativ
e)
Time (hour)
Vibrating Wire Gauge Near Slab Surface
Shade Sun
-30
-20
-10
0
10
20
30
40
50
60
0:00 3:00 6:00 9:00 12:00 15:00 18:00 21:00 0:00
Mic
ro st
rain
(Rel
ativ
e)
Time (hour)
Vibrating Wire Gauge Near Slab Bottom
Environmental strain due to curling is 20 to 30 microstrain less when shaded
Shade Sun
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Florida Department of Transportation 37
Benefits from Florida’s Accelerated Pavement Testing
Program
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Florida Department of Transportation
Research Project Selection
• APT program integrated with overall research effort – Planning, development & execution of research
projects performed on an annual basis • Research projects solicited from FDOT’s offices,
industry, & academia – Critical issues that should be addressed through APT – Critical issues not applicable to APT but should be
performed with in-house resources – Critical issues that should be addressed through a
contracted research effort
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Florida Department of Transportation
Major Research Projects
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• 2001 - Evaluation of Superpave mixtures with and without polymer modified binders
• 2003 - Assessment of the appropriate APT loading condition
• 2004 -Evaluation of early strength requirement of concrete for slab replacement
• 2005 - Evaluation of coarse and fine graded Superpave mixtures
• 2006 - Evaluation of a thin concrete overlay of an asphalt pavement
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Florida Department of Transportation
Major Research Projects
• 2007 - Development of methodologies to assess cracking potential of asphalt mixtures
• 2008 - Evaluation of asphalt strain gauge repeatability
• 2009 - Impact of wide-base tires on pavement damage
• 2011 – Evaluation of an ARMI to mitigate reflection cracking & resist rutting
• 2011 – Evaluation of a PG 82-22 asphalt binder
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Florida Department of Transportation
Impact of APT Research
• Revision of pavement design and construction methods and specifications – Implementation or discontinued use of
researched materials and methods • Informed policy decision making • Furthering knowledge/education of
pavement engineers
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Florida Department of Transportation
SOME EXAMPLES OF BENEFITS
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Florida Department of Transportation
Benefits of Polymer Modified Binder
• First APT experiment evaluated SBS polymer modified binder – Two layers of SBS modified PG 76-22 binder – One layer of SBS modified PG 76-22 binder – Two layers of unmodified PG 67-22 binder
• Rate of rutting for pavement with unmodified binder approximately twice that of the pavements with modified binder
• Two layers of modified binder performed slightly better than one layer
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Florida Department of Transportation
Benefits of Polymer Modified Binder Research
• 2011 data: Resurfacing ~ $125,000 per lane mile
• ~ 500 lane miles of Traffic Level D and E mixes placed each year
• Assuming 2 more years of life, the reduction in annualized cost is $1,000 per lane mile, or ~$500,000 per year
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Florida Department of Transportation
Benefits of Polymer Modified Binder Research • FDOT specifies PG 76-22 for the final two
structural courses in traffic level E mixtures but only the top structural course in traffic level D mixtures
• ~ 450,000 tons of traffic level D mix placed each year
• Use of modified binder for top layer only equals 50% savings on total initial cost of polymer, ~$2.1M per year (2011 HMA cost data)
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Florida Department of Transportation
Benefits of Allowing Fine Graded Mixtures • Based on initial Superpave guidelines, FDOT
specified use of coarse graded mixtures to provide better rutting resistance
• A 2004 APT study showed that fine graded mixtures performed as well as coarse graded mixtures
• In 2005, FDOT allowed fine graded mixtures for traffic levels D and E mixtures
• According to industry, a cost savings of $2 to $5 per ton of asphalt mix, ~ $1.5M per year by allowing fine graded mixes
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Florida Department of Transportation
Other Recent Projects • Impact of wide-base tires, 2010
– APT study that showed new generation wide-base tires produced similar pavement damage as dual tires
• Discontinue routine use of ARMI, 2012 – Ineffective at mitigating reflection cracking – Contributes to instability rutting – Initiated research project to identify alternatives
• Implementation of High Polymer Modified Binder, 2012 – Pavements with historically high rutting – Two projects recently constructed
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Florida Department of Transportation
Educational Benefits
• Collaborate with Florida universities • Several graduate level research efforts
have used APT data – 1 Master’s Degree – 8 PhD’s
• Students work on-site and assist with APT research
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Florida Department of Transportation
Summary
• APT is a critical component of FDOT’s pavement research program
• Key to success is the careful selection of research projects that address critical issues
• Technology transfer is essential
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Florida Department of Transportation
Questions?
APT Website: http://www.dot.state.fl.us/statematerialsoffice/pavement/research/apt/index.shtm