HVS International Alliance

TRANSPORTATION Florida Department of

HVS International Alliance

Florida Department of Transportation

Topics

• Recently completed HVS research • Planned HVS research (2015 to 2016) • Issues testing concrete


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


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


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


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


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


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


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


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




1.5-inch SP-12.5

ARB-5 1 Lane

1.5-inch 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




1.5-inch SP-12.5

PG 76-22 (ARB) Modified with

GTR 1 Lane

2 binder suppliers 1 binder suppliers


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.


HVS Performance


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


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


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.


SP-4.75 mixture

• Objective: Investigate the thickness of a SP-4.75 layer

1.5-inch SP-12.5 w/ PG 67-22


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



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


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


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


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


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


Topics

• Recently completed APT research • Planned APT research (2015 to 2016) • Concrete Test Road update


Planned APT Research

• FC-5 thickness • Asphalt segregation • Asphalt density • Tack coat rate effect on cracking

resistance • High polymer binder


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


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



1.5-inch SP-12.5 w/ PG 76-22 FC-5 Variable thickness


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


Asphalt Segregation

• Segregation Identification – Circular track meter – TM2: wide spot laser – FTM: in-house laser texture meter – Cores – IR Camera

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Asphalt Density

• Objective: Provide guidance to inspectors when to remove and replace low density sections

• Three target densities – 87%, 90%, and 93%


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


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


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%


Topics

• Recently completed APT research • Planned APT research (2015 to 2016) • Issues testing concrete


Concrete Testing

• The HVS casts a large shadow

• Temperature gradients and environmental strain are minimized


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


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


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


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

Florida Department of Transportation 37

Benefits from Florida’s Accelerated Pavement Testing

Program


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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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


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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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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SOME EXAMPLES OF BENEFITS

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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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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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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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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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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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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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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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Questions?

APT Website: http://www.dot.state.fl.us/statematerialsoffice/pavement/research/apt/index.shtm

http://www.dot.state.fl.us/statematerialsoffice/pavement/research/apt/index.shtm

HVS International Alliance

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