Virginia’s Experience with High Friction Surface Treatments

2015 AASHTO/TRB Conference on Transportation Infrastructure Maintenance and Operations. Des Moines, Iowa, July 19 – July 23, , 2015

Michael Sprinkel, PE., Associate Director, VCTIR Kevin K. McGhee, PE., Associate Principal Scientist, VCTIR

Edgar David de León Izeppi, Senior Research Associate, VTTI

Introduction • High Friction Surface (HFS) treatments are an

application of epoxy and aggregate to roadway surfaces to provide a very high degree of skid resistance.

• HFS treatments may be particularly effective when used where a high risk and/or record of crashes may be related to lower skid resistance.

• HFS treatments are one of the FHWA “Every Day Counts” initiatives

Introduction, continued • In 2012 and 2014 the Virginia Department of

Transportation placed HFS materials at 9 locations that met this description.

• This presentation provides information on the construction, skid resistance, bond strength, early age condition, and cost of the Virginia HFS treatments.

2012 Installations (August)

Site County Route Treated Curves

HFST area, yd2

1 Essex 618 11 7,338

2 Gloucester 605 12 4,470 3 Chesterfield 630 1 700

4a Southampton 58 WB 1 4,667

4b Southampton 58 EB 1 4,667

Total HFST area: 29,346 yd2

2014 Installations (9-22 thru 11-9)

Site County Route Treated Curves

HFST area, yd2

1 Mecklenburg 903 9 15431 2 Brunswick 712 2 1844 3 Gloucester 605 3 4600 4 Caroline 639 4 6011 5 Chesterfield 602 & 643 9 15784

Total HFST area: 43,670 yd2

Objective of Research

• This study evaluates HFS as an alternative for increasing the skid resistance of sections of asphalt pavement on rural roads that have a high risk of vehicle crashes. The specific objective was to provide information on the construction, skid resistance, bond strength, early age condition, and cost.

Materials, Methods and Tasks • A special provision was prepared for use in the

contract for constructing the HFS treatments, • 2012 sites were tested for skid resistance

(friction) after approximately 6 months using a continuous friction-testing device. 2014 sites were tested within 2 months of construction using a lock wheel tester (ASTM E274).

• 2012 sites were visually inspected after approximately 10 and 23 months. 2014 sites were inspected after approximately 1 to 2 months. Pictures were taken.

Materials, Methods and Tasks, continued

• For the 2012 installations three 4-in diameter cores were extracted from 4 of the 5 sites after approximately 10 months in service and tested for bond strength in the laboratory using a modified version of ASTM C1583.

• Three 2-in diameter cores were extracted from the 2014 sites approximately 1 to 2 months after the installations (ASTM C1583 modified).

Friction Testing

• Special provision requires a minimum acceptable skid resistance of 55 as measured using Virginia Test Method 122, which applies a locked-wheel friction tester (ASTM E274) equipped with a smooth tire (ASTM E524).

• Unfortunately, the nature of most applications of HFS (i.e., rural, sharp curves) made testing with a full lock-up device at 40 mph (the standard test speed) difficult.

Friction Testing

• A Findlay Irvine Grip Tester (GT) was used to measure continuous skid resistance along the right wheel path of the travel lane of the 2012 test sections.

• The GT system is a fixed slip device in which the test tire is connected to the trailer wheel axle by a chain, allowing it to measure the rotational resistance of a constantly slipping smooth tire (ASTM E2340).

• Measurements were taken every 3 ft at 40 mph using a constant water film thickness of 0.02 inch.

Contacts:

If you are interested in the GripTester loan program for your state, contact your FHWA resource center, division office, or Bob Orthmeyer of the Federal Highway Administration by phone at (708) 283-3533 or by email: robert.orthmeyer@dot.gov

or contact Mark Swanlund at (202) 366-1323 or by email: mark.swanlund@dot.gov.

The program is administered by the Virginia Tech Transportation Institute, if you need additional information, contact Gerardo Flintsch at (540) 231-1569 or by email flintsch@vt.edu.

FHWA GRIPTESTER® Surface Friction

(Skid Resistance) Tester Equipment Loan Program

Special Provision Binder is a two part exothermic epoxy resin

Property Requirement Test Method Viscosity 7 – 70 poises ASTM D2169 Gel Time 10 minutes min. D2471 Comp Str with agg @ 24 hrs 5,000 psi min. D695 Tensile Str neat @ 7 days 2,000 – 5,000 psi D638 Elongation neat @ 7 days 30 per cent min. ASTM D638 Adhesive strength @ 24 hrs 250 psi minimum ASTM C 1583 Water Abs neat @ 24 hrs 1.0 per cent max. D570 Cure for Traffic 3 hours max Thin Film @ 75°F

Special Provision Aggregate must be Bauxite that is clean, dry, free

from foreign matter and meet the following requirements: Property Requirement Test Method

Polish Sus.(Micro-Deval) 5% Loss (max) AASHTO T327 AAV (Agg. Abras. Value) 20% max AASHTO T96 Aggregate Gradation, Per cent passing No. 6 Per cent passing No. 16

95 – 100 %

AASHTO T27

0.0 – 5.0% Texture (sandpatch) 1.0 mm (min) ASTM E-965 Skid Resistance (SN40S) 55 (min) VTM 122* * locked-wheel friction tester (ASTM E274) equipped with a smooth tire (ASTM E524)

Special Provision • Asphalt surfaces must be clean, dry, and free

of all dust, oil, debris and any other material that might interfere with the bond between the epoxy resin binder material and asphalt surface

• Air temperature: VDOT above 60F, Others above 40F

• New asphalt must be older than 30 days • Automated continuous application equipment

for application of epoxy and aggregate.

Special Provision • A minimum epoxy binder application rate of

10 gal/per minute with a minimum uniform application thickness of 50 mils

• Cured until vacuuming or brooming to remove loose aggregate can be performed without tearing or damaging the surface

• Loose aggregate removed prior to opening to traffic

2012 Installation

Pictures: Richard J. Baker DBI Services

Bauxite aggregate

2014 Installation

Bauxite aggregate

Results Skid Resistance Route 618

Results Skid Resistance Route 605

Results Skid Resistance Route 630

Results Skid Resistance Route 58 WB

Results Skid Resistance Route 58 EB

Skid Resistance 2014 Installations

Site County Route LWT SN Avg. LWT SN

5 Mecklenburg 903 83 - 98 88

6 Brunswick 712 76 - 86 81 7 Gloucester 605 79 - 87 83 8 Caroline 639 9 Chesterfield 602 83 - 92 88 9 Chesterfield 602 68 - 84 76 9 Chesterfield 643 74 - 75 75

Underlying Pavement Condition 2012 Locations

Site County Route Condition Rating (CCI)

Rating Year

1 Gloucester 605 56 2009

2 Essex 618 66 2008 3 Chesterfield 30 89 2008 4a Franklin 58 Bus WB 60 2012 4b Franklin 58 Bus EB 67 2012

Underlying Pavement Condition 2014 Locations

Site County Route Condition Rating (CCI)

Rating Year

5 Mecklenburg 903 good to fair 6 Brunswick 712 good 7 Gloucester 605 good to poor 8 Caroline 639 good to new 9 Chesterfield 602 & 643 good to poor

The surfaces appeared to be in good condition (site 3)

Lost aggregate at site 2

A few spalls, reflected cracking, and minor pumping were noted on US58

Poor quality asphalt at site 2.

Tensile Failure in Asphalt in core from 2012 site 1, VTM 128

Bond strength 2012, psi

Site Core1 Core 2 Core 3 Average Failure 1 26 35 20 27 asphalt 2 38 31 46 38 asphalt 3 - - - - - 4a 15 50 88 51 asphalt 4b 12 8 13 11 asphalt

Bond Strengths exceed the strength of the asphalt.

Quality asphalt has a tensile strength of approximately 100 psi

Tensile Failure in Asphalt in cores from 2014 sites, VTM 128

Bond strength 2014, psi

Site Core1 Core 2 Core 3 Average Failure 5 139 108 92 113 asphalt 6 47 37 54 46 asphalt 7 94 42 65 54 asphalt 8 44 68 107 73 asphalt 9 46 54 40 47 asphalt

Bond Strengths exceed the strength of the asphalt.

Quality asphalt has a tensile strength of approximately 100 psi

Cost and Friction numbers Alternative Cost, $/yd2 Friction number HFS (2012) 27 GT 1.0 to 1.1 HFS (2014) 29 LW T 75 - 88

Conclusions

1. The Virginia HFS installs were successfully constructed. 2. The materials were of high quality and bond strength

exceeded the tensile strength of the asphalt. 3. Friction numbers significantly exceeded the minimum LWT

number of 55. 4. The poor quality of the asphalt at 2012 sites 1, 2 and 4a is

influencing the surface condition of the HFS after 23 months. 5. HFS materials may provide an effective tool in a system-wide

pavement friction management program, but they will only perform as long as the structure that supports them.

6. Use of continuous friction measurement equipment (CFME) seems particularly appropriate for managing HFS applications.

Thank you. Questions?

Virginia’s Experience with High Friction Surface Treatments