Communication Product Updates, September/October 2003 Public Roads

Below are brief descriptions of products recently published online by the Federal Highway Administration's (FHWA) Office of Research, Development, and Technology. Some of the publications also may be available from the National Technical Information Service (NTIS). In some cases, limited copies are available from the Research and Technology (R&T) Report Center.

When ordering from NTIS, include the NTIS publication number (PB number) and the publication title. You also may visit the NTIS Web site at www.ntis.gov to order publications online. Call NTIS for current prices. For customers outside the United States, Canada, and Mexico, the cost is usually double the listed price. Address requests to:

National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-605-6000
Toll-free number: 800-553-NTIS (6847)

R&T Report Center, HRTS-03
Federal Highway Administration
9701 Philadelphia Court, Unit Q
Lanham, MD 20706
Telephone: 301-577-0818
Fax: 301-577-1421

For more information on research and technology publications from FHWA, visit the Turner-Fairbank Highway Research Center's (TFHRC) Web site at www.tfhrc.gov, FHWA's Web site at www.fhwa.dot.gov, the National Transportation Library's Web site at http://ntl.bts.gov, or the OneDOT information network at http://dotlibrary.dot.gov.

Laboratory Evaluation of Waterborne Coatings on Steel
Publication No. FHWA-RD-03-032

Researchers evaluated 10 commercial waterborne coatings formulated to protect new steel (SSPC-SP 10) from corrosion. They included five acrylic coatings, four epoxy coatings, and one polyurethane coating. The volatile organic compound content of all the coating materials was below 300 grams per liter (2.5 pounds per gallon). Researchers determined several key chemical and physical properties to investigate their effects on coating performance. In general, the binder-to-pigment weight ratio stayed above 1.0 for acrylic primers but remained below 1.0 for epoxy primers. The researchers developed a rapid infrared spectroscopic technique to distinguish styrene-modified acrylics from unmodified (vinyl) acrylics. The performance evaluation involved both laboratory and outdoor tests.

The performance of the waterborne acrylic formulations currently in use has been improved significantly, and the results are competitive with the best performing, solvent-borne acrylic and epoxy barrier coatings. Properly formulated two-coat acrylic and epoxy systems can perform as well as generally similar three-coat systems with different formulations. The analysis of the test results showed strong discrimination against zinc-rich systems by test A but not by test B. The cyclic freeze/UV-condensation/salt fog-dry air test that used 5 percent sodium chloride solution to generate salt fog produced a coating performance similar to that in a salt-rich environment including zinc-rich and waterborne coatings.

Assessment of Selected LTPP Material Data Tables And Development of Representative Test Tables
Publication No. FHWA-RD-02-001

This report documents an evaluation of selected data tables of Long-Term Pavement Performance (LTPP) material as of January 2000. Issues addressed include the availability, characteristics, and quality of the data in the selected tables. Anomalies in the data were identified and corrected where possible, and the cleaned-out data were used in developing representative data tables. Recommendations for adjustments in the current process for data collection also are presented.

Validation of the Superpave™ Asphalt Binder Fatigue Cracking Parameter Using an Accelerated Loading Facility
Publication No. FHWA-RD-01-093

An Accelerated Loading Facility (ALF) was used to validate the Superpave asphalt binder parameter for fatigue cracking, G*sin(delta). The ALF is a full-scale machine for pavement testing that applies one-half of a single, rear truck axle load. The speed of the ALF and the applied load were constant in this study.

Two unmodified asphalt binders were used. These binders had Superpave performance grades of 58-34 and 64-22 and continuous intermediate-temperature performance grades of 9 and 17, respectively. Both asphalt binders were from the same crude source. A single aggregate gradation and a single asphalt binder content were used. Two layer thicknesses of asphalt pavement were tested: 100 and 200 millimeters (4 and 8 inches). Each pavement was tested at three temperatures: 28, 19, and 10 degrees Celsius (82, 66, and 50 degrees Fahrenheit). A total of 12 pavement sites (two binders at two thicknesses and three temperatures) were tested.

The pavements failed sooner at the middle test temperature of 19 °C (66 °F) for a given asphalt binder and pavement layer thickness. Neither the strain-control parameter, G*sin(delta), nor the stress-control parameter, G*/sin(delta), alone can explain the effect of temperature. As expected, each 100-mm (4-inch)-thick pavement failed sooner than the 200-mm (8-inch)-thick pavement layer with the same asphalt binder and pavement test temperature.

Only one of the six comparisons used to evaluate the effect of binder grade on fatigue-cracking performance showed that the mode of loading was strain control, which is the mode of loading used by the Superpave asphalt binder specification. Four of six comparisons indicated that the mode of loading was stress control, although the stress-control parameter, G*/sin(delta), could not explain the effect of test temperature on fatigue-cracking performance. The sixth comparison was inconclusive with regard to the applicable mode of loading.

The pavement data indicated that the mode of loading can change with temperature. For the 100-mm (4-inch)-thick pavements, the mode changed from strain to stress control with a change in temperature from 28 to 19 °C (82 to 66 °F). Fatigue cracks in all pavements started at the bottom of the asphalt pavement layer.

HERS-ST: Highway Economic Requirements System—State Version; Pilot Program Report 2002
Publication No. FHWA-IF-02-056

The primary purpose of this report is to summarize the findings of the Highway Economic Requirements System—State Version (HERS-ST) Pilot Program and discuss the steps taken to create the first version of HERS-ST intended for national distribution. The pilot program included white papers commissioned by FHWA, prototype software suitable for testing, and a workshop that provided training, opportunities for peer exchange, and ongoing technical support.

Overall, the report is intended to satisfy the following key objectives: (1) document the comments regarding the usefulness of HERS-ST to State departments of transportation; (2) catalog, discuss, and assess comments and recommendations for HERS-ST improvements received from the participants; (3) assist readers in understanding the background and development of HERS-ST, how it works, and how it is being used at the Federal and State levels; (4) describe the expectations of current, new, and future users of HERS-ST; (5) outline FHWA's approach in developing HERS-ST software for broad release; and (6) present recently completed and future HERS-ST activities.

September/October 2003

Communication Product Updates Compiled by Zac Ellis of FHWA's Office of Research and Technology Services

Communication Product Updates
Compiled by Zac Ellis of FHWA's Office of Research and Technology Services