February 2000

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Feature

A Professional Society for Pavement Coatings

by Girish C. Dubey

The Pavement Coating Technology Center is a valuable resource for those interested in advancing knowledge about the pavement coating industry. PCTC chairman Girish Dubey describes the organization’s purpose and goals, as well as its involvement in ASTM standards activities.

Introduction

The Pavement Coating Technology Center (PCTC) is a technology center for the advancement of the pavement coating industry and various entities that use pavement coatings. It was established in 1992 as a joint enterprise of industry and the University of Nevada, Reno. The center is housed in the Department of Civil Engineering, with full access to all research and testing facilities at the Engineering Laboratory Center at the Reno campus. The PCTC is operated by Dr. Peter Sebaaly as its director, under the guidance and assistance of the executive and other committees, comprising the members of PCTC. The center is funded through the dues from various membership classes.

The mission of the center is to provide opportunities for dialogue, education, advancement, and improvement of all aspects of the pavement coating industry through research and development, training, seminars, communications, publications, meetings and various other programs.

Background

Pavement coatings, also called sealcoatings, are used for the protection and preservation of asphalt surfaces from ultraviolet degradation, water, salts, chemicals, etc. Sealcoatings are mostly used on off-street pavements, e.g., parking lots, driveways, low-to-medium traffic bearing roads, airports, etc.

Sealcoatings were introduced in the late 1940s and have evolved through the years, primarily through the individual efforts of manufacturers and raw material suppliers, with very little communication, especially on their technical aspects. The applicable specifications of sealcoatings, in effect as late as the late 1980s, were primarily qualitative in nature, with minimal requirements on their performance criterion.

The lack of technical unification within the industry prompted the Federal Aviation Administration (FAA) to address the performance specification issues on its own and it undertook the task of developing technical specifications for the use of sealcoatings at airports. Over the years, FAA has funded several projects at the University of Nevada, Reno, to develop performance-driven specifications that resulted in Engineering Brief No. 46, addressing the qualitative and performance requirements of sealcoatings based on refined coal tar in January 1990. This was the beginning of the dialogue between the industry and various agencies, which resulted in the establishment of the PCTC.

Goals

The center’s scientific goal is to provide the sealcoating industry with guidelines and standards both for materials and application methods, a strategy that has worked well for the pavement construction industry. The sealcoating industry must be assured through meaningful tests and application standards to accomplish consistent performance.

Even though the FAA support for several research activities has resulted in noticeable advances in the area of mix design of sealcoatings, the industry, in general, has acknowledged that it still lags behind in crucial areas, e.g., standardized test methods, unified application specifications, etc. The PCTC has addressed each of these aspects and is steadily moving towards technical unification through its various programs. PCTC has outlined the following tasks as goals:

1. Refinement and development of performance-based specifications;
2. Round-robin testing;
3. Training courses for sealcoating professionals and authorities specifying the use of sealcoatings;
4. Research and development;
5. Literature Center.

Current Activities and Accomplishments

The PCTC has been aggressively addressing all the issues related to sealcoatings—technical, environmental, safety, and the like—with noteworthy accomplishments to date. Some major accomplishments are:

ASTM Test Methods—The PCTC recently completed a report summarizing the findings of a research project on the development of test standards for durability of coal tar sealer using the mechanical scrub test, WTAT (wet track abrasion test), field fuel resistance test, and freeze/thaw cracking tests. The report presents the data produced during the development of these tests and summarizes the recommended test procedures in a form ready to implement as an ASTM standardized test method.

The PCTC actively reviews all types of proposed ASTM and FAA standards, relating to sealcoatings and other surface treatments. It has recently concluded the review of FAA item P-629 on sealer/rejuvenators. The specification for asphalt emulsion-based sealers is under review and recommendations will be made to ASTM Committee D-8 on Roofing, Waterproofing, and Bituminous Materials for further action.

Research Projects—The PCTC is currently working on a major project to identify the performance characteristics of refined coal tar emulsion-based sealcoatings and the impact of various ingredients on its overall longevity. All major components—refined coal tar, clay, and additives—will be studied for long-term performance through laboratory simulations.

Additionally, the PCTC is studying the field application of test sections applied in Reno and Kansas City, to determine the effects of sand loading, age of the asphalt pavement, inclusion of additives, etc., on the performance of sealcoatings.

The PCTC will also study the applicability of the tests (developed for refined coal tar emulsion sealers) to asphalt emulsion-based sealers.

Training Courses—The center will develop training courses for professionals involved in all relevant aspects of sealcoating projects—selection, testing, application and inspection. The center will offer the courses on an annual basis with instructors from academia, industry, the FAA, airports and other public sector authorities. Currently it is in the process of developing a one-day credit course for architects and sealcoating specifiers, covering the principles of pavement maintenance, cost/benefits analysis, and field performance data.

Literature Center—A technical library has been set up at the University of Nevada, Reno. The center is continually updating the database, containing important information on pavement coatings, for use by manufacturers, applicators, and specifiers of sealcoatings.

The center’s progress has been noteworthy in the past years and hopefully, it will continue to grow in the future with the support of its membership of suppliers, manufacturers, contractors, and governmental and public agencies. For membership, contact Dr. Peter Sebaaly (775/784-6565; fax: 775/784-1429). //

Talk to the Editor: Maryann Gorman

by Girish C. Dubey

Girish C. Dubey is the present chair of the PCTC. He has been actively associated with the pavement maintenance and
coatings industry for over 28 years and has published several technical papers. Dubey is the president of S.T.A.R., Inc., Columbus, Ohio.