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https://nap.nationalacademies.org/catalog/27432/critical-issues-in-transportation-for-2024-and-beyond

Spray Applied Polymer Surface Seals: Lessons Learned Workbook

This study addresses the problem of asphalt cement hardening in pavements and was undertaken to determine the effects of spray applied surface seals on the long-term performance of asphalt pavements. This study was designed to evaluate the effectiveness of this preventive maintenance strategy. Traditionally, these treatments, often called fog or flush seals, are applied to pavements to arrest pitting and raveling, to reduce shrinkage tendencies, to decrease permeability, to decrease traffic and snow plow damage, and to rejuvenate the properties of the existing asphalt cement. These treatments are also used to improve appearance. Different types of sealers and rejuvenators are available in the marketplace. Sealers such as SS-1 (Slow Setting emulsified asphalt) or CSS-1 (Cationic Slow Setting emulsified asphalt) are commonly used to “seal” the pavement surface or to “bind” or “lock” cover material or fines in place reducing surface attrition. Rejuvenators, on the other hand, are designed to penetrate into the existing age-hardened asphalt cement, thereby modifying and improving existing chemical and rheological properties. The product selection is dependent upon the problem being solved and the existing pavement type. The most prevalent use of rejuvenator products is on dense graded asphalt surfaces. Sealer products, on the other hand, are more commonly applied on chip seals and friction courses where binding or enrichment is the main purpose. Both product types have been used successfully on all three surface types. To better understand the process of embrittlement in flexible pavements, it should be remembered that the oxidation of asphalt occurs during both the construction phase and during the service life of the pavement. Asphalt hardening during the construction operation can be predicted, to a large degree, by laboratory aging procedures. Hence, the initial rheology of the binder can be adjusted to account for typical changes expected during hot mix asphalt (HMA) mixing and compaction. The long-term aging of asphalt during the in-service pavement life is much more difficult to control. It is closely linked to the asphalt’s crude source, the environment, and interconnected air voids near the surface through which oxygen and moisture can infiltrate. Sealers and rejuvenators are used in a preventive maintenance strategy to prevent surface asphalt from reaching the limiting stiffness where surface cracks begin to appear. This study was initiated to determine the effectiveness of seals and evaluate the effects and possible mitigation efforts on safety. This project has four main tasks: collecting existing information; placement of several experimental sections within different climates, traffic levels and surface characteristics; evaluation of field and laboratory test methods and data collected from the test sections; and disseminating the lessons learned.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; CD-ROM; Figures; Photos; References; Tables;
  • Pagination: 372p

Subject/Index Terms

Filing Info

  • Accession Number: 01525545
  • Record Type: Publication
  • Contract Numbers: DTFH61-01-X-00004
  • Files: TRIS, ATRI, USDOT
  • Created Date: May 28 2014 3:21PM