Short-Term Field Performance and Cost-Effectiveness of Crumb-Rubber Modified Asphalt Emulsion in Chip Seal Applications

Abstract

Chip sealing is a commonly used pavement maintenance technique that aims to delay pavement deterioration by reducing water infiltration and restoring skid resistance. The objective of this study was to evaluate the short-term field performance and cost-effectiveness of chip seals prepared with different types of asphalt emulsion and application rates. A newly introduced crumb-rubber modified asphalt emulsion was evaluated, one that allows chip seal installation at the same temperature as a standard emulsion. Types of emulsion included a crumb-rubber modified asphalt emulsion (CRS-2TR), a polymer-modified emulsion (CRS-2P), and a conventional unmodified emulsion (CRS-2). Application rates were obtained from the Louisiana Department of Transportation and Development (DOTD), the Texas Department of Transportation (DOT) specifications, and from the chip seal design method recommended in NCHRP Report 680. Seven chip seal sections were constructed and monitored regularly over a 12-month period. In the northbound lane, the chip seal section constructed with CRS-2TR (0.37 gal per square yard [gsy]) was the best performer statistically. In the southbound lane, the chip seal sections constructed with CRS-2TR and CRS-2P (0.31 gsy) performed similarly. Furthermore, the maximum Service Life Extension (SLE) was observed for the CRS-2TR (0.31 gsy) chip seal sections, whereas the chip seal sections constructed with CRS-2 had the lowest SLE. In addition, the most cost-effective chip seal section was achieved by the application of CRS-2TR emulsion at the Louisiana DOTD recommended emulsion application rate.