Description
In California, the asphalt rubber (AR) binder used in an asphalt rubber seal coat (ARSC), which is also known as AR chip seal, has typically been a field blended asphalt rubber binder (Type II), which consists of asphalt binder, asphalt modifier, and crumb
rubber modifier (scrap tire crumb rubber and high natural crumb rubber). In recent years, terminal blended rubberized asphalt binders including a minimum of 18% crumb rubber have been developed by the paving industry. One such product is called crumb rubber R18 modified binder (CRR18MB) that contained a minimum of 18% crumb rubber in asphalt binder and was blended at a refinery or terminal. The CRR18MB can be used with or without warm mix additive (WMA). Trials of these products have been mostly used as binders in hot mix asphalt (HMA). To explore their potential use in seal coats and expand the toolbox to include this pavement preservation strategy, California Department of Transportation (Caltrans) has taken the initiative to evaluate the use of various binder products in seal coat application.
This paper describes an initial performance study on a rubber modified asphalt seal coat pilot project constructed on state route (SR) 36 near Red Bluff in Tehama County of California. The project included multiple test sections using both AR (Type II) and CRR18MB with and without warm mix additives and fine 3/8 inch chips over existing asphalt concrete pavement. Within each test section, four Performance Evaluation Sections (PESs) were established for detailed performance monitoring and evaluation. These PESs are to
be monitored over multiple years to determine their performance. The primary purpose of this project is to compare the performance of the different rubberized asphalt products in a semi-mountainous environment with low temperatures and chain wear.
