Influences of Binder and RAP Temperatures and Foaming Water Content on Cold In-Place Recycling Mix Design Process Using Foamed Asphalt

Abstract

The Cold-In-Place Recycling using foamed asphalt (CIR-foam) is becoming more common in rehabilitating the existing asphalt pavements due to its cost effectiveness, the conservation of paving materials, and its environmental friendliness. The main objective of this research is to identify the influences of binder and RAP temperatures and foamed water content on the wet indirect tensile strength. Although the optimum foaming water content and temperature can be found through the experiment which would produce the highest expansion ratio and longest half-life, it may not necessarily produce the optimum foamed asphalt mixture. Therefore, these asphalt foam design parameters such as foaming water content and binder temperature were considered as part of the foamed asphalt mix design process which is to determine the optimum foamed asphalt content for varying RAP temperatures. Based on the limited test data collected from Johnson County in Iowa, RAP temperature was found to have a significant impact on the wet indirect tensile strength whereas either foamed asphalt temperature of foaming water content did not significantly affect the wet indirect tensile strength. It is recommended that the amount of foamed asphalt content should be adjusted depending on the existing pavement temperature during CIR construction.