Region 4 of the Oregon Department of Transportation (ODOT) beganthe use of cold in-place recycling (CIR) for rehabilitation of asphalt pavements in 1984. The process has proven successful and today is an important part of ODOT's surface preservation strategies. ODOT, with assistance from Oregon State University, has actively monitored selected CIR projects constructed between 1984 and 1988. Detailed data are presented for 10 projects with regard to visual inspection, deflection data before and after recycling, diametral resilient modulus and fatigue, and Marshall stability and flow. A tabulation of service life estimates for 47 CIR projects and the life cycle cost implications thereof are also presented. Most of the CIR projects haveonly been chip sealed. In several cases cold, open-graded overlays have been applied. Significant findings include the followin (a) deflections before and after CIR are about the same, and no structural improvement should be expected; (b) generally, for CIR projects over time, diametral modulus and fatigue life and Marshall stability increase while Marshall flow decreases; and (c) with the exception oftwo significant failures, life cycle costs for CIR projects ranged from 37 to 82 percent of the cost of a 2-in hot mix overlay.
Samenvatting