Comparison of Full-Depth Reclamation with Portland Cement and Full-Depth Reclamation with No Stabilizer in Accelerated Loading Test

Abstract

Full-depth reclamation (FDR) with or without various stabilizers has been successfully used as a rehabilitation strategy in California since 2001. Long-term field monitoring on several FDR projects that used foamed asphalt with portland cement as the stabilizer combined with a comprehensive laboratory study resulted in the preparation of guidelines and specification language for this rehabilitation strategy in 2008. However, the design criteria were essentially empirical, in line with California design procedures for a rehabilitation project of this level. Recently, interest has grown in the use of cement, engineered emulsion, and no-stabilizer FDR strategies in addition to foamed asphalt and in the use of mechanistic design in a greater range of rehabilitation projects. Consequently, the research initiative was extended to a second phase including accelerated load testing on an instrumented test track constructed with these four FDR strategies to gather data for developing performance models that could be included in mechanistic–empirical rehabilitation design procedures. This paper summarizes results of the second set of tests in this accelerated loading study, which compared no-stabilizer and portland cement strategies. The portland cement stabilized section outperformed the unstabilized section in all measured aspects. The most notable observation was in relation to rutting performance; the unstabilized section reached a terminal rut depth of 13 mm after approximately 490,000 equivalent standard axle loads were applied, compared with the cement section, which had a rut depth of only 3.0 mm after more than 43.3 million equivalent standard axle loads. No cracking was observed on either section at the end of testing. Advantages of using portland cement over unstabilized pulverized material are clearly evident from the results.