Abstract

The purpose of this research was to determine the effect of full-depth reclamation (FDR) on the strength and durability of aggregate base layers in a coordinated approach involving both field and laboratory testing. Field comparisons between the pre-reclamation neat base and post-reclamation blended base were supplemented with laboratory experiments conducted to determine the effects of reclaimed asphalt pavement (RAP) content, compaction effort, and heating on the strength and durability of roadways reconstructed using FDR with a portable asphalt recycling machine (PARM). Also, the effect of reclamation on the spatial uniformity of the pavement structures was explored by comparing variability in the pre- and post-reclamation material properties. Test sites in Orem, Utah; San Marcos, Texas; and South Jordan, Utah, were selected for this research. The results of field testing indicate that the FDR process significantly increased the stiffness and/or strength of the base material at two of the test locations and did not significantly change the third base material. An evaluation of spatial variability indicated that the FDR process produced equivalent or lower spatial variability with respect to both base modulus and California bearing ratio (CBR) values at one site, while the other two sites exhibited equivalent or higher spatial variability after FDR. The results of laboratory testing for all three locations indicate that specimens compacted using the modified Proctor method exhibit significantly higher CBR values and dry densities than specimens compacted using the standard Proctor method. Also, the CBR values for specimens tested in the dry condition were significantly higher than those obtained from specimens tested at optimum moisture content. These results demonstrate the value of achieving a high level of compaction during construction and preventing water ingress into the pavement over time. The blended material exhibited a significantly lower CBR value than that of the neat material at only one location; the addition of RAP to materials at the other locations did not significantly change the CBR values of those materials. In the tube suction test (TST), most of the specimens were classified as marginally or highly moisture-susceptible, and the effect of RAP on the dielectric value in the TST was of no practical importance. The use of PARMs in the FDR process is an acceptable, economical, and environmentally friendly approach to reconstruction of flexible pavements. To ensure satisfactory performance of FDR projects, engineers and managers should carefully follow recommended guidelines for project selection, pavement testing, material characterization, design, construction, and quality assurance testing.

Degree

College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering

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