Laboratory Study of Full-Depth Reclamation Mixes

Full-depth reclamation (FDR) is the technique of in-place recycling of the asphalt-bound layer of a pavement along with part of the underlying unbound layer to produce an improved base material. The objective was to develop a mix design system for FDR and evaluate the performance of designed reclaimed materials from the western part of Maine. Mixes were prepared in the laboratory, and samples were compacted with the Superpave^® gyratory compactor. The samples were then tested for bulk specific gravity and resilient modulus. Samples of mixes prepared with asphalt emulsion, water, emulsion plus lime, emulsion plus cement, and emulsion plus lime and cement were also tested for their resilient moduli at different cure times and for their shear strengths. Rut tests were also conducted with the samples under water to evaluate the stripping potentials of the different mixes. The test results showed that maximum density and resilient modulus criteria can be used to select the optimum additive content for water and asphalt emulsion mixes. Comparison of performance testing results showed that mixes with additives develop strength faster and show significantly higher shear strength and stripping resistance than mixes with water only. For the materials tested, addition of lime and cement with asphalt emulsion appears to increase the rate of gain in strength and, hence, to result in faster curing and to increase the shear strength as well as resistance against moisture damage. It is recommended that FDR sections with asphalt emulsion, lime, and cement be constructed and evaluated for in-place performance.