Development of a Rational and Practical Mix Design System for Full Depth Reclaimed (FDR) Mixes

This report presents the findings of a research study carried out for the development of a rational and practical mix design system for Full Depth Reclaimed (FDR) mixes. This research project involved selecting project locations, obtaining samples from selected FDR sections, and detailed laboratory testing for evaluation. Planned work involved determination of effect of moisture content, compactive effort and additive content on volumetric and mechanical properties of FDR mixes. The overall work plan consisted of selection of test sections, sampling of materials from test sections, development of a mix design method using the Superpave gyratory compactor, construction of test section, evaluation of in-place materials, refinement of mix design and testing of in-place materials after construction of test sections. Work also included development of a rapid design procedure using the gyratory compactor only, and determination of resilient modulus of subgrade soils. The criteria used for determination of optimum total fluid content are based on the determination of dry density and resilient modulus. Adequate resistance to moisture damage is a significant factor in obtaining good performance from stabilized base course mixes, and departments of transportation (DOTs) should consider any good test that they are comfortable with, to evaluate resistance of designed FDR mixes to moisture damage. Three different types of tests methods have been discussed. Based on the research conducted in this study, it is concluded that the Superpave gyratory compactor can be used successfully for compacting full depth reclamation mixes. Use of a slotted mold is recommended to allow squeezing out of water during compaction of full depth reclamation mixes. Use of samples in sealed bags is recommended for determination of bulk specific gravity in the laboratory. A dry density versus total fluid content criteria can be used to determine the optimum total fluid content. If an asphalt emulsion is used, then the total fluid consists of preexisting water in the material plus the emulsion. Any one of the additives considered in this study improves resistance of FDR against moisture damage. Cement and emulsion plus lime mixes show very high resistance to moisture damage compared to the other mixes. However, on the basis of wet tensile strength, emulsion plus lime is better than any other additive considered in this study. Therefore, use of emulsion and lime, and cement in low percentage, for full depth reclamation of materials similar to the materials studied in this project is recommended. FDR samples for mix design should be compacted to 50 gyrations during mix design, and a minimum of 95% of density of in-place loose mix samples, compacted to 50 gyration, is recommended to be achieved in a control strip in the field. Compaction in actual project must achieve at least 98% of the control strip density. Increase in structural numbers for FDR layers should be considered for designing binder and surface layers.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Figures; Photos; References; Tables;
  • Pagination: 103p

Subject/Index Terms

Filing Info

  • Accession Number: 01531748
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 18 2014 2:12PM