Evaluation of Cement-Stabilized Full-Depth-Recycled Base Materials for Frost and Early Traffic Conditions

A primary goal of this research was to characterize the properties of cement-treated base (CTB) materials constructed from reclaimed asphalt pavement (RAP) and aggregates obtained from several locations in New England. Extensive laboratory testing was performed to evaluate the strength and durability of the materials in the untreated condition and after treatment with various levels of cement. Testing included determinations of particle-size distributions, moisture-density relationships, unconfined compressive strength (UCS) values, and moisture susceptibility classifications for the materials. The results of the laboratory testing were used to establish design parameters for field test sections constructed in the summer of 2005. Field testing was conducted to characterize the structural properties of both cement-treated and untreated full-depth recycling (FDR) base materials subjected to early trafficking. One of the field test sites was also monitored during the 2005-2006 winter and spring to examine variations in performance-related properties that result from seasonal changes in temperature and moisture content. In addition to conducting the laboratory and field testing, the scope of this project included evaluation of six mechanistic-empirical models for predicting fatigue of CTB layers. Knowledge of the fatigue life of CTB layers is useful to pavement engineers during the design process, especially in situations in which the base layer will be expected to bridge over weak subgrades. For example, during spring in cold regions, frost-susceptible subgrade soils may exhibit severe thaw weakening and markedly reduced bearing capacities. In this situation, the decreased support beneath the CTB layers permits the occurrence of greater horizontal tensile stress in the CTB layer at its interface with the subgrade. Depending on the magnitude of the induced tensile stress relative to the tensile strength of the CTB material, bottom-up cracking may occur, deteriorating the pavement integrity. Based upon the available numerical models, charts were developed to predict expected pavement life associated with varying asphalt concrete and CTB thicknesses and varying CTB and subgrade modulus values. This report describes the laboratory and field testing that was conducted, as well as the numerical modeling regarding the fatigue life of CTB layers. The research findings and design recommendations are summarized in the conclusion, and suggested specifications for construction of cement-treated FDR base layers are included in Appendix B.

Language

  • English

Media Info

  • Media Type: Digital/other
  • Edition: Final Report
  • Features: Appendices; Figures; References; Tables;
  • Pagination: 107p

Subject/Index Terms

Filing Info

  • Accession Number: 01531742
  • Record Type: Publication
  • Files: TRIS, ATRI, USDOT
  • Created Date: Jul 18 2014 1:19PM