BACKGROUND: Geosynthetics are available in a wide range of forms and materials and are used in many applications. Geosynthetics are often used by highway agencies in conjunction with unbound base layers (i.e., within the layer or as a subgrade/base interface layer) as a means for enhancing the performance of flexible and rigid pavements. Although a great deal of research has been performed on the properties of these materials and their use in pavement structures, limited research has dealt with the methodologies of quantifying their influence on pavement performance in a manner that would allow incorporation into the mechanistic-empirical pavement design and analysis procedures. The AASHTO Interim Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) developed under NCHRP Project 01-37A provides a methodology for the analysis and performance prediction of pavements. However, use of geosynthetics in pavement layers and their influence on distress models have not been addressed in the MEPDG. Procedures that quantify the influence of geosynthetics on pavement performance will help in determining the payoff obtained by using these materials and selecting the appropriate material for a specific application. Such information is not readily available. Therefore, research is needed to (1) evaluate those tests currently used for characterizing geosynthetics and, if necessary, identify new tests that relate to performance and (2) develop a methodology for quantifying the influence of geosynthetics on pavement performance for use in pavement design and analysis. This information can be incorporated into the MEPDG thus allowing a rational analysis and design procedure of flexible and rigid pavements in which geosynthetics are used in conjunction with unbound bases/subbases.
OBJECTIVE: The objective of this research was to develop a methodology for quantifying the influence of geosynthetics on pavement performance for use in pavement design and analysis that is consistent with the MEPDG framework to facilitate implementation. This research dealt with the use of geosynthetics in conjunction with unbound base/subbase layers (i.e., within the layer or as a subgrade/base interface layer) for flexible and rigid pavements.
STATUS: Research is complete; the final report is available as NCHRP Web-Only Document WOD 235, Quantifying the Influence of Geosynthetics on Pavement Performance.