Design Methods for Base Stabilization of Paved Roads

Abstract

Stabilization is a peculiar function of geosynthetics where the geosynthetics limit the horizontal and vertical deformations of a soil mass by developing lateral confinement through friction and/or interlocking. The stabilization function is widely used for improving the performance of the base and/or subbase of paved and unpaved roads. When installed at the bottom or within a base and/or subbase course, geosynthetics for stabilization afford to (1) increase the service life and/or (2) decrease the required layer thickness. The GMA White Paper (Berg et al. in Geosynthetic reinforcement of the aggregate base/subbase courses of pavement structures; Geosynthetic Materials Association, Roseville, MN, USA, 2000) and AASHTO R50-09 suggest that the improvement to the pavement system provided by geosynthetic can be designed based on modified AASHTO Guide for Design of Pavement Structures (Guide for design of pavement structures; American Association of State Highway and Transportation Officials, Washington, DC, USA, 1993) method by using a traffic benefit ratio (TBR) or base course reduction (BCR), or layer coefficient ratio (LCR) approach. These three approaches may lead to different design for the same road section, applied traffic, and boundary conditions. The latest AASHTO 2008 guidelines call for mechanistic–empirical design of paved roads: Design methods for base stabilization according to AASHTO 2008 are still under development. The paper is aimed to present the four different approaches and to compare the design resulting from their application. The differences in theory and practical results are finally used to provide recommendations for the selection of the most suitable approach and for evaluating the reasons of potential discrepancies when designing with different methods.