Development of Improved Pavement Rehabilitation Procedures Based on FWD Backcalculation

015609012015Final ReportPDFTech ReportProject No. 094IY04DTRT07-G-005Hot mix paving mixturesOverlays (Pavements)Flexible pavementsRehabilitation (Maintenance)ThicknessNondestructive testsFalling weight deflectometersBackcalculationFatigue crackingRuttingResearch HubDesignHighwaysMaintenance and PreservationPavementsI22: Design of PavementsRailways and GuidewaysUnited StatesNEXTRANS Center (U.S.)Tutumluer, ErolSarker, PriyankaNEXTRANS Center (U.S.)United States. Dept. of Transportation. Research and Innovative Technology AdministrationUS Transportation CollectionHot Mix Asphalt (HMA) overlays are among the most effective maintenance and rehabilitation alternatives in improving the structural as well as functional performance of flexible pavements. HMA overlay design procedures can be based on: (1) engineering judgment, (2) pavement component analysis, (3) non-destructive testing (NDT) with limiting defection criteria, and (4) mechanistic-empirical analysis and design. Although different state highway agencies have different methodologies in designing HMA overlay thickness, design procedures are more or less following or modifying the 1993 AASHTO Pavement Design Guide procedure, which is an empirical based approach using the structural deficiency concept and generally listed in above categories 1 and 2. The lack of mechanical testing for evaluating the structural conditions of existing, in-service pavements often leads to unsafe and uneconomical practices as far as the rehabilitation of low volume roads is concerned. This research study presents a mechanistic-empirical (M-E) approach for overlay thickness designs of flexible pavements through a combination of NDT and pre-established pavement damage models. Structural conditions of a n umber of in-service pavement sections were tested in the field using a Falling Weight Deflectometer (FWD) test device. The required overlay thicknesses of the field pavement sections were then determined using two different methods currently used by local agencies, and the newly developed M-E Overlay Design method. The M-E Overlay Design Method mechanistically backcalculates pavement layer moduli and critical pavement responses due to FWD loading using advanced materials characterization and layered analysis solutions, and then compares them to threshold pavement responses for the fatigue cracking and rutting pavement damage criteria according to pre-established pavement damage algorithms