The AASHTO Mechanistic-Empirical Pavement Design Guide (MEPDG) pavement performance models and the associated AASHTOWare® Pavement ME Design software are nationally calibrated using design inputs and distress data largely from the national Long-Term Pavement Performance (LTPP). Further calibration and validation studies are necessary for local highway agencies’ implementation by taking into acc...

The photodegradation behavior of a straight asphalt was investigated using a new method “photodegradation test of asphalt binder using pressed thin film samples”. Although the photodegradation caused by outdoor exposure is limited to the near surface, the results confirmed that the degree of degradation during 1 to 2 months is more severe than that by the pressure aging vessel (PAV) test, which...

A review of several past studies clearly shows the effect of reduced air voids on improved fatigue and rutting performance of asphalt mixtures, both in the laboratory and field. Depending on mix type and experiment (which included constant-stress bending beam fatigue testing and field results from WesTrack), fatigue performance improved between 8.2 and 43.8% with a 1% decrease in air voids. Lik...

16. Abstract Pavement structures are designed for a finite life, usually referred to as performance period. This performance period is typically between 20 to 25 years for flexible pavements and between 25 and 40 years for rigid pavements. After this period, the pavement is predicted to reach a terminal level in terms of several preset criteria. This performance period can be reached by designi...

Assumption of a linear elastic system under static loading is questionable for structural response analysis of pavement-subgrade systems under dynamic nondestructive testing and moving wheel loads, especially if a deteriorated pavement is under study. Presented are the results of a parametric study using the three-dimensional finite element ABAQUS code; it investigates the effects of pavement d...

Many agencies use the AASHTO Guide for Design of Pavement Structures to design their pavement systems. The limitation inherent in this method is the empirical nature of the decision process, which was derived from a road test conducted almost 45 years ago in Ottawa, Illinois. The newly released Mechanistic-Empirical Pavement Design Guide (MEPDG), based on NCHRP Study 1-37A, has adopted a mechan...

Pavement deflection data are often used to evaluate a pavement’s structural condition non-destructively. It is essential not only to evaluate the structural integrity of an existing pavement but also to have accurate information on pavement surface condition in order to establish a reasonable pavement rehabilitation design system. Pavement layers are characterized by their elastic moduli estima...

This project explored a new approach in detecting vehicles on a roadway by making a roadway section itself a traffic flow detector. Sections of a given roadway are paved with carbon-nanotube (CNT)/cement composites; the piezoresitive property of carbon nanotubes enables the composite to detect the traffic flow. Meanwhile, CNTs can also work as the reinforcement elements to improve the strength ...

Compacted unbound granular materials are extensively used as sub-layer in pavement design. Most pavement design guides assume that they are responsible for the degradation and deformation of the roads and railways that they support. Biaxial tests are usually employed to investigate the elasto-plastic response of these materials to cyclic loading. A particularly interesting question is whether a...