COMPARISONS OF FIELD AND LABORATORY ESTIMATED RESILIENT MODULI OF PAVEMENT MATERIALS (WITH DISCUSSION)

The Washington State Department of Transportation (WSDOT) entered into a cooperative agreement with the University of Washington to develop a new overlay design procedure. The following tasks are being pursued: (1) Develop an overall concept for the design procedure; (2) Conduct a performance study of in-service pavements using WSDOT pavement evaluation records; (3) Develop a means of characterizing in-situ material properties for flexible pavements using the WSDOT falling weight deflectometer (FWD); (4) Characterize traffic on a statewide basis using data provided from weigh stations; and (5) Adapt an elastic analysis procedure for estimating pavement response and for determining the required overlay thickness. This paper discusses the effort to develop a means of estimating the elastic properties of pavement materials from FWD deflections, describes the test sections on which the method was tried, presents comparisons between the field and laboratory estimates of resilient moduli, and discusses the differences between the two methods.