DYNAMIC DEFLECTIONS OF PAVEMENT: MEASUREMENTS, INTERPRETATIONS AND APPLICATIONS

Recent emphasis by highway agencies on pavement management system makes it almost imperative to monitor the in-service behavior of pavements periodically and systematically. Pavement deflection measurements are increasingly being used as a part of this state-wide monitoring system. Equipment like dynaflect, road rater and wes vibrator are used for dynamic deflection measurements, among which dynaflect is the most used one in the United States. Five performance parameters - dmd, sci, bci, sp and w5 are associated with the dynaflect measurements. The physical significance of each of these parameters is described. A structural diagnosis chart utilizing all the parameters is presented to estimate the structural characteristics of the measured pavement system. A nomograph is presented to check the adequacy of sample size of pavement deflections at 95 percent confidence level. Significance of temperature adjustment factor and seasonal adjustment factor is enumerated. Design charts to determine overlay thickness of flexible pavements based on dmd and sci crtieria are presented. Application of dynaflect deflections in the evaluation of hot and cold recycled pavements is also discussed. (Author/TRRL)