Flexible Pavement Evaluation and Overlay Design

A rational method for flexible pavement evaluation and overlay design using the Dynaflect deflections is presented. Evaluation charts and design curves are based primarily on the results of a comprehensive two-year study during which the Dynaflect deflections were systematically monitored on selected flexible pavements located strategically throughout Kansas. Various factors, including the pavement thickness, volume of traffic, subgrade soil type, temperature and average rainfall are taken into consideration. The adequacy of the sample size of the deflection measurements is tested statistically throughout the study. A pavement evaluation scheme consisting of a visual condition survey and a structural diagnosis chart based on the Dynaflect measurements is presented. The data from the study are used to develop temperature adjustment factors and seasonal adjustment factors. Charts are presented whereby representative values of DMD and SCI can be used to compute the thickness of the overlay required for the pavement to sustain the design traffic. The implementation of the developed subsystem in a pavement management system is illustrated by a flow chart.