RELATIONSHIPS OF AASHO ROAD TEST PAVEMENT-PERFORMANCE OF DESIGN AND LOAD FACTORS.

Abstract

A SAMPLE IS PRESENTED OF THE PAVEMENT PERFORMANCE DATA AT THE AASHO ROAD TEST AND AN EXPLANATION OF HOW THE DATA WERE SUMMARIZED BY MEANS OF EMPIRICAL EQUATIONS FOR FLEXIBLE AND RIGID PAVEMENT PERFORMANCE. PRESENT SERVICEABILITY AND HISTORIES FOR EACH TEST SECTION WERE PLOTTED AGAINST LOAD APPLICATIONS, THEN SMOOTHED INTO SERVICEABILITY TRENDS BY USE OF MOVING AVERAGES. THE GENERAL FORMULAS ARE PRESENTED FOR FLEXIBLE PAVEMENT SERVICEABILITY TRENDS AND FOR PERFORMANCE OF RIGID PAVEMENT. ALL OF THE POWERS AND COEFFICIENTS IN THE FLEXIBLE AND RIGID PERFORMANCE EQUATIONS WERE DETERMINED THROUGH REGRESSION ANALYSIS OF THE FACTORIAL EXPERIMENT DATA. CRITERIA USED FOR THE SELECTION OF EQUATIONS TO EXPRESS SERVICEABILITY TRENDS: (1) MODELS WERE PREFERRED WHOSE AVERAGE LOG W RESIDUALS WERE SMALLER, (2) MODELS WERE PREFERRED THAT WERE RELATIVELY LESS COMLICATED IN ALGEBRAIC FORM, AND (3) MODELS WERE PREFERED WHOSE EXTRAPOLATED CHARACTERISTICS SEEMED TO AGREE BEST WITH PAST EXPERIENCE AND PRESENT EXPECTATIONS. TERMINAL SERVICEABILITY IS FIXED AT A PARTICULAR VALUE IN PERFORMANCE EQUATIONS. GRAPHS OF RELATIONSHIPS AMONG DESIGN, LOAD AND APPLICATIONS ARE PRESENTED. THE FIRST ROAD TEST OBJECTIVE WAS TO DETERMINE THE EFFECTS OF PARTICULAR PAVEMENT DESIGN AND AXLE LOAD FACTORS ON PAVEMENT PERFORMANCE. IT IS CONSIDERED THAT OF THE CURVES SHOWN AND OTHER CURVES THAT CAN BE COMPUTED FROM THESE PERFORMANCE EQUATIONS SATISFY THE MAIN OBJECTIVES FOR THE FACTORIAL EXPERIMENTS.