Modern Concepts for Density Control: Phase III: Embankment Materials

During 1969, 1970 and 1971 density data were obtained on bituminous wearing courses that were being constructed on several Minnesota trunk highways. Data were collected and analyzed from randomly selected locations on five bituminous surfacing projects. A statistical analysis was also performed on results from eleven other bituminous projects and on laboratory test results. Variation was determined from these data by computing the mean and standard deviation to reveal existing variability in acceptable construction of bituminous wearing courses. The results were used to evaluate present specifications and to develop a new acceptance sampling plan. The plan is based on statistical concepts that will define the degree of acceptable variation upon which decisions can be made with an established degree of confidence. Proposed statistical specifications are presented.