Presented herein is a discussion of a new nondestructive device that will measure density continuously while hot asphaltic concrete is being compacted by the contractor. Density on the run consists of a nuclear source and detectors mounted inside a rotating drum, 6 5/8 in. In diameter by 18 inch long. It is placed directly on a steel wheel roller compactor so that density can be reported instantly to the operator, density that may change (intentionally or unintentionally) because of changes in ballast, rolling speed, frequency, and amplitude of vibration and temperature. This device can be removed fromthe roller in minutes and mounted on a two-wheeled cart to measure and optimize density performance of the asphalt paver. It can also be used to take stationary readings and provide moisture data for base course construction. Density on the run may be used to (a) deal with shortcomings of nuclear and conventional coring specifications in which one test in 1,200 lane-ft is often considered adequate agency acceptance; (b) reduce rolling hours and optimize asphaltic concrete paver performance to avoid penalties and solve problem variables of compaction; (c) measure density of large areas, furnishing the added data to statistically analyze uniformity of density and its relationship to quality in flexible pavements; (d) offset the shortcomings of stationary nuclear density meters; and (e) implement high-speednuclear testing and pneumatic roller compaction testing and measure the density of thin lift overlays as small as 3/4 in. in 1-in. increments.
Abstract