Vibratory Compaction of Asphalt Concrete.

摘要

Over the last few years,the New York State Department of Transportation has investigated the feasibility of using vibratory compaction on asphalt concrete. A total of 10different roller models were used on 10contracts--3overlays and 7new construction. The rollers represented a wide range of dimensional and operating characteristics,which initially led to a wide variation in results. However,discovery of two important operating parameters resulted in development of performance criteria applicable to any roller. These parameters--the spacing of drum impacts and their magnitude--can be controlled by adjusting forward speed,drum frequency,and drum amplitude. Impact magnitude,termed Unit Total Applied Force (UTAF),was correlated with layer thickness to produce the ranges necessary for each lift. As would be expected,the force necessary for adequate compaction increased with lift thickness,but on lifts thinner than 3in.,the maximum force applied was found to be equally critical. If too great,roller rebound occurred,reducing densities. Vibratory rollers also compacted single-lift wearing and base courses--respectively 2 1/2and up to 8in.--more efficiently than conventional rolling. In sum,vibratory rollers when operated properly were found to be effective in compacting asphalt concrete. Also,rather than accept or reject rollers individually,operating criteria were developed to determine the ability of any roller to compact a given lift thickness.