The feasibility of using variable feedback control intelligent compaction to evaluate the properties of subgrade and granular pavement layers was investigated at US 14 in Minnesota. The study was comprised of proof testing strips using an Ammann vibratory smooth drum roller. The soil of the test strips was then evaluated with the various portable testing devices commonly used for quality control and acceptance. The research findings documented in this paper focused on: (1) relationships between intelligent compaction roller-measured soil stiffness and various in-situ measurement values, (2) performance of variable feedback control of amplitude and frequency, and (3) comparison of roller-measured stiffness with rut depth from test rolling. The study findings show that roller-measured stiffness can be empirically related to in-situ compaction measurements, but that the strength of correlation depends heavily on the range of values over which the measurements are taken. The intelligent compaction system also identified areas of unstable subgrade material similar to test rolling.
Samenvatting