Suggested Citation: Theyse, H., Fenella Long, David Jones, John T. Harvey (2006) Full-Depth Pavement Reclamation with Foamed Asphalt: First-Level Analysis Report on HVS Testing on State Route 89. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-06-25
This report focuses on the HVS testing of a foamed asphalt treated, reclaimed asphalt pavement (RAP) on State Route 89 near Sierraville. The report discusses the expected behavior of the HVS test sections, presents the results from field surveys done during June 2003, October 2003 and May 2004 as well as the 1st level analysis of HVS results from the test site. Results from field surveys done prior to, during and after HVS testing show that the pavement structure of the HVS test sections on SR89 is not representative of the mainline and foamed asphalt treated, reclaimed asphalt concrete in general. The mode of distress of the test sections differs between the favorable conditions in summer and fall and unfavorable conditions in winter. The mode of distress before the onset of winter consisted of gradual deformation of the pavement resulting in a terminal surface rut with limited fatigue cracking. After the winter, the mode changed to a more rapid rate of rutting and on Sections 595FD and 596FD tested during spring, shear failure of the base layer occurred in certain locations. These sections also showed extensive fatigue cracking. The pavement structure of the HVS test section showed sensitivity to high moisture contents in terms of elastic and plastic response. The resilient modulus of the base layer decreased during the winter and spring and the rut rate increased. Although not to the same extent, a reduction in base layer resilient modulus on the mainline was also observed from FWD results. It is recommended that FWD surveys should be done in each of the four seasons of the year to track changes in pavement condition. If the reduction in base layer resilient modulus is permanent, it may lead to early fatigue of the asphalt surfacing layer. The pavement bearing capacity only exceeded the design value under favorable conditions in the fall and early winter. The pavement structure of the HVS test sections is, however, not representative of the mainline pavement structure and therefore not representative of the bearing capacity of foamed asphalt treated, reclaimed asphalt pavements. The bearing capacity of the pavement is subject to seasonal effects and cannot be estimated from a single HVS test result. It is recommended that a seasonal simulation should be done using the results from the HVS tests in each season and seasonal traffic data in a second level analysis of the HVS data.