Evaluation of Nuclear Density Gauge to Perform QA/QC on a Base Material Containing RAP

In a recent Virginia Department of Transportation (VDOT) study, it was found that VDOT could use up to 30% recycled asphalt pavement (RAP) in a base aggregate layer. To implement the use of RAP materials in the base, an effective quality assurance/quality control (QA/QC) protocol is needed. Based on the study, a Light Weight Deflectometer (LWD) device was recommended to be used for QC/QA of RAP-aggregate base construction. Currently, VDOT does not use an LWD device for any of unbound layer construction control. So, it would require a major modification of VDOT practices and a significant resource allocation to implement use of an LWD for compaction control. As an alternative, the proposed study would evaluate a nuclear density gauge - the current VDOT practice for compaction control - to monitor the construction quality of a base course when up to 30% RAP is blended with base aggregate. Several state DOTs use nuclear density gauge for such construction. A test strip or a pit will be constructed with RAP-aggregate blend and compaction density will be measured using nuclear density gauge along with a verification measurement by the Sand Cone test. If successful, a QA/QC protocol using a nuclear density gauge will be developed for RAP-aggregate base construction.