Design and Instrumentation of the Structural Pavement Experiment at the NCAT Test Track

01000364621750262004PDFTech ReportNCAT Report 04-01Asphalt mixturesCondition surveysDeflection testsDeteriorationEmpirical methodsImplementationInstallationInstrumentationMaterialsMechanistic designMoisture contentPavement designPavement performancePolymersStrain (Mechanics)Structural number (Pavements)Surface course (Pavements)TemperatureTest tracksThicknessCompressive stressesunbound pavement layersDesignHighwaysMaintenance and PreservationMaterialsPavementsResearchI22: Design of Pavements,Railways and GuidewaysI23: Properties of Road SurfacesI31: Bituminous Binders and MaterialsUnited StatesNational Center for Asphalt Technology (U.S.)Timm, David H.Priest, Angela L.McEwen, Thomas V.National Center for Asphalt Technology (U.S.)Alabama. Dept. of TransportationIndiana. Dept. of TransportationUnited States. Federal Highway AdministrationUS Transportation CollectionThis report detailed the design and instrumentation of a structural experiment at the NCAT test track. The objectives of this experiment include: 1. Validating mechanistic pavement models for flexible pavements. 2. Developing transfer functions for typical asphalt mixtures and pavement crosssections used in Alabama. 3. Studying dynamic effects on pavement deterioration from a mechanistic viewpoint. 4. Evaluating the effect of thickness and polymer modification on structural performance. To accomplish these objectives, eight sections were built at the NCAT test track consisting primarily of three HMA thicknesses and modified versus unmodified binders. Additionally, two sections were devoted to having an SMA surface course and a rich bottom layer. Each of the test sections was instrumented with moisture, temperature, strain and pressure gauges to measure pavement responses under traffic and environmental loading. Sensor selection, calibration and basic operating principles were discussed. Additionally, details regarding the data acquisition systems were provided. The installation procedures were documented. While the asphalt strain gauge procedures were deemed effective (85% of strain gauge locations are functional), it is recommended that in future installations additional cable ties be added to the asphalt strain gauges. The procedures used for the earth pressure cells resulted in 100% survivability at the writing of this report. As planning begins for the 2006 research cycle, where there may be more sections devoted to instrumentation, the following recommendations are made: 1. Investigate high-speed wireless data collection and transmission. The current highspeed collection scheme requires personnel beside the track while trucks are operating. A safer mode of operation would not have personnel near the track. Also, it is likely that many more sections would require a high-speed datalogger for each section. A wireless system to collect and transmit these data would certainly facilitate data collection. 2. Continue to investigate gauge technology as many advances may be made in the coming two years that could greatly improve survivability and the ability to measure in situ pavement responses. 3. Conduct an external field experiment to investigate the effects of installation on pavement density. The results of this experiment could further guide installation efforts during the next research cycle.73