Correlation of Laboratory and Field Friction Measurements to Optimize Utilization of Bituminous Surface Aggregates

The primary objectives of this research project are to: (1) Perform laboratory polish value (PV) testing of surfacing aggregates and validate the BPN and PV correlation developed by the Texas Department of Transportation (TxDOT) and Indiana Department of Transportation (INDOT). (2) Perform race-track locked-wheel skid testing and develop/validate the correlation between field BPN and locked-wheel Friction Number (FN). Selection of the pavement sections will consider the variations in geography and associated climatic conditions. (3) Monitor and evaluate the effects of cumulative traffic on BPN and FN measurements and develop skid life predication model. (4) Develop a correlation between laboratory PV and field FN. (5) Develop recommendations for selecting and prequalifying surfacing aggregates to meet the pavement friction demand and allowing optimal utilization of bituminous aggregates. Major tasks include: 1) Identify eight existing pavement sections, two (2) in Region 2 and six (6) in Region 4, of known surfacing aggregate sources which have a history of consistency in production and mineralogical compositions. Utah Department of Transportation (UDOT) and researcher to secure aggregate samples from these sources and researcher will perform laboratory testing for PV and BPN and compare PV results produced from the current standard to that of the project records. 2) For the 8 selected pavement sections identified in 1) above – (a) asses the cumulative vehicle passes per lane (VPPL) data from traffic map and pavement age, (b) UDOT and researcher to identify surfaces representative of the aggregate quality and perform race-track skid (FN) testing, (c) researcher to perform BPN testing within the same skid paths, (d) perform FN and BPN testing in two cycles in a year to represent Spring thaw and Fall pavement conditions. 3) Select 4 new pavement sections, two (2) in Region 2 and two (2) in Region 4, in the preconstruction phase – (a) researcher perform laboratory PV testing of submitted aggregate sources, (b) research team establish 2 to 3 comparisons between the standard and single-sized seal coat aggregate gradations, and (c) research team develop skid history (FN) correlation with cumulative VPPL. 4) Research team will develop a MOI for UDOT personnel to use during field testing of FN and BPN. The MOI will include the procedures for collecting FN and BPN data. 5) Using proper statistical technique, research team will evaluate the results of the laboratory PV and field FN values, and develop a correlation between the two. 6) Safety Meeting prior to field work to discuss UDOT provided Traffic Control during field BPN testing.