Characterizing the Precision Uncertainty in Vibratory Roller Measurement Values

Understanding precision uncertainty in roller measurement values (MV) from continuous compaction control and intelligent compaction vibratory soil and asphalt rollers is required for implementation of roller-based specifications for pavement construction quality control/quality assurance (QC/QA). Accordingly, MV uncertainty can have a significant influence on the acceptance criteria specified in QC/QA. Two pertinent uncertainties are examined within this context: (1) uncertainty in single roller MV data and (2) uncertainty in the difference between roller MVs at the same location from consecutive passes. The uncertainties were estimated from roller MV records using two experimental methods: (1) evaluation of consecutive pass MV records and (2) determination of a nugget variance from geostatistical variogram analysis of a single pass of MV data. The nugget method was found to be dependent on the reporting characteristics of the MV data. A procedure that uses uncertainty analysis to determine malfunctioning roller measurement systems and MVs insensitive to soil properties was demonstrated. The uncertainties from different MVs were found to be similar when evaluated on the same soil. However, MV uncertainty was found to vary between different soils using the same roller. The uncertainty estimated in this study has significant implications on acceptance criteria and nature of QC/QA specification.