Density measurement verification for hot mixed asphalt concrete pavement construction

Oregon Department of Transportation (ODOT) requires a minimum density for the construction of dense-graded hot mix asphalt concrete (HMAC) pavements to ensure the likelihood that the pavement will not experience distresses that reduce the expected service life of the pavement. Currently, the ODOT Standard Specifications call for density measurements for both quality control and quality assurance testing to be made using nuclear density gauges that are calibrated using reference blocks. Hence, acceptance (i.e., purchase) of the HMAC pavement (or portions thereof) relies on the accuracy of the measurements. However, it has been observed that density measurement results using nuclear gauges have been questionable on a number of projects and that repeatability and reproducibility with the same gauge and between gauges have also been unattainable. Further, these observations have called into question the confidence placed in the use of nuclear gauges for determining HMAC pavement density.  The overall objective of the project was to recommend a system that accurately quantifies density of dense-graded HMAC pavements. This involved critically evaluating how ODOT currently measures HMAC density, investigating and evaluating what other agencies do to measure HMAC density, and conducting testing and analysis of alternate ways of measuring HMAC density (e.g., by measuring the density of cores).  Statistical analyses comparing nuclear gauge measurements to core densities provided convincing evidence that correlation of nuclear gauge measurements to core densities is necessary to ensure accurate results from nuclear gauges. Analyses comparing correlation factors across lifts of pavements constructed under three differing construction scenarios provided strong evidence to suggest correlation factors established for one lift can be used on other lifts under certain constraints. Correlations are recommended for all gauges on each lift and whenever a new mix design is introduced. ODOT should implement use of the CoreLok device for measuring densities of pavement cores and laboratory-prepared specimens as well as further investigate the use of electromagnetic gauges for in-place HMAC density measurement, This archived document is maintained by the Oregon State Library as part of the Oregon Documents Depository Program.  It is for informational purposes and may not be suitable for legal purposes., OrDocs shipping list 2010-20, Title from PDF title page, "June 2010.", Includes bibliographical references (p. 157-161), Performed by Oregon State University, Kiewit Center for Infrastructure and Transportation under contract no. SPR 666, Mode of access: Internet from the Oregon Government Publications Collection., Final report
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This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.
Abstract/Description: Oregon Department of Transportation (ODOT) requires a minimum density for the construction of dense-graded hot mix asphalt concrete (HMAC) pavements to ensure the likelihood that the pavement will not experience distresses that reduce the expected service life of the pavement. Currently, the ODOT Standard Specifications call for density measurements for both quality control and quality assurance testing to be made using nuclear density gauges that are calibrated using reference blocks. Hence, acceptance (i.e., purchase) of the HMAC pavement (or portions thereof) relies on the accuracy of the measurements. However, it has been observed that density measurement results using nuclear gauges have been questionable on a number of projects and that repeatability and reproducibility with the same gauge and between gauges have also been unattainable. Further, these observations have called into question the confidence placed in the use of nuclear gauges for determining HMAC pavement density. The overall objective of the project was to recommend a system that accurately quantifies density of dense-graded HMAC pavements. This involved critically evaluating how ODOT currently measures HMAC density, investigating and evaluating what other agencies do to measure HMAC density, and conducting testing and analysis of alternate ways of measuring HMAC density (e.g., by measuring the density of cores). Statistical analyses comparing nuclear gauge measurements to core densities provided convincing evidence that correlation of nuclear gauge measurements to core densities is necessary to ensure accurate results from nuclear gauges. Analyses comparing correlation factors across lifts of pavements constructed under three differing construction scenarios provided strong evidence to suggest correlation factors established for one lift can be used on other lifts under certain constraints. Correlations are recommended for all gauges on each lift and whenever a new mix design is introduced. ODOT should implement use of the CoreLok device for measuring densities of pavement cores and laboratory-prepared specimens as well as further investigate the use of electromagnetic gauges for in-place HMAC density measurement
Subject(s): n-us-or
Asphalt concrete -- Density -- Measurement
Pavements, Asphalt concrete -- Oregon -- Design and construction
Hot mix paving mixtures
Date Issued: [2010]