The National Academies

NCHRP 20-50(14) [Completed]

LTPP Data Analysis: Significance of "As-Constructed" AC Air Voids to Pavement Performance

  Project Data
Funds: $100,000
Research Agency: Applied Pavement Technology, Inc.
Principal Investigator: Stephen Seeds
Effective Date: 6/5/2000
Completion Date: 6/28/2002

Many highway agencies use air voids or other volumetric properties (e.g., voids in mineral aggregate and asphalt content) as payment attributes in QC/QA specifications for hot mix asphalt (HMA). These agencies have developed statistical tolerances for air voids from historical data and set specification levels for air voids based on experience. However, quantifying relationships between air voids and HMA pavement performance has proven more difficult.

The objectives of this project were to (1) evaluate the use of LTPP data for determining the effect of in-place air voids and other mix volumetric properties on the performance of HMA pavements, (2) develop new or modified air voids content guidelines for optimum pavement performance, and (3) examine the effect of the level of construction control in the LTPP GPS and SPS on the variability of as-constructed air voids and other volumetric properties. Accomplishment of these objectives was seriously hampered by a lack of suitable data in the LTPP database.

NCHRP Research Results Digest 269, based on the agency's final report, summarizes key findings from the project. The full final report is available here.

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