The National Academies

NCHRP 09-30 [Completed]

Experimental Plan for Calibration and Validation of HMA Performance Models for Mix and Structural Design

  Project Data
Funds: $200,000
Research Agency: Fugro Consultants LLP
Principal Investigator: Harold Von Quintus
Effective Date: 10/15/2001
Completion Date: 2/28/2004

The accuracy of performance prediction models depends on an effective process of calibration and subsequent validation with independent data sets. Pavement engineers need to see an acceptable correlation between field-observed levels of permanent deformation, fatigue cracking, and low-temperature cracking and levels predicted with the hot-mix asphalt (HMA) performance models selected for use in structural and mix design.

NCHRP Project 1-37A, "Development of the 2002 Guide for the Design of New and Rehabilitated Pavement Structures: Phase II," identified state-of-the-practice performance models and supporting test methods for use in the recommended Mechanistic-Empirical Pavement Design Guide and Software. Present plans call for adapting these same performance models to the requirements of the Superpave mix design and analysis method due for completion in 2005. Using this method, the engineer will arrive at a final HMA mix design by considering structural, traffic, and environmental factors in addition to material properties, thus fulfilling the original goal of the 1993 SHRP mix design and analysis method.

In Project 1-37A, an analytical approach was used for the calibration and validation of the HMA models; the calibration and validation are based on material properties either contained already in the LTPP database or derived from LTPP data by calculation. NCHRP Project 9-30 developed an experimental plan to refine this calibration and validation using material properties measured with the requisite test methods on laboratory-prepared HMA specimens or field cores where necessary.

The objective of this research was to develop a detailed, statistically sound, and practical experimental plan to refine the calibration and validation of the performance models incorporated in the proposed 2002 design guide with laboratory-measured hot mix asphalt (HMA) material properties for future use in mix and structural design methods.

The findings of the research are summarized in NCHRP Research Results Digests 283, Jackknife Testing: An Experimental Approach to Refine Model Calibration and Validation, available online at
http://trb.org/publications/nchrp/nchrp_rrd_283.pdf, and 284, Refining the Calibration and Validation of Hot Mix Asphalt Performance Models: An Experimental Plan and Database, available online at http://trb.org/publications/nchrp/nchrp_rrd_284.pdf.

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