Document Type

Report

Publication Date

7-2016

Abstract

The design number of gyrations (Ndesign) introduced by the Strategic Highway Research Program (SHRP) and used in the Superior Performing Asphalt Pavement (Superpave) mix design method has been commonly used in flexible pavement design throughout the US since 1996. Ndesign, also known as the compaction effort, is used to simulate field compaction during construction and has been reported to produce air voids that are unable to reach ultimate pavement density within the initial 2 to 3 years post-construction, potentially having an adverse impact on long-term performance. Other state transportation agencies have conducted studies validating the Ndesign for their specific regions, which resulted in modifications of the gyration effort for the various traffic levels. Validating this relationship for Iowa asphalt mix designs will lead to better correlations between mix design target voids, field voids, and performance. A comprehensive analysis of current Ndesign levels investigated the current levels with existing mixes and pavements and developed initial asphalt mix design recommendations that identify an optimum Ndesign through the use of performance data tests.

Comments

For this and other reports, visit the InTrans project page at http://www.intrans.iastate.edu/research/projects/detail/?projectID=-1591479650

Report Number

IHRB Project TR-667; InTrans Project 14-492

Granting Agencies

Iowa Highway Research Board, Iowa Department of Transportation; Federal Highway Administration, U. S. Department of Transportation

Language

English

File Format

PDF

File Size

2.80 mb

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