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Report Details

Title:Field Performance of Asphalt Mixtures Based on Flexibility Index Results
Authors:Pedro Romero
University:University of Utah
Publication Date:Jul 2022
Report #:MPC-22-466
Project #:MPC-611
TRID #:01855176
Keywords:asphalt mixtures, fatigue cracking, flexibility, mechanical tests, pavement performance


This document presents the continuous effort to develop mechanical tests that can relate to the expected performance of asphalt mixtures once placed in the field. During a previous research project, asphalt mixtures of different compositions were collected from different locations across the state of Utah. Based on the tests, it was found that asphalt mixtures sampled at the plant had a flexibility index (FI) between 3.0 and 20.0. This means that some mixtures were likely to show premature fatigue cracking.

To verify if the laboratory predicted performance matched the field performance, the locations where five different mixtures were placed were surveyed and their level of distresses was documented.

It was found that out of the five sections surveyed, the one that had the lowest flexibility index showed premature fatigue cracking. A different section also shows significant low-temperature cracking.

Based on the results, it is concluded that the proposed mechanical testing at intermediate temperatures can be used to identify mixtures that might have poor cracking performance in the field. However, since no other section showed any distresses, it is not known if a specific minimum FI can be developed at this time.

How to Cite

Romero, Pedro. Field Performance of Asphalt Mixtures Based on Flexibility Index Results, MPC-22-466. North Dakota State University - Upper Great Plains Transportation Institute, Fargo: Mountain-Plains Consortium, 2022.

NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050