Application of intermediate temperature semi-circular bending test results to design mixtures with improved load-associated cracking resistance

Abstract

This paper describes the development and practical application of regression equations to estimate the relative load-associated cracking resistance of asphalt mixtures from properties that are included in specifications and controlled through current quality control and acceptance procedures. This work was part of a research study performed through the Wisconsin Highway Research Program to evaluate changes to the composition of asphalt concrete mixtures that should be considered to improve the durability of flexible pavements. Based on the findings of a synthesis of current research, a laboratory experiment was conducted to quantify the effect of (1) effective binder volume, (2) virgin binder low temperature performance grade, (3) recycled binder content, and (4) polymer modification on the resistance of typical Wisconsin mixtures to ageing and load-associated cracking. For the types of mixtures normally used in Wisconsin, the laboratory experiment found mixture composition had little effect on ageing; however, load-associated cracking resistance was significantly affected. The laboratory experiment produced a regression equation that was used to recommend revised volumetric criteria that provide equivalent load-associated cracking resistance and allow producers the flexibility to design mixtures using a range of effective binder contents, recycled binder contents, and virgin binders.

Keywords:

• load-associated cracking
• semi-circular bend
• flexibility index
• age hardening

Acknowledgements

The contents of this paper reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views of the Wisconsin Department of Transportation or the Federal Highway Administration at the time of publication.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This paper is based on research that was funded through the Wisconsin Highway Research Program by the Wisconsin Department of Transportation and the Federal Highway Administration under Project 0092-14-06.