An Evaluation of Superpave Binder Aging Methods

Abstract

The objective of this study is to evaluate the rolling thin film oven (RTFO), and the pressure aging vessel (PAV) binder aging methods recommended by superpave. Test sections for this study were set up in 1992 and 1993 using six highways in five states: US 280 and AL 86 in Alabama, I-90 in Idaho, I-40 in New Mexico, I-385 in South Carolina, and STH 67 in Wisconsin. Asphalt binder was recovered from loose mix obtained during construction and from cores obtained after first, second and third year. Dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests were conducted on the recovered binder and on asphalt binders subjected to RTFO test (RTFOT) and PAV method. Comparison of DSR test results of asphalt binder recovered from loose mix and DSR test results of RTFOT conditioned asphalt binder indicated that asphalt binders are aged more in the plant mix process than in the RTFOT process. However, statistical analyses indicate that the RTFOT method seems to be capable of simulating short term aging of asphalt binder. Complex shear modules (G*) and phase angle (δ) values from asphalt binder extracted from in-place mixes were used to develop time versus property models. G* values were found to increase and δ values were found to decrease with time. Low temperature stiffness (S) values from asphalt binder extracted from in-place mixes were used to develop S versus time models. Stiffness values were found to increase with time. G*, δ, and S values after 10 years were predicted on the basis of the G*, δ, and S versus time models. The predicted fatigue factor (G*sin δ) and S values were then compared to G*sin δ and S values obtained from tests on laboratory aged asphalt binders. The comparison indicated that the PAV method is capable of simulating long term aging of asphalt binders.

Keywords:

• Binder
• Aging
• Superpave
• Fatigue factor

Notes

^†Tel.: [phone]. Fax: [phone]. Email: [email protected]

Additional information

Notes on contributors

E.R. Brown †

†Tel.: [phone]. Fax: [phone]. Email: [email protected]