Implementation of the Double-Edge-Notched Tension Test for Asphalt Cement Acceptance

Abstract

This paper focuses on an investigation of the implementation of the double-edge-notched tension protocol (DENT, Ministry of Transportation of Ontario LS-299 and American Association of State and Highway Transportation Officials TP 113-15) for the acceptance of asphalt cement. Since 2012, the DENT test has been implemented with associated criteria for the acceptance of modified binders used in provincial and municipal paving contracts. A total of 21 binders from different contracts were collected for this study and tested according to the LS-299 DENT protocol to determine essential and plastic works of failure (we and βwp, measures of strength and toughness), and an approximate critical crack tip opening displacement (CTOD, a measure of strain tolerance). It was found that nearly all samples were able to reach the CTOD as specified in the contract but that a significant number contained recycled engine oil bottoms, with anticipated long term durability and moisture sensitivity problems. Polymer contents were inconsistent across different grades and performance differences between tank and recovered binders were found to be considerable and unpredictable. Hence, it is imperative that, at an early opportunity, recovered binders are tested to assure minimum performance criteria are being met in terms of CTOD as well as we and βwp, and that a ban be implemented on the use of deleterious additives. The implementation of the DENT test will allow user agencies to reduce detrimental fatigue cracking distress in thin asphalt pavements.