Bitumen stress relaxation modulus and its slope as performance-based criteria to control low temperature cracking

ABSTRACT

This paper aims to determine the performance-based criteria for bitumen to control low temperature cracking in asphalt pavements. For this purpose, the performance of 26 recovered bitumen samples was analysed using the dynamic shear rheometer with 4-mm parallel plates (4-mm DSR). The stress relaxation modulus and its slope at 60 s were determined by performing a stress relaxation test at specific critical temperatures. The changes in these properties depending on the test temperature were analysed. The stress relaxation modulus and its slope at 60 s of 26 recovered bitumen samples were compared with the actual performance of the road sections from which these bitumen samples were recovered. On the basis of that, the limiting values of the stress relaxation modulus and its slope at 60 s were determined. The research showed that the formation and development of low temperature cracks on asphalt pavements are limited, when the stress relaxation modulus and its slope at 60 s and at temperature 10°C higher than the lowest asphalt surface temperature are not higher than 52 MPa and not lower than 0.370, respectively. These performance-based criteria are incorporated into the algorithm developed to assess bitumen resistance to low temperature cracking.

KEYWORDS:

• Low temperature cracking
• bitumen
• 4-mm DSR
• relaxation modulus and its slope
• performance-based criteria

Disclosure statement

No potential conflict of interest was reported by the author(s).