01124407

Component

https://doi.org/10.3141/2126-05

http://scholar.google.com...Hesp&publication_year=2009

This paper documents and discusses the field validation of a simple performance indicator for specification grading of asphalt cement for thermal cracking. The loss tangent, tan(δ), as defined by the ratio of the viscous over elastic modulus, G″/G′, is able to provide a quantitative measure of the sol and gel nature of asphalt cement. As such, tan(δ) relates closely to how well a material is able to relax stress and is therefore investigated as a surrogate performance indicator for thermal cracking. Asphalt cements from 20 contract sites in Ontario, Canada, were tested in torsion bar geometry to determine their viscoelastic properties. The findings show that tan(δ) was able to distinguish good from poor performers for this set of materials with 95% accuracy, which is a considerable improvement over the current bending beam rheometer protocol. In addition to the use of tan(δ), it is suggested that a measure of the critical strain tolerance in the ductile state could be included to provide a significantly improved performance grading method. Most of the worst performing contracts were found to contain zinc. The presence of this element suggests that the use of waste engine oils in asphalt production is likely widespread, since zinc is a universal additive in engine oil and is never found in straight asphalt cement.

01147489

09-0890

English

pp 39-46

2009

Transportation Research Record: Journal of the Transportation Research Board

9780309142564

Print

Figures (5) ; Maps (1) ; References (33) ; Tables (3)

Asphalt cement; Field tests; Specifications; Thermal degradation; Viscoelasticity; Zinc

Performance indicators; Waste oils

Ontario (Canada)

Highways; Materials; I31: Bituminous Binders and Materials

TRIS, TRB, ATRI

Jan 30 2009 5:08PM

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• Virginia’s Higher Specification for Reclaimed Asphalt Pavement: Performance and Economic Evaluation