Specialized Testing of Asphalt Cements from Various ADOT&PF Paving Projects

Abstract

The Alaska Department of Transportation and Public Facilities (ADOT&PF) sampled five different asphalt cements for specialized testing at Queen’s University in Kingston, Ontario. This report documents and discusses the findings. The tested asphalts were: PG 58-34, PG 52-40D, PG 52-40N, PG 58-28, and PG 64-28. Testing results showed that grade losses according to Ontario’s LS-308 Extended Bending Beam Rheometer (EBBR) ranged from 3.4°C to 6.3°C. Losses according to Ontario’s LS-228 Modified Pressure Aging Vessel (PAV) ranged from 0°C to 7.3°C. Grade losses of 3°C and higher are significant in terms of their ability to reduce pavement life cycles. Double-edge-notched tension (DENT) tests according to Ontario’s LS-299 DENT protocol were done on PAV residues. The critical crack tip opening displacement (CTOD) was determined and, at 15°C, it varied from a low of 19 mm for the PG 58-28 to a high of 175 mm for the PG 58-34. The PG 58- 40D showed a CTOD of 139 mm, contrasting with the low polymer PG 52-40N at only 36 mm, a nearly four-fold difference. All the results obtained from this specialized testing effort suggest that these materials will provide significant differences in performance. This report provides recommendations on how to obtain better value for money by implementing a few simple changes to the ADOT&PF asphalt cement specifications.