Evaluation of environmental impact on perpetual and conventional pavement designs: A Canadian case study

The Ministry of Transportation of Ontario (MTO) constructed a test section in partnership with University of Waterloo, the Ontario Hot Mix Producers Association (OHMPA) and various other partners to evaluate the use of perpetual flexible pavement design on Highway 401. Samples from different asphalt mixes used in the construction of the test sections were structurally evaluated by implementing dynamic modulus testing on the construction year. The samples were then stored and subjected to all seasonal effects, environmental impacts and aging for a year. The same asphalt samples were used to evaluate the dynamic modulus of the asphalt mixes after being subjected to freeze-thaw cycles representing one Canadian winter. The dynamic modulus results showed strong statistical evidence that a significant deterioration in average |E*| results occurred in the SuperPave (SP) 12.5, SP 25 and SP 25 with Rich Bottom Mix (RBM). The deterioration mainly occurred at the results of dynamic modulus at low temperatures as -10°C and 4°C. However, the SP 19 mix showed weak statistical evidence of deterioration after one seasonal effect on the samples. The dynamic modulus results were used to evaluate the benefits obtained by adding 0.8% of additional binder to the regular SP 25 mix to develop the SP 25 RBM. The dynamic modulus results did not show statistical significant difference between average |E*| of the SP 25 and SP 25 RBM on the construction year. Moreover, the benefits of additional binder content showed up clearly after one season of freeze-thaw cycles. The results of the dynamic modulus testing after one year of conditioning showed statistical evidence that the strain developed in SP 25 RBM is less than that developed in SP 25, when both mixes are subjected to the same load and loading frequencies especially at -10°C and 4°C.