Evaluation of Canadian Asphalt Overlay Roughness Using C-SHRP and LTPP Data

摘要

This paper studies asphalt pavement overlay performance in Canada. It investigates the impact of asphalt overlay thickness, climatic zone, and subgrade type on the progression of roughness as described by the International Roughness Index (IRI). Data from the Canadian Long Term Pavement Performance Test Sites (C-LTPP) was analyzed. It was shown that pavement factors significantly impact overlay performance in the Canadian environment. The first 13 years of data was used to show national and provincial roughness trends from 53 test sites. The IRI data was statistically summarized for each category by the age of the overlay section. Using the summarized data, regression analysis was used to determine an equation that best describes the progression of roughness. Two-factor analysis of variance was used to determine significant differences within specific categories. The roughness progression equations were compared to the Canadian Strategic Highway Research Project LTPP to confirm their validity. Results show that overlay thickness and climatic zones significantly impact roughness, while subgrade type has little influence on IRI values. The roughness progression equations achieved squared correlation coefficients between 0.93 and 0.60. Finally, the impact of overlays on the overall life cycle cost of the pavements was analyzed.