Application of high viscosity-high modulus modified asphalt concrete in bus rapid transit station pavement–A case study in Chengdu, China

The pavement of bus rapid transit (BRT) stations is subjected to highly channelized load caused by buses, which can cause serious distresses and may lead to early failure. For asphalt pavements, rutting is the most common distress under such conditions. In this study, a case study of the latest BRT paving project in Chengdu, China was introduced. Two asphalt mixtures were designed to serve as the station pavement surface. PG 76-22 asphalt was modified with high viscosity and high modulus addictive to further improve its mechanical properties. The effects of the modification were validated by a series of Hamburg wheel tracking tests. The test results suggested that gap-graded mix performed better in rutting resistance than dense-graded specimens. Modification with high viscosity agents could significantly inhibit rutting propagation. If the mix was modified with both high viscosity and high modulus agents, it would be able to avoid stripping under the most severe test condition. As for project implementation, a life cycle cost analysis was carried out to compare different paving plans. The construction process of BRT pavement was elaborated with detailed description and photos, explaining base treatment, paving, compaction, and quality control, which could help guide the construction of future BRT paving projects.