EVALUATION OF A 15-YEAR ASPHALT PAVEMENT FOR HOT-IN-PLACE RECYCLING

Hot-in-Place recycling was used on an experimental basis along the Provincial Highway System in Alberta from 1989-93. Since then, until 1999, 2 other projects were undertaken. In 1999, Alberta Infrastructure decided to use the hot-in-place recycling approach on a few projects for its Year 2000 rehabilitation program. One of these was a 20 km stretch of primary highway 2:58 and 2:60 located in the Peace Region of the Province of Alberta, approximately 500 km north west of the City of Edmonton. While this highway was identified for the treatment, the mandate was to first determine its suitability for the proposed treatment. This assessment involved undertaking field and lab testing of the existing asphalt concrete pavement from core samples taken at 19 locations approximately 1 km apart. A total of 57 cores were taken with 3 cores at each sampling location to obtain sufficient samples to undertake various characterization tests. Lab tests included core density, asphalt content, absolute viscosity, penetration, and gradation of the extracted aggregate. Test results were compared with features of the mixes and aggregate at the time of construction of the highway and with data from the 1989-93 investigations. The data evaluation yielded interesting information regarding characteristics of the asphalt cement, consistency in the production of the mix, and pavement compaction at the time of construction and 15 years later, as well as air voids and asphalt content characteristics. Based on test results, the physical condition of the pavement, and the structural soundness of the pavement, it was decided that rehabilitation by hot-in-place recycling would be beneficial and cost effective.