Effects of compaction on the initiation and propogation of top-down cracks and the shear properties of asphalt mixes

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The research work of the applicant over the past 20 years has established that one major cause of the early deterioration of asphalt pavements is construction-induced cracks.  This conclusion was proved when a fundamentally new compaction device, Asphalt Multi-Integrated Roller (AMIR), was developed.  The AMIR compactor prevents such cracking during construction.  A second primary cause of early deterioration is shoving of the asphalt mix as a result of insufficient shear stiffness under traffic loading.  In another ground-breaking effort, the applicant developed a new equipment, In-Situ Shear Stiffness Test (InSiSST).  This facility measures the shear properties of asphalt pavements "on-the-road" without the need for the time consuming, costly, and unrepresentative laboratory analysis.   The proposed research builds upon these two important achievements.  The research plan consists of four main tasks: (1) experimental investigation including field and laboratory testing from test sections in Canada and overseas, (2) theoretical investigation, (3) development of prediction models based on the results of the preceding investigations, and (4) evaluation of short and long-term performance.  The research plan includes the construction of field tests using the AMIR and steel rollers (side by side), and field and laboratory tests to compare their long- term performance.  In addition, a theoretical investigation will be carried out to develop statistical models for predicting pavement behaviour and performance based on reliable field and laboratory data.  The modeling of pavement performance will continue to evolve over the five-year duration of the project.  The most significant impact of the proposed work is the development of a Canadian technology dealing with a universal market that is an important component of the nation's infrastructure.  The proposed research is expected to improve pavement performance, compaction, and evaluation technologies.