An integrated model to assess asphalt cement quality on low-temperature performance and life cycle cost

The performance of an asphalt pavement is strongly affected by the response of the asphalt cement in the mix formulation to the in-service condition. In Canada, one of the major obstacles to achieving long term pavement performance is low temperature cracking. The Strategic Highway Research Program (SHRP) Superpave methodology incorporates design requirement based on the low and high in-service temperatures. This research examines how existing practice can be incorporated into the requirements of the SHRP Superpave Performance Graded (PG) asphalts. As well, it examines how modified asphalts relate to the low temperature susceptibility criteria. The research involves the development of a framework for an integrated model which examines low temperature cracking and how it relates to pavement performance and life-cycle cost. The model was divided into four modules and focuses on asphalt pavements.; This analysis examines the McLeod Penetration Viscosity Number (PVN) as a low temperature susceptibility indicator. The results show that PVN is a fingerprint as it remains constant over time. PVN also relates to the SHRP Superpave Performance Graded (PG) asphalts. A decrease in the minimum temperature corresponding to the PG asphalt is consistent with an increase in the PVN. As well, the PVN shows variation within a crude source as would be expected and it shows PVN is constant regardless of the calculation method. For modified asphalts, PVN is related to the minimum Superpave PG temperature. Based on the analysis for a small number of samples, indications are that PVN does not remain constant with time for the modified asphalts.; The Canadian Airport Model and Hajek model is used to predict cracking on the C-LTPP and C-SHRP test sites. The analysis indicates that the Hajek model and Canadian Airport model show good correlation to the observed cracking. Using roughness as the measure of pavement performance, the performance of the pavement is predicted. Low temperature cracking is related to roughness in terms of Riding Comfort Index (RCI). This research recommends a probabilistic lifecycle cost procedure should be carried out. A lognormal distribution is determined to be the most appropriate distribution for pavement lift thickness. An extensive analysis of material costs is presented. (Abstract shortened by UMI.)...