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This thesis discusses and documents the validation efforts related to Ontario’s LS-299 and LS-308 test methods which are two new test methods developed for the performance-based specification grading of asphalt cement. In addition, this report presents the field validation of a simple performance indicator, loss tangent, for specification grading of asphalt cement for thermal cracking. Furthermore, another objective of this study is to investigate and compare the low temperature fracture and rheological behavior of engineered asphalt materials from field and laboratory-aged test sections on Highway 655 in northern Ontario. Extracted asphalt cements from 20 contract sites in eastern and northeastern Ontario were tested according to Ontario’s LS-299 and LS-308 test methods. It was found that all good performing contracts that showed little or no distress showed low grade losses in LS-308 and retained high strain tolerances as measured in LS-299 compared to the poor performing contracts. Asphalt cements recovered from these 20 contract sites in eastern and northeastern Ontario were also tested in torsion bar geometry to determine their viscoelastic properties. It was decided to focus on the phase angle, as a more direct measure for low temperature performance. Phase angle is a very sensitive parameter to small changes in rheology as the phase angle is approximately equal to the derivative of the logarithm of the stiffness with respect to frequency. It was found that tan() was able to distinguish good from poor performers with 95% accuracy after only a short period of conditioning prior to testing. This is a considerable improvement over the current low temperature bending beam rheometer protocol. Black space diagrams, frequency sweeps, Cole-Cole plots, and master curves were generated for comparison of field and laboratory aged materials from the Highway 655 trial in northern Ontario. The findings show that chemical hardening occurs much faster in the field than through laboratory ageing methods. Also, reversible ageing of binders may occur at low temperatures and could be linked to field performance. Furthermore, a high low temperature phase angle appears to be a reasonable indicator for thermal cracking resistance. / Thesis (Master, Chemistry) -- Queen's University, 2009-08-28 15:12:29.845

This thesis deals with nonlinear analysis of reinforced concrete structures under monotonically increasing loads. Post-cracking behaviour of planar reinforced concrete structures is studied to investigate the tension stiffening phenomenon and the post-cracking shear resistance. The feasibility of using the available bond stress-slip relationships to model the steel-concrete interface behaviour is examined by incorporating these relationships in a three dimensional axisymmetric finite element model and analyzing several reinforced concrete tension specimens. / A finite element model which uses the advanced endochronic stress-strain relationship and incorporates the results of the investigation on post-cracking behaviour and steel-concrete interface behaviour is formulated and used in the analysis of several reinforced concrete members. Analysis results are compared with the available experimental data and with the results obtained by other researchers. Excellent correlation was obtained between the computed values and the experimental results.

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