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theses

Protecting our asphalt pavements structures from possible distresses such as pavement cracking and pavement rutting require good understanding of materials used to construct pavement structures. When conducting QA/QC or a forensic analysis to characterize asphalt materials that were used on existing roads and highways requires extensive number of cores to be taken per section. The coring process will initiate cracks in the coring location, which will propagate later on and may lead to the formation of alligator cracks and potholes. Many of the currently utilized test apparatus utilize a minimum of a 6-inches core to provide a sample large enough to test. Sample preparation after coring is limited further by lift thickness; to not test a composite material one must cut the field core sample to ensure only one pavement lift is being tested. If the pavement design specifies a lift that is less than the minimum size for current test apparatus, no testing can be completed on that sample. Incorporating recycled asphalt materials and shingles in mixture designs makes it even more challenging to characterize combined asphalt mixture properties. The combination of virgin and recycled asphalt requires the development and implementation of material testing methods that can test asphalt mixtures in the solid form. Labs that are interested in studying the impact of aging, time, and temperature on the commingling of RAP and/or shingle asphalt on the stiffness modulus of bituminous mixtures find it difficult to use current asphalt mixture performance tests. This is due to different reasons such as time-consuming performance testing process, samples size, and test/analysis complexity. In this research, a new methodology was developed to simplify and expedite forensic testing. The developed methodology addressed previously mentioned asphalt mixture performance testing issues. The developed methodology consists of two main tools. A new test procedure using the Sliver Test ASTM D7552. A forward and backward models based on the modified Hirsch model developed by, Christensen et al, currently being used in the pavement design guide. The developed methodology successfully analyzed asphalt mixture and asphalt binder response parameters from the sliver test output. Developed methodology successfully helped forward calculate asphalt mixture complex modulus and backward calculate asphalt binder complex modulus avoiding asphalt binder chemical extraction process. The methodology was developed using 700 data points then verified using a total 1050 data points. Statistical goodness of fit parameters and coefficient of variance was performed. Results showed promise and the methodology was able to forward calculate asphalt mixture (R^2>95.5%) and asphalt binder complex modulus (R^2>87%).

ETD_8784

Ph.D.

Includes bibliographical references

by Mohamed Monir Haggag

doi:10.7282/T3474F9P

ETD doctoral

The author owns the copyright to this work.