Evaluation and Identification of Cracking Susceptibility of Asphalt Binders and Mixtures by Incorporation of Effects of Aging on Performance

An important aspect which causes a significant effect on performance of asphalt materials is aging. With increase of aging, asphalt materials lose their relaxation capabilities and becomes more susceptible to cracking. Thus, an improved understanding of how aging impacts the cracking behavior of asphalt materials will allow for design of more reliable and durable asphalt pavements. In this study, different laboratory aging levels were performed to simulate different periods of pavement service life. Various performance tests (including Complex Modulus (E*), Simplified Viscoelastic Continuum Damage (S-VECD), Semi Circular Bending (SCB) and Disk Shaped Compact Tension (DCT) tests for asphalt mixtures; Frequency and Temperature Sweep test using a Dynamic Shear Rheometer (DSR) with 4mm plate and Linear Amplitude Sweep (LAS) test for asphalt binders) were conducted to evaluate the changes of material’s properties (including fundamental viscoelastic/rheological property, fatigue characterization, and fracture behavior) over time. The advanced Mechanistic-Empirical (ME) Models (FlexPAVE and IlliTC) were also employed to simulate the aging effects using the predicted fatigue and thermal cracking performance of asphalt mixtures in context of pavement structure, traffic and climatic conditions. The performance tests and simulation models provided a way to quantify the effects of aging on cracking behavior of asphalt materials and they can estimate the roles of various mixture variables on the cracking performance. Based on the testing and simulation results, this study also (1) developed new performance indices to evaluate the fatigue performance of asphalt binders with aging; (2) developed a rheological-based mixture aging model to evaluate cracking and aging susceptibility of asphalt mixtures over time; (3) provided insights on the relationships between binder and mixture cracking behaviors. This dissertation makes a contribution in improvement of the approaches for evaluation of cracking potential of asphalt pavements and allows for assessment of different mixtures at early stage of material selection and mixture design

The use of building simulation within an architectural practice

This paper documents the development and implementation and use of simulation within an architectural practice and reports how its use facilitates the practice's commitment to Sustainable Design