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The measured strain during a creep-recovery (CR) test comprises both reversible and irreversible strains; therefore, adequate treatment is required to accurately separate them. In this paper, a generalised version of the CR test was proposed to investigate the permanent deformation behaviour of asphalt mixtures exerted by a variety of loading patterns in the time domain. The companion back-calculation algorithm was also proposed to separate with improved accuracy and repeatability the pure viscoelastic (VE) and viscoplastic (VP) strains. First, the creep compliance (CC) was back-calculated based only on the recovery data by using an approximate analytical creep compliance function of the Huet-Sayegh model as the solution function in the optimisation process. Then, the pure VE and VP strains were determined. The results show that the proposed method attains a good level of reliability although relatively short durations of the recovery period have been used. [ABSTRACT FROM AUTHOR]

The use of un-conventional materials in asphalt pavements is becoming popular as DOTs in many countries started to legislate their in the paving industry. The motive behind this is to get rid of available waste while maintaining or improving the pavement performance Fly ash is among those recycled materials that can be used as a substitute for virgin aggregates inbituminous mixtures. This study investigates the effect of using Municipal Solid Waste Incineration Fly Ash (MSWI-FA) as partial or full replacement of fine aggregates and mineral filler on the performance of asphalt mixtures.. The purpose of the experimental testing program is to determine the optimal MSWI-FA replacement type and percentage to be used in asphalt mixtures. This is done through a series of dynamic modulus tests with different MSWI-FA replacement percentages. The different mixes are then ranked based on their rutting and fatigue cracking potential using simple performance indicators. [ABSTRACT FROM AUTHOR]

The high-resolution X-ray CT was applied to investigate the fatigue damage evolution of asphalt mixtures. The detailed Xray CT images in the centre of the samples were used to characterise the fatigue cracking and air voids increase at different vertical deformations. Air void content and surface area distribution before and after loading were also analysed. The results show that the main failure mode of asphalt mixtures at low temperature is debonding at the interface between aggregates and mastic, which is an adhesive failure. The maximum change of air void content due to fatigue damage often occurs near the middle of the sample. Cracks were observed in and around flat and elongated aggregates and on aggregates with insufficient fracture faces, demonstrating the effects of aggregate angularity and shape on fatigue cracking. The microcracks develop continuously throughout the entire fatigue process. [ABSTRACT FROM AUTHOR]