No abstract

No abstract

No abstract

No abstract

This paper presents research evaluating the effectiveness of rejuvenators for production of very high (40% to 100%) reclaimed asphalt pavement (RAP) content mixtures. Nine differently originated softening agents were tested; these included plant oils, waste-derived oils, engineered products, and traditional and nontraditional refinery base oils. Two different dosages of the agents were added to binder extracted from RAP to evaluate their softening potential through testing of kinematic viscosity and penetration at two different temperatures. At 25°C the softening efficiency varied by a factor of 12 between the most and least effective rejuvenators. Consistency results at different temperatures were used to express temperature susceptibility by means of penetration index (PI), penetration–viscosity number, and bitumen test data chart of the softened binders. The PI results varied measurably depending on the rejuvenator and supported the low-temperature mixture test results, showing that PI may be a good and simple measure of rejuvenation effectiveness. Low-temperature mixture embrittlement was evaluated at 210°C through determination of the indirect tensile strength and creep compliance for rejuvenated 100% RAP mixture samples. It can be concluded that four of the nine tested rejuvenators reduced extracted binder consistency to the necessary level and reduced susceptibility of RAP mixtures to low-temperature embrittlement. Of the four, two engineered products tested had notably different performance but neither was superior to similar generic oils.

No abstract

Dramatically rising asphalt binder cost, dwindling budgets, growing traffic loads, and the desire to find more sustainable paving practices are forcing agencies to seek ways for maximizing the re-use of Reclaimed Asphalt Pavement (RAP). While most of the academic and industrial institutions have been focused on the development of procedures to recycle hot asphalt mixes with up to 40% RAP content, a few industry innovators have refined 100% recycling technologies over the past four decades to a level where routine production of 100% recycled mixes is in clear sight. The main hindrance in the widespread use of 100% recycling is the unproven performance of 100% RAP pavements and lack of a unified and rational system for selection of materials and mix design. The objective of this research was, therefore, to critically investigate the concept of 100% recycling, determine whether such mixtures can perform as well as conventional asphalt mixes and if yes, develop a mixture design method for 100% recycled asphalt. This article presents a summary of the research, demonstrating that with adequate mixture design 100% recycled asphalt mixtures can perform equally to conventional asphalt. The available production technologies are also shortly summarized. Finally an environmental effect and cost calculation is performed demonstrating reduction of emission by 35% while reducing the costs of materials by half.

No abstract