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Gel permeation chromatography (GPC), Corbett analysis, Heithaus test and other physical and chemical tests have been used to characterize asphalts and to relate chemical properties, physical properties and performance. The asphalts used in the present study consisted of periodic samples of virgin asphalt from various suppliers to Texas in the last two years, the test pavement asphalts in Dickens, Dumas and Lufkin, Texas from study 287, and a group of asphalts which had been rated according to tenderness.
In this project the researchers studied a correlation between molecular structure and corresponding compositional analysis of asphalt binders of conventional hot mix asphalt mixtures (HMA) as well as mixtures containing reclaimed asphalt pavement (RAP) and/or recycled asphalt shingles (RAS) with their cracking potential at intermediate temperature. The molecular size and structure of asphalt components of RAP and RAS undergo large changes during their exposure to environmental factors, which affects the physical properties imparted to their mixtures with conventional asphalt liquids. The composition of the mixtures prepared using a PG 70-22M binder was ascertained using thin layer chromatograpy/FID detection (Iatroscan), gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The distribution of species by molecular mass as determined by deconvoluting gel permeation chromatographs, emphasizing in particular, the amount of asphaltenes as they are related to the age hardening of asphalt materials. The extent of sample aging is apparent from the carbonyl oxygen content from FTIR measurements of the mixtures. Fracture resistance of laboratory produced mixtures was assessed using the Semi Circular Bend Test (SCB) test procedure; a minimal value of 0.5 kJ/m2 was considered acceptable. Mixtures containing up to 5% RAS, 15% RAP and 15% RAP/5% RAS met the SCB standard. Molecular fractionation through GPC of mixtures containing RAS confirmed the presence of highly associated asphaltenes in greater concentrations than mixtures containing recycled asphalt pavement (RAP). High concentrations of high molecular weight associated asphaltenes (mol wt > 20K Daltons) which are present in RAS samples decrease the fracture resistance of the asphalt mixtures. The use of recycling agents, Cyclogen-L, Hydrogreen, Asphalt Flux and Re-refined engine oil bottoms (REOB), did not reduce the concentration of the highly associated asphaltenes, further they failed to improve the cracking resistance of the asphalt mixtures evaluated in this study. However, the recycling agents effected quantitative extraction of the RAS asphalt component.
This book is a printed edition of the Special Issue "Advanced Asphalt Materials and Paving Technologies" that was published in Applied Sciences
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1 957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 32 (thesis year 1987) a total of 12,483 theses titles from 22 Canadian and 176 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 32 reports theses submitted in 1987, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.
The design and construction of “long and deep” tunnels, i.e. tunnels under mountains, characterised by either considerable length and/or overburden, represent a considerable challenge. The scope of this book is not to instruct how to design and construct such tunnels but to share a method to identify the potential hazards related to the process of designing and constructing long and deep tunnels, to produce a relevant comprehensive analysis and listing, to quantify the probability and consequences, and to design proper mitigation measures and countermeasures. The design, developed using probabilistic methods, is verified during execution by means of the so called Plan for Advance of the Tunnel (PAT) method, which allows adapting the design and control parameters of the future stretches of the tunnel to the results of the stretches already finished, using the monitoring data base. Numerous criteria are given to identify the key parameters, necessary for the PAT procedure. Best practices of excavation management with the help of real time monitoring and control are also provided. Furthermore cost and time evaluation systems are analysed. Finally, contractual aspects related to construction by contract are investigated, for best development and application of models more appropriate for tunnelling-construction contracts. The work will be of interest to practising engineers, designers, consultants and students in mining, underground, tunnelling, transportation and construction engineering, as well as to foundation and geological engineers, urban planners/developers and architects.