摘要:

A comparison between spectrophotometry and gravim-etry to study MSD of asphalt is presented. Spectrophotometry suffers from not detecting saturated compounds, as well as from variation of molar absorptivity during analysis. To address this, an asphalt sample is fractionated, and the relative molar absorptivity determined for each fraction. Using another sample weight of the whole asphalt, the saturates are separated, and injected to get their MSD using refractive index detection. This information - when used to mathematically treat the whole asphalt distribution data - can correct the latter to include saturates as well, but can only partially account for continuous variation of the molar absorptivity.

ISSN:0884-3759    

DOI:10.1080/08843759208916004

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

This paper discusses two techniques to characterize the type and measure the strength of asphalt-aggregate bonds. The Modified Lottman Test is commonly used to measure the physical strength of asphalt-aggregate bonds. Under certain conditions bonds may become weak due to chemical factors that are not accounted for in the Modified Lottman Test. In order to measure the chemical strength of the bond, a chemical preconditioning stage was introduced prior to performing the Modified Lottman Test. During this stage a compacted mix pill was exposed to an environment that was rich in either OH−- or Hplus;ions. Such high or low pH conditions affect bonding reactions that are reversible in nature, and thereby expose the chemical weakness of the bond. Results show that different antistrip agents react differently to such conditions. The paper also discusses the effect of mix curing on bond strength under these limiting pH conditions. The other technique discussed in this paper, U a test that characterizes different aggregates in terms of their reactivity with aspnaltic components, which subsequently helps identify those aggregates that would form strong bonds with asphalt. It was observed that even within limestones aggregates, different types reacted to a different extent, and thereby, could be easily characterized

ISSN:0884-3759    

DOI:10.1080/08843759208916005

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The objective of this work was to determine the feasibility of modifying asphalt AAK-2 and AAM-2 by elimination reactions. The dehydrohalogenation reaction and the dealkylation reaction were investigated. Brominated asphalt AAK-2 and AAM-2 can be produced via free-radical chain reaction. The dehydrobrominated asphalt AAM-2 showed an increase in large molecular size (LMS) materials, no elastic recovery and an increased ESR free radical signal intensity. However, the dehydrobromination modified asphalt AAK-2 showed an increase in elastic recovery compared to the original asphalt. In this case, no increase in the ratio of the ESR signal intensity of vanadyl porphyrins to free radicals was observed. The dealkylation reaction modified asphalt AAK-2 showed an increased elastic recovery and a weight average molecular weight reduction, due to its high sulfur and nitrogen content. The ratio of the ESR signal intensity of vanadyl porphyrine to free radicals was decreased. A plot of log [ESR signal intensity ratio] versus aging index yielded a straight line for eight core asphalts studied. Therefore, an increase in the free radical concentration in asphalt may correlate with the loss of elastic recovery, increased W S materials and increased viscosity. The feasibility of modifing asphalt MK-2 and AAH-2 vas successfully demonst Gated: The results obtained here not oil; provide methods for chemically modifying asphalt but also provided information on - oxidation - reactions of asphalt nitrogen content. The ratio of the ESR signal intensity of vanadyl porphyrine to free radicals was decreased. A plot of log [ESR signal intensity ratio] versus aging index yielded a straight line for eight core asphalts studied. Therefore, an increase in the free radical concentration in asphalt may correlate with the loss of elastic recovery, increased W S.

ISSN:0884-3759    

DOI:10.1080/08843759208916006

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Spray and chip seals are the most important form of road surfacings in Australia. The long term hardening of the asphalt binder (its durability) is of critical importance in determining their life. The Australian Road Research Board (ARRB) Durability Test measures the intrinsic resistance of an asphalt cement to oxidative hardening and has been used in specifications for many years. A model which allows calculation of the rate of asphalt hardening in a sprayed seal has already been presented. It is based on data from road trials monitored for up to 15 years.

ISSN:0884-3759    

DOI:10.1080/08843759208916007

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0884-3759    

DOI:10.1080/08843759208916008

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The hydrocracked residues were found to be considerably enriched both in total nitrogen and in basic nitrogen relative to total nitrogen with respect to the feed asphalt. The matrix in which these basic nitrogen components are most likely to be found consisted of compact aromatic structures containing relatively few naphthenic and paraffinic moieties

ISSN:0884-3759    

DOI:10.1080/08843759208916009

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Using microscopic techniques by UV fluorescence reflexion. It was possible for the first time to observe the natural segregation of two incompatible polymers (a polyolefln and a SBS triblock copolymer 5:1) In several asphalts. This method helped in identifying and understanding the relationship between microstructure and performance of polymer/asphalt blends. Performance of the binders such as elongations! behaviour, low temperature flexibility and high temperature performance were studied before and after ageing. The polydispersity of the phases and the fineness of the SBS dispersion were shown to be very sensitive to the blending conditions, the composition of the asphalt and Its susceptibility to ageing. The ability of the dispersed SBS to form a continuous matrix under elongational stress was crucial to observe elastomeric behaviour. It was shown that there was an optimum in the asphaltene content in order to allow the elastomeric matrix formation without any loss in cohesion at the polymer/asphalt interface as visualized by microscopy

ISSN:0884-3759    

DOI:10.1080/08843759208916010

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A new. less costly method of extracting bitumen from asphalt pavament mixtures has been developed which gives bitumen contents essentially the same as those obtained by the currently used centrifuge method. The preferred solvent is cyclohexane (although cyclopentane may be used) at high temperatures and pressures. The new method uses these non-chlorinated solvents at high temperatures and pressures (but sub-critical) to dissolve and extract asphalt from the mix in a stainless steel extractor vessel. Although these solvents are less hazardous to the health of the laboratory personnel than chlorinated solvents, they can be a fire hazard unless reasonable precautions are exercised

ISSN:0884-3759    

DOI:10.1080/08843759208916011

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

UV/VIS absorption spectra of a few bitumens and their main generic fractions obtained by liquid chromatography have been recorded. Major or minor differences have been found depending on the nature of the bitumen and the generic fraction considered. Those differences are a valuable help in interpreting measurements of binder-aggregate affinity. A spectrophotometry technique has been tried in order to assess this affinity from a physicochemical point of view. It is baaed on the adsorption equilibria in solution between the bitumen or one of its generic fractions and a ‘and’ grading fraction of the aggregate. Both the asphaltenes of the bitumen and the nature of the aggregate play a considerable part in binder-aggregate interactions. The influence of the nature of the aggregate depends mainly on the specific surface of the ‘sand’ fraction used in the tests: with a 0.15 to 0.4 mm fraction this specific surface may vary by a factor up to more than 10, according to the nature of the original aggregate. Orientation tests to obtain more information about the generic fractions have been positive. The asphaltenes can be separated into cyclic-like and resin-like asphaltenes and the resins can be divided into resins with an ‘acid’ or ‘basic’ behaviour

ISSN:0884-3759    

DOI:10.1080/08843759208916012

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The condition of ten roadways constructed between February 1983 and Hay 1984 has been evaluated with respect to distortion, cracking, raveling, rutting, and overall condition. These observations have been correlated with laboratory measurements of rheological and chemical properties of the refinery liquid from which the roadway was made. Rheologic parameters include penetration, ductility, and viscosity. Chemical measurements include elemental analyses, fractionation into asphaltenes, oils, and resins, infrared and C-13 nuclear magnetic resonance spectra, molecular size of asphalt components by high performance liquid chromatography, and solvent solubility

ISSN:0884-3759    

DOI:10.1080/08843759208916013

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor