A STUDY ON CHANGE OF FAMILY COMPOSITION AND PROPERTIES OF LIAOSHU PAVING ASPHALT ON AGING

In this paper the change of family composition of the paving asphalt, which conforms to the standard of Sinopec Q/SHR-004-1998, was studied under continuous heating and atmosphere at three different temperatures (150, 163, 180°C), at the same time, the changes of pavement performance were studied. The results showed that at three different aging temperatures saturated hydrocarbon contents did not obviously change after 20 hours on aging. The change of aromatic contents was different before and after 20 hours while resins and asphaltenes contents have changed noteworthily. After aging, resins decreased noteworthily, asphaltenes increased obviously, the composition and structure of asphalt were destroyed which had the pavement performance go bad.

     

STUDY OF SERIAL REACTION KINETICS AND CHANGES OF GROUP COMPOSITIONS OF PETROLEUM ASPHALTS IN CONTINUOUS HEAT AND AIR AGING

The serial reaction kinetics and the changes of group compositions of Shengli petroleum asphalt(SPA) and Huansanlian petroleum asphalt(HPA) were studied during continuous heat and air aging(CHAA) at 120 ∼ 180°C. The test results show that at given temperature the contents of saturate constituents of two asphalts change very little, aromatic constituents decrease clearly and asphaltenes increase gradually during CHAA. At lower temperatures(120 ∼ 140 °C) the contents of resins increase slowly and no toluene insolubles form obviously, but at higher temperature(180°C) the resins increase at first and then decrease and the toluene insolubles increase much quickly with the CHAA time. The higher the CHAA temperature, the more evidently the change of asphalt group compositions would change. The apparent aging rate constants and the apparent aging activation     

STUDY OF SERIAL REACTION KINETICS AND CHANGES OF GROUP COMPOSITIONS OF PETROLEUM ASPHALTS IN CONTINUOUS HEAT AND AIR AGING

ABSTRACT

The serial reaction kinetics and the changes of group compositions of Shengli petroleum asphalt(SPA) and Huansanlian petroleum asphalt(HPA) were studied during continuous heat and air aging(CHAA) at 120 ～ 180°C. The test results show that at given temperature the contents of saturate constituents of two asphalts change very little, aromatic constituents decrease clearly and asphaltenes increase gradually during CHAA. At lower temperatures(120 ～ 140 °C) the contents of resins increase slowly and no toluene insolubles form obviously, but at higher temperature(180°C) the resins increase at first and then decrease and the toluene insolubles increase much quickly with the CHAA time. The higher the CHAA temperature, the more evidently the change of asphalt group compositions would change. The apparent aging rate constants and the apparent aging activation     

THE EFFECT OF ASPHALT COMPOSITION ON THE FORMATION OF ASPHALTENES AND THEIR CONTRIBUTION TO ASPHALT VISCOSITY

Interactions among asphalt components have significant effects on the performance of asphalt binder. To understand those interactions, four asphalts, SHRP AAA-I, AAD-I, AAF-I, and AAG-I, were fractionated into three generic fractions according to Corbett's procedure and reblended into asphaltenes/aromatics/saturates ternary mixtures in various ratios. Mixtures were oxidatively aged with atmospheric air at temperatures of 87.7, 93.3, and 98.8°C for 5 to 33 days. The changes in chemical composition and physical properties were monitored using fourier transform infrared spectroscopy (FT-IR) and dynamic mechanical rheometry

The formation of asphaltenes is a major factor in the hardening of asphalt with aging. The data collected in this study indicate that the saturate content in the maltene phase has a profound impact on the contribution that asphaltenes have on the viscosity of aged asphalt. The data also suggest that the aromatics fraction is solely responsible for the formation of asphaltenes as an asphalt oxidizes.     

Effect of Chemical Nature on the Susceptibility of Asphalt to Aging

The knowledge of the factors affecting the susceptibility of asphalt to aging can be of help when selecting the asphalt binders for the construction of durable pavements. Investigated were the aging-induced changes in the chemical composition and colloidal nature of asphalts differing in origin and technology. It was shown that the course of the changes in the generic composition of asphalt upon aging under laboratory conditions depends on the chemical type of the feedstock from which the asphalt has been derived. During aging of the asphalts from the paraffin-naphthenic crudes, the resins undergo partial decomposition, which results in the increase of the cyclic fraction content. Although the increase of the asphaltene content in air-blown asphalts after the Thin Film Oven Test was found to be lower than that in the corresponding straight-run asphalts, the much higher value of the instability index and smaller size distribution of asphaltenes in the air-blown asphalts permit us to expect that their utilization as binders in pavement construction will lead to the reduction of pavement durability. It follows from the results of this study that not only the generic composition but also the structure of the fractions affect the resistance of asphalt to aging.     

Effect of Chemical Nature on the Susceptibility of Asphalt to Aging

Abstract

The knowledge of the factors affecting the susceptibility of asphalt to aging can be of help when selecting the asphalt binders for the construction of durable pavements. Investigated were the aging-induced changes in the chemical composition and colloidal nature of asphalts differing in origin and technology. It was shown that the course of the changes in the generic composition of asphalt upon aging under laboratory conditions depends on the chemical type of the feedstock from which the asphalt has been derived. During aging of the asphalts from the paraffin–naphthenic crudes, the resins undergo partial decomposition, which results in the increase of the cyclic fraction content. Although the increase of the asphaltene content in air-blown asphalts after the Thin Film Oven Test was found to be lower than that in the corresponding straight-run asphalts, the much higher value of the instability index and smaller size distribution of asphaltenes in the air-blown asphalts permit us to expect that their utilization as binders in pavement construction will lead to the reduction of pavement durability. It follows from the results of this study that not only the generic composition but also the structure of the fractions affect the resistance of asphalt to aging.     

碱性物质对沥青热老化的影响

对两种沥青进行薄膜烘箱试验（ＴＦＯＴ）和掺加碱性物质的ＴＦＯＴ试验，用沥青蒸发损失率随ＴＦＯＴ时间的变化、沥青化学组成的变化和沥青红外光谱的变化阐述沥青热老化的原因，时比沥青抗老化性能的优劣，考察线性物质对沥青热老化的影响．结果发现：碱性物质使沥青蒸发损失率降低，可能是碱性物质促进沥青吸氧所致；碱性物质促进沥青中重胶质和沥青质的生成，使沥青在１７Ｏｃｍ－１附近的红外吸收强度明显增强，进一步说明碱性物质促进沥青吸氧．沥青ＴＦＯＴ后其重胶质和沥青质增加程度及其在１７０ｃｍ－１处的红外吸收强度变化程度能够表征其抗吸氧老化性能优劣，反映沥青胶体体系变化程度．     

THE EFFECT OF ASPHALT COMPOSITION ON THE FORMATION OF ASPHALTENES AND THEIR CONTRIBUTION TO ASPHALT VISCOSITY

ABSTRACT

Interactions among asphalt components have significant effects on the performance of asphalt binder. To understand those interactions, four asphalts, SHRP AAA-I, AAD-I, AAF-I, and AAG-I, were fractionated into three generic fractions according to Corbett's procedure and reblended into asphaltenes/aromatics/saturates ternary mixtures in various ratios. Mixtures were oxidatively aged with atmospheric air at temperatures of 87.7, 93.3, and 98.8°C for 5 to 33 days. The changes in chemical composition and physical properties were monitored using fourier transform infrared spectroscopy (FT-IR) and dynamic mechanical rheometry

The formation of asphaltenes is a major factor in the hardening of asphalt with aging. The data collected in this study indicate that the saturate content in the maltene phase has a profound impact on the contribution that asphaltenes have on the viscosity of aged asphalt. The data also suggest that the aromatics fraction is solely responsible for the formation of asphaltenes as an asphalt oxidizes.     

A STUDY ON KINETICS OF AGING OF PAVING ASPHALT

In this paper the aging processes of two penetration-grade paving asphalt which conform to the standard of Esson Company have been studied by rotation thin film oven (RTFO). The first order aging kinetic model has been established and some kinetics parameters were calculated. The relationship between pavement properties of asphalt and aging course was revealed. The intervention of oxygen in high temperature caused oxidation reactions, which changed the composition and structure of asphalt, the aging resistant performance of asphalt was weak, and the service performance went to bad.     

A STUDY ON KINETICS OF AGING OF PAVING ASPHALT

In this paper the aging processes of two penetration-grade paving asphalt which conform to the standard of Esson Company have been studied by rotation thin film oven (RTFO). The first order aging kinetic model has been established and some kinetics parameters were calculated. The relationship between pavement properties of asphalt and aging course was revealed. The intervention of oxygen in high temperature caused oxidation reactions, which changed the composition and structure of asphalt, the aging resistant performance of asphalt was weak, and the service performance went to bad.     

天然岩沥青改善道路石油沥青机理研究

随着公路交通量的增加和对路面耐久性要求的提高，改性沥青在我国道路工程中应用越来越多，掺加天然岩沥青是改性方法之一。为了研究天然岩沥青改性普通沥青性能的内在机理和原因，以新疆岩沥青和滨州90号沥青作对比，采用元素分析、红外光谱、分子量、胶粒当量直径测试等技术手段分析了沥青的化学组成与结构。结果表明天然岩沥青中的沥青质和胶质含量高，硫、氮、氧等杂原子含量高，增加沥青质和胶质的极性，天然岩沥青与普通沥青混合后，分子极性大为增强，分子的缔合能力增强，沥青质分子相互吸引形成胶核，向外依次吸附胶质、芳香分和饱和分形成胶团结构，提高沥青的粘滞性、粘附力及沥青体系稳定性；羧基、羰基、醛等表面活性基团可改善沥青在集料表面的吸附，增加了沥青的抗水损坏性能。     

原位红外研究沥青的热氧老化过程

用四组分法将沥青分为饱和分、芳香分、胶质、沥青质。采用原位红外研究了四组分在不同气氛下的热氧老化过程。研究表明，在氮气氛围下，各组分均无明显老化现象。在氧气中，饱和分和芳香分的热氧化速度最快，在空气中次之。在氧气或空气中，胶质和沥青质的热氧老化程度很弱。同时分别在饱和分和芳香分中加入一定量的不同添加剂，通过研究其热氧老化过程考察添加剂对饱和分和芳香分抗氧化性能的影响。     

Influence of asphalt chemical composition on moisture susceptibility of asphalt mixtures

To evaluate sensitivity of moisture damage resistance with chemical composition of asphalt, the adhesion energy, debonding energy as well as compatibility ratio of 69 asphalt-aggregate combinations were calculated with thermodynamical models. Pearson correlation analysis and regression analysis were carried out to correlate the relationships between asphalt chemical composition (saturates, aromatics, resins, asphaltenes, and wax) and moisture stability of asphalt mixture. The results showed that more resins and less asphaltenes in asphalt could lead to better moisture stability of asphalt mixture under dry and wet conditions, which can be effectively predicted by multiple regression models with different asphalt chemical components.     

EFFECTS OF THE BITUMEN POLAR FRACTIONS ON THE STABILITY OF BITUMEN AQUEOUS DISPERSIONS

The flocculation of aqueous bitumen emulsion during transportation and processing depends mostly on the electrical properties of bitumen-water interface. The aim of this study is to show how such interface is affected by the resins/asphaltenes ratio (r/a) of the bitumen. Our results indicate that the r/a controls the interfacial composition and the stability of the bitumen droplets in a water-continuous medium. Moreover, it is shown that the r/a is primarily responsible for maintaining diffusion of polar components inside the bitumen droplet. Such non-equilibrium behavior of various bitumen polar components takes place during the dispersion manufacturing and/or maturation phase. In this work, the asphaltenes and resins contents of a bitumen series were determined. In addition, the acid-base properties of the same bitumen series were studied by non-aqueous potentiometric titration method. The nature and the amount of acidic and basic functionaliti present in the bitumen were evaluated by comparison with the acid-base model compounds such as carboxylic acid, benzoic acid and pyridine. Furthermore, the interfacial properties of the acidic aqueous bitumen dispersions were studied by contact-angle and zeta potential measurements. The overall results indicate that stable bitumens dispersions are obtained with bitumens having high values of the resins/asphaltenes ratios.     

EFFECTS OF THE BITUMEN POLAR FRACTIONS ON THE STABILITY OF BITUMEN AQUEOUS DISPERSIONS

The flocculation of aqueous bitumen emulsion during transportation and processing depends mostly on the electrical properties of bitumen-water interface. The aim of this study is to show how such interface is affected by the resins/asphaltenes ratio (r/a) of the bitumen. Our results indicate that the r/a controls the interfacial composition and the stability of the bitumen droplets in a water-continuous medium. Moreover, it is shown that the r/a is primarily responsible for maintaining diffusion of polar components inside the bitumen droplet. Such non-equilibrium behavior of various bitumen polar components takes place during the dispersion manufacturing and/or maturation phase. In this work, the asphaltenes and resins contents of a bitumen series were determined. In addition, the acid-base properties of the same bitumen series were studied by non-aqueous potentiometric titration method. The nature and the amount of acidic and basic functionaliti present in the bitumen were evaluated by comparison with the acid-base model compounds such as carboxylic acid, benzoic acid and pyridine. Furthermore, the interfacial properties of the acidic aqueous bitumen dispersions were studied by contact-angle and zeta potential measurements. The overall results indicate that stable bitumens dispersions are obtained with bitumens having high values of the resins/asphaltenes ratios.     

沥青质分子结构与沥青材料性能关系的分子模拟

沥青是一种分子组成多样且介观相态构成复杂的黏弹性材料,其骨架结构为沥青质组成的高贮能模量相,常温环境在外力作用下以弹性响应为主.为了研究分子结构对沥青材料性能的影响,利用分子动力学模拟方法研究不同结构的沥青质在沥青工作温度(250～353 K)区间内的相态,并近似地用剪切模量和杨氏模量分别对各相的切向与正向应力-应变关...     

The Mechanism of Asphalt Modification by Crumb Rubber

To investigate the mechanism of asphalt modification by crumb rubber,the interactions between FCC slurry and rubber particles were evaluated at different temperatures and time.The rules of the change in mass of SARA composition in FCC slurry were obtained before and after its interaction with rubber particles,which showed that crumb rubber not only absorbed saturates and aromatics but also resins.Asphaltenes promoted the desulfurization or degradation of crumb rubber during the interaction between asphalt and crumb rubber.     

EFFECT OF PHOTOOXIDATION ON MOLECULAR WEIGHT DISTRIBUTIONS OF CORBETT ASPHALT FRACTIONS BY GEL PERMEATION CHROMATOGRAPHY

Oxidation of asphalt is believed to be one of the major contributing factors to the failure of asphalt pavement. Due to molecular complexity, the oxidation mechanism of asphalt is complicated by interactions among the molecules of different types. To minimize the interactions, the asphalt sample was separated into saturates, naphthalene aromatics, polar aromatics, and asphaltenes. These Corbett fractions were then oxidized under ultraviolet irradiation. Gel permeation chromatography was used to analyze the molecular weight changes of the Corbett fractions during photooxidation. All Corbett fractions have shown significant increase in molecular weight. The oxidized saturates have the highest weight average molecular weight and the most complicated molecular size profiles among the oxidized Corbett fractions     

EFFECT OF PHOTOOXIDATION ON MOLECULAR WEIGHT DISTRIBUTIONS OF CORBETT ASPHALT FRACTIONS BY GEL PERMEATION CHROMATOGRAPHY

ABSTRACT

Oxidation of asphalt is believed to be one of the major contributing factors to the failure of asphalt pavement. Due to molecular complexity, the oxidation mechanism of asphalt is complicated by interactions among the molecules of different types. To minimize the interactions, the asphalt sample was separated into saturates, naphthalene aromatics, polar aromatics, and asphaltenes. These Corbett fractions were then oxidized under ultraviolet irradiation. Gel permeation chromatography was used to analyze the molecular weight changes of the Corbett fractions during photooxidation. All Corbett fractions have shown significant increase in molecular weight. The oxidized saturates have the highest weight average molecular weight and the most complicated molecular size profiles among the oxidized Corbett fractions     

Influence of Chemical Composition on the Physical Characteristics of Paving Asphalts

The simplest general compositional model considers asphalt to be made up of asphaltenes, heavy oils, and resins. In the present study the extent of similarity between the properties and composition of various types of asphalt obtained from different sources has been carefully explored. It shows how ductility, penetration, and softening point are related to the chemical nature of paving asphalts in the range 41-58 softening points. Asphalt properties are found to be a direct function of its chemical constituents. The relationship between softening point and asphaltene content was found to be linear while asphalts of the same softening point are easily distinguished by the content of the resins. Evaluation of the two asphalt indices—the asphaltene index (I_A) and the Gaestel index (I_C), reveals that they both vary linearly with the composition of asphaltenes and resins thus confirming their suitability in the characterization of asphalts. Comparison of the two indices shows that IC is more suitable in estimating the colloidal stability of different groups of asphalts. The observed correlations can be found useful in the areas of asphalt blending and rejuvenating through the appropriate selection of asphalt components.