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。     

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.     

Influence of Chemical Composition on the Physical Characteristics of Paving Asphalts

Abstract

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.     

Construction asphalt prepared by chemical treatment of deoiled asphalt

The 30# construction asphalt was prepared by chemical condensation of deoiled asphalt (DOA) from vacuum residue propane deasphalting in this study. It decreases the penetration and improves the softening point of DOA effectively based on the chemical condensation technology from experimental results. The group components of DOA were regulated through the addition of furfural extract oil dewaxed oil (DWO) with high content of aromatic components. Therefore, the ductility of condensed asphalt still meet the requirements of construction asphalt in the condition of decreased penetration and increased softening point. The 30# construction asphalt satisfies the standard requirements of the GB/T494-2010 by chemical condensation technology through the effective control of condensation degree with the appropriate blending proportion of DWO. The binary linear mathematical models of the properties of condensed asphalt have been established by regression analysis of the experimental data. This model had the high accuracy and excellent practical values. The properties of condensed asphalt could be accurately predicted and the construction asphalt production cost could be reasonably controlled. In addition, there was little change in the softening point of the construction asphalt pre and post thermal storage, which illustrated that the 30# construction asphalt obtained by chemical condensation of DOA has good thermal storage stability.     

PPA改性沥青性能及机理分析

加入PPA改性剂后,其沥青的软化点得到了提高,混合料的性能试验结果表明,其高温性能得到了大幅度的提高,但却降低了混合料的抗水损能力。加入抗剥落剂后其水稳定性得到恢复。采用沥青质快速沉淀套色板以及核磁共振分析PPA改性沥青的化学组分。分析认为,PPA优先与沥青质发生作用,所发生的化学反应引起沥青微观结构和组分的变化,从而提高了沥青的高温性能,扩大了沥青PG分级的范围。     

Characterization of hard-grade asphalt using entropy analysis

By adopting different technologies and raw materials, several kinds of hard-grade asphalts were prepared, and the correlation between performances and chemical compositions for these hard-grade asphalts was investigated based on grey relation entropy analysis. Results indicated that nine types of hard-grade asphalts were in accordance with GB/T 15180-2010 standard for 30# asphalt, although they have obvious differences in the performances. The main factors influencing high temperature performances were the presence of aromatics and resins and molecular weight distribution, while the main factors influencing temperature susceptibility were the presence of saturates and asphaltenes and the unstability of colloids. While there has been slight difference in E_r(X_i) for ductility (10°C and 15°C), the remarkable factors influencing the crack resistance at low temperature (stiffness and m value) were the presence of aromatics and resins and molecular weight distribution, in accordance with high temperature performances.     

MOLECULAR MECHANICS OF AGGREGATES OF ASPHALTENES AND RESINS OF THE ATHABASCA OIL

An analysis of the effects of an almost continuous chemical distribution of asphaltenes and resins on the molecular recognition processes occurring in crude oil indicates that their aggregates will have a broad distribution both in the chemical composition and in the strength of the intermolecular interactions responsible for the aggregation. Then, crude oil cannot be described just as a sol formed by solid asphaltene particles dispersed by resins or as a simple micellar system of asphaltene and resin molecules. The molecular aggregates may vary from solid particles formed by asphaltenes and resins to loosely bound micelles with quite short lifetimes. These different aggregates may coexist within the crude oil and many will exchange components with others. The entropic contributions to the changes in free energy upon aggregation were also discussed. Molecular mechanics calculations showed that a model asphaltene aggregate from Athabasca exhibits stronger interactions with its resins than with solvents such as toluene and n-octane. The resins showed a considerable selectivity for the different adsorption sites of the asphaltene aggregate. This selectivity was stronger than that found for the solvent molecules, indicating that it is enthalpically more favorable for them to form aggregates with the asphaltenes. The selectivity may also help to explain the specificity of some resins that are able to disperse only the asphaltenes of certain types of crude oils while failing to do the same for others.     

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．     

泡沫沥青再生混合料水稳定性的试验研究

在室内试验的基础上，根据泡沫沥青再生混合料的物理特征和强度影响因素．探讨提高该材料水稳定性能的技术措施，包括拌和用水量、泡沫沥青用量、细料掺量、掺加活性填料和工后养护。随后通过国内外的工程经验总结对比，给出泡沫沥青再生混合料水稳定性能的评价指标和技术要求的建议值。     

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.     

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.     

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.

     

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.     

The influence of different minerals on the mechanical resistance of asphalt mixtures

The adsorption of five asphalts processed in Brazilian refineries and designated as A, B, C, D and E, and their asphaltenes and maltenes constituents, from toluene solutions, onto quartz, feldspar and biotite and the relationship between this tendency and the mechanical properties of the asphalt pavement have been investigated. For all minerals asphalts A and C strongly absorbed the others. Their respective curves levelling off between 3.5 and 4.0 mg g^− 1 for gneiss and quartz, increasing to 5 and 6 mg g^− 1 for feldspar and biotite. The eletrophoretic mobility of quartz was not modified by the adsorption of asphaltenes in contrast to that observed for feldspar and biotite, indicating that the sites liable for the surface charge of the latter minerals were affected by the presence of the adsorbed organic species. Regarding the mechanical resistance tests for asphalt mixtures, only asphalts A and C gave that would be considered values acceptable by the Brazilian National Department of Terrestrial Infra-structure (DNIT) (> 80%). Those results indicate that the chemical interaction among minerals and asphalts should affect for good or bad the mechanical resistance of the asphalt mixture.     

Influence of resins and asphaltenes on thermal transformations of hydrocarbons of paraffin-base heavy crude oil

Thermal transformations of petroleum components of paraffin-base heavy crude oil and oils (hydrocarbon concentrate), a mixture of oils and resins (maltenes), and a mixture of oils with asphaltenes isolated from the crude have been studied in order to assess the effect of resins and asphaltenes on the hydrocarbon conversion direction. Thermolysis of samples has been conducted at 450°C for 2 h in the isothermal mode. Data on the material balance of the process have been obtained, and the composition of the gaseous and liquid products of thermolysis has been determined. The gaseous products of thermolysis consist of hydrogen, carbon dioxide, and C₁–C₅ hydrocarbons. It has been shown that the thermolysis of all the samples is accompanied by the appearance of newly formed resins and asphaltenes. Analysis of the dynamics of changes in the hydrocarbon composition of the liquid thermolysis products has shown that the resins, rather than asphaltenes affect to a greater extent the direction of hydrocarbon cracking reactions.     

Enhancing the performance of blown asphalt binder using waste EVA copolymer (WEVA)

Air blowing of asphalt generally decreases the penetration value of asphalt binder so that asphalt becomes more brittle and more susceptible to crack during thermal cycling. The aim of this study is to improve the elasticity of blown asphalt upon blending with 3%, 5%, and 7% by weight of thermoplastic waste EVA copolymer (WEVA). Physico-chemical characteristics of blended samples like (FTIR and TGA) were discussed. In addition, the physical properties including penetration test, softening point, ductility test, and elastic recovery were studied. The chemical constituents of asphalt binder including oils, resins, and asphaltenes fractions were investigated using solvent extraction technique. Also, the flow properties of dynamic viscometer at different shear rate were also measured. Moreover, the mechanical properties including storage modulus, tan δ, and stress relaxation were analyzed with dynamic mechanical analyzer at temperature range (20 °C–80 °C). The sample blended with 5%WEVA demonstrated an enhancement in storage modulus and elastic recovery and decrease in tan δ. Finally the prepared blends were applied on carbon steel panel, the paints showed an improvement in properties such as flexibility, hardness and drying times with good adhesion. The overall results approved that blending with 5 wt% (WEVA) improve the performance of blown asphalt binder.     

高模量沥青混合料路用性能试验研究与评价

为了研究高模量沥青混合料的综合路用性能,通过对AC-25C（30号）、AC-20C（30号）、AC-20C（70号SBS）、AC-25C（70号）沥青混合料的高温性能、低温性能、疲劳寿命和水稳定性等试验研究。对比试验和分析了不同沥青混合料的路用性能,从而比较出高模量沥青混合料的优越性。     

NMR Fingerprinting of Chemical Changes in Asphalt Fractions on Oxidation

Abstract

The composition of asphalt has been the subject of much study because such data are required in determining its performance-related properties. A problem inherent in studying asphalt composition is its chemical complexity; however, the characterization of asphalt can be better achieved by separating into fractions. In this work, the chemical property of commercial-grade asphalt obtained from BAPCO refinery, Bahrain (BH), was carried out. The rolling thin-film oven (RTFO), used for short-term aging, and pressurized aging vessel (PAV), used for long-term aging, ASTM D4124 (1991) method was used to separate fresh and aged asphalt into four generic fractions such as asphaltenes, polar aromatics, naphthene aromatics, and saturates. The Corbett fractionation procedure was used to separate fresh and aged asphalt into four generic fractions such as asphaltenes, polar aromatics, naphthene aromatics, and saturates. Nuclear magnetic resonance (NMR) was employed to fingerprint the chemical changes that occurred in asphalt during the aging processes. NMR measurements of asphalt fractions showed that during aging, isomerization and dehydrogenation types of reactions took place. Significant differences were observed between the structure and composition of fresh and aged fractions of asphalt. Results from NMR spectrometry provided significant information concerning the chemical transformations that occurred during the aging processes.     

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.     

纤维在沥青混合料中的应用研究

选用工程中常用的几种纤维,结合工程应用要求,试验分析了纤维的吸湿性、耐热性,并通过网篮析漏试验、动态剪切试验和沉锥试验,讨论了纤维对沥青的稳定和吸附作用,以及纤维对沥青混合料“加筋”效果和作用机理。研究表明有的纤维“吸附、稳定”性能好,而有的纤维“加筋、桥接”效果好,在应用纤维时,应根据纤维的主要特点以及沥青混合料的使用要求来选用。