Saturates, Aromatics, Resins And Asphaltenes Research Articles

Evaluating the effect of paper waste lignin in hot mix asphalt

Asphalt is a viscoelastic material which performs to resist rutting, fatigue cracking, and moisture susceptibility under different loading and temperature conditions. The use of innovative and renewable pavement construction materials is inevitable due to high axle loads, rapidly increasing traffic volumes, and varying climatic conditions. This study aims to assess the effect as well as the optimum dosage of paper waste lignin for use in hot mix asphalt (HMA). Lignin from the paper industry with dosage ratios of 5, 10, 15, and 20%, was utilized to study the effect of the addition of lignin to the asphalt binder. Virgin and lignin-modified binder samples, before and after the aging process, were subjected to physical testing through penetration, softening point, ductility, viscosity and specific gravity and rheological characteristics through dynamic shear rheometer (DSR), bending beam rheometer (BBR), and rational viscometer (RV). The fractional composition was assessed through saturates, aromatics, resins and asphaltenes (SARA) fractional composition technique. Statistical analysis was also performed to find correlation of different physical and rheological parameters. Furthermore, based on optimum dosage, the performance of asphalt mixtures was studied against rutting, fatigue cracking, and moisture susceptibility. The results indicated that the addition of lignin has improved the physical properties significantly. The amount of asphaltene decreased and aromatics increased in SARA fractional analysis. Moreover, the Colloidal Instability Index (CII) has also indicated a stable structure of the binder. The rheological characteristics are improved after modification. The asphalt mixture tests revealed that addition of lignin with optimum dosage (10%) has improved the performance against rutting, fatigue cracking and moisture susceptibility. Statistical analysis indicated good co-relation among different physical and rheological parameters. This study concludes that 10% dosage is the optimum dosage that can successfully replace the virgin asphalt binder for performance of hot mix asphalt.

Molecular reconstruction of crude oil and simulation of distillation processes: An approach based on predefined molecules

Utilizing molecular management is a robust method for tackling the obstacles presented during the worldwide energy shift and for streamlining the utilization of crude oil resources. A fundamental component of this management technique is molecular reconstruction technology. In this study, a molecular model of crude oil is constructed using 151 deterministic molecules and artificially constructed molecules with average structures. To establish the molecular property matrix, the group contribution method and molecular dynamics simulations are employed to compute the molecular properties. An optimization algorithm is then employed to convert true boiling point profiles, SARA (Saturate, Aromatic, Resin, and Asphaltene) contents, and API of crude oils into detailed molecular content distributions. These distributions, alongside the actual boiling point curve data, are integrated into chemical process simulation software to model the distillation process of the crude oil. Notably, the molecular weights and mass densities of the process outlet streams derived from these two calculations are generally in good agreement.

Effect of oxidation kinetic aging on the adhesion behaviour of asphalt-aggregate interfaces from molecular view

ABSTRACT Asphalt oxidation kinetic aging effect on the adhesion behavior of asphalt-aggregate interfaces at atomistic scale was investigated in this study. The asphalts were aged at different aging durations. The sulfoxide and carbonyl functional group content as well as SARA fractions of the asphalts at different aging times were studied through the tests of Fourier Transform Infrared Spectroscopy (FTIR) and Saturate, Aromatic, Resin and Asphaltene (SARA) fractions. Asphalt molecular models of virgin, rapid-rate aged, slow-rate aged and full-aged were established based on SARA fractions and FTIR results, to construct asphalt quartz and asphalt-calcite interface systems at different aging stages. The simulation results showed that the nanostructure of asphalt is influenced by the aggregate type and asphalt oxidative aging. The growth rates of adhesion energy of asphalt-quartz and asphalt-calcite systems increase rapidly first and then slowly with aging time, but the growth rates are different. Meanwhile, the Van der Waals energy is the major energy source of adhesion energy, and the contribution of van der Waals and electrostatic energy to adhesion energy is different. The aging of asphaltene and resin promotes the adhesion ability to quartz or calcite, while the aging of aromatic components is not conducive and the saturate has almost no effect.

Chemical and rheological analysis of unaged and aged bio-extended binders containing lignin

The use of alternative renewable sources to totally or partially replace bitumen is one of the most current challenges in the road pavement sector. The growing energy cost and environmental concerns lead to the necessity to find alternative solutions, by supporting at the same time sustainability and circular economy principles. Within this framework, this paper presents the application of a powder lignin, a natural bio-polymer deriving from by-products of wood pulp and paper industry, to replace part of bitumen. The bituminous blend consisting in 70% of bitumen and 30% of powder lignin (by weight) was made in laboratory through the use of a high shear stirring mixer, and a reference plain bitumen characterized by a similar consistency (i.e., same penetration grade) was used as comparison. Then, an extensive investigation on chemical and rheological properties of the bio-binder is presented. Fourier transform infrared spectroscopy (FTIR), saturates, aromatics, resins and asphaltenes (SARA), bending beam rheometer (BBR), frequency sweep tests and multiple stress creep recovery tests (MSCR) with a dynamic shear rheometer (DSR) were performed. Moreover, unaged, short- and long-term aging conditions were considered. Results indicated that powder lignin dominates the rheological behavior of the bio-binder and, from chemical analysis, it seems that it partially acts as a filler and partially as a binder. This would result in improved performances at both low and high temperatures, leading to a wider temperature range of performance grade (PG). Moreover, despite a stiffening effect is recognized, lignin also offers an antioxidant potentiality, reducing the aging susceptibility of the investigated bio-binder.

Simplified regular solution model for asphaltenes precipitation in crude oil blends

The regular solution model is used with Hankinson-Brobst-Thomson (HBT) molar volume correlation for saturates, aromatics, resins and asphaltenes (SARA) fractions for pure crude oils and blends to predict the precipitation of asphaltenes. The parameters of the HBT correlation were tuned with experimental data for SARA fractions densities. At the same temperature and pressure conditions, the precipitation of asphaltenes is greatly influenced by the presence of other compounds. SARA fractions were obtained according with ASTM D2007 using n-heptane as precipitant solvent. The use of average properties for saturates, aromatics and resins and the assumptions made in the model could reproduce precipitation curves for all study cases. Calculations of asphaltene precipitation prediction for pure oils showed an average absolute deviation between 0.12 and 0.69% for oil of Gulf of Mexico and Cold Lake oil, respectively. For blends it showed values between 0.08 and 0.65% for Cold Lake/Lloydminster-Asphaltene free blend and Cold Lake/Lloydminster-Gulf of Mexico blend respectively. The proposed model maintains its simplicity and can predict the asphaltene precipitation accurately.

Chemical Viscosity Reduction of Heavy Oil by Multi-Frequency Ultrasonic Waves with the Main Harmonics of 20–60 kHz

Ultrasound technologies are well-known for their ability to intensify the heat and mass transfer processes. Hence, ultrasonic treatment processes are widely applied for the separation of oil–water emulsions, optimization of oil pumping processes, cleaning the bottomhole zone, etc. However, the main phenomenon under the positive influence of ultrasonic waves on such processes is the cavitation bubbles implosion on the water–oil boundary. It is well-known that ultrasound energy contributes to the reversible viscosity reduction in heavy oil systems. However, it is possible to exhibit chemical destruction of the weakest carbon–heteroatom bonds in the structure of the asphaltenes. This study investigates the influences of controllable ultrasound waves with frequency ranges of 20–60 kHz under the exposure time of 60 s on the rheology of a heavy crude oil sample produced from the Ashalcha reservoir (Tatarstan Republic, Russia). The specific feature of this study is the application of multi-frequency ultrasonic exposure with a wide spectrum of side harmonics with the frequency up to 400 kHz. The results of the Saturates, Aromatics, Resins and Asphaltenes (SARA) analysis method support the chemical consequences of ultrasonication of crude oil. The content of resins under the irradiation of ultrasound waves altered from 32.5 wt.% to 29.4 wt.%, while the number of aromatics hydrocarbons raised from 24.3 wt.% to 34.1 wt.%. The Gas Chromatography—Mass Spectroscopy (GC-MS) analytical analysis method was applied to qualitatively compare the composition of saturated and aromatics fractions between the initial and upgraded heavy crude oil in order to show the chemical destruction of asphaltene bonds after the ultrasonic treatment. It was demonstrated that ultrasound waves allowed chemical conversion of asphaltene fragments that led to irreversible viscosity reduction. The viscosity of the heavy oil sample under the favorable ultrasonic irradiation conditions reduced from 661.2 mPa·s to 178.8 mPa·s. This advantage can be used to develop enhanced oil recovery methods and partial upgrading processes in downstream conditions.

Evaluation of the state of practice asphalt binder and mixture tests for assessing the compatibility of complex asphalt materials

The present study aims to evaluate binder and mixture testing methods for capturing the compatibility of complex asphalt materials consisting of different virgin binder sources, reclaimed asphalt pavement (RAP) materials and recycling agents (RA). Binder evaluation methods include the saturate, aromatic, resin and asphaltene (SARA) fractionation, advanced polymer chromatography (APC) analysis, differential scanning calorimeter (DSC) and rheological measurements. Mixture performance tests include the complex modulus (E*), direct tension cyclic fatigue (DTCF), disk-shaped compact tension (DCT) and semi-circular bending (SCB) fracture tests. The results from the testing and analysis indicate that the rheological characterisation of asphalt binder or mixture may not capture the incompatibility between virgin binder, RAP and RA. Binder DSC analysis as well as mixture fracture tests have shown promise to evaluate the compatibility of complex asphalt materials with different virgin binders, RAP and RA, as well as the effect of incompatibility on mixture performance.

Molecular simulation and experimental analysis on co-aging behaviors of SBS modifier and asphalt in SBS-modified asphalt

ABSTRACT Styrene-butadiene-styrene block copolymer (SBS) is the most commonly used asphalt modifier. Studying the aging process of SBS-modified asphalt and clarifying the role of SBS and asphalt in the aging process can provide a basis for the targeted regeneration of SBS-modified asphalt. In this research, the physical and chemical changes of SBS and asphalt in the aging process were studied by FTIR (Fourier Transform Infrared Spectroscopy) analysis and SARA (Saturate, Aromatic, Resin, and Asphaltene) analysis. The effects of the thermal oxidation of asphalt and SBS on the viscosity and tensile properties of the SBS-modified asphalt were investigated by Brookfield Rotational Viscosity Test, force ductility test, and molecular dynamics simulation. Furthermore, the influence of asphalt and SBS aging on the adhesion property of the asphalt-aggregate interface was analyzed. The results show that the impact of SBS aging on the increase of viscosity and tensile yield stress was far less than that of asphalt aging. The adhesion energy of the modified asphalt-silica interface increases with both aging of SBS and asphalt. SBS and asphalt jointly influence the performance of modified asphalt in the aging process, but asphalt aging is the dominant factor.

Evaluating the ageing degrees of bitumen by rheological and chemical indices

The ageing of bitumen is an inevitable phenomenon which is still challenging to be characterised. This paper aims at evaluating the ageing degrees of bitumen comprehensively. There were six types of bitumen being aged to five levels for comparing purposes and multiple rheological tests by a DSR as well as chemical test for the SARA (saturates, aromatics, resins and asphaltenes) properties of bitumen were carried out. The critical temperatures, G-R parameter and nonrecoverable-compliance-based ageing indices were proposed to evaluate the ageing degrees of bitumen in terms of low-, intermediate- and high-temperature performance of bitumen, respectively. Also, a novel ageing evaluation index based on the integration of modulus of master curves was employed and modified, which can evaluate the ageing degrees of bitumen accurately in terms of the whole range of temperature. Finally, the chemical ageing index were analysed and was confirmed to have strong linear relationship with rheological indices of bitumen.

Prediction of asphaltene stability in crude oils using machine learning algorithms

The main aim of this study is to predict asphaltene stability in crude oil as a function of its SARA (Saturates, Aromatics, Resins and Asphaltenes) values using Machine learning algorithms. For this purpose, four Machine Learning algorithms namely, Linear discriminant analysis (LDA), Linear regression (LR), decision tree (DT), and random forest (RF) were applied to predict the asphaltene stability of 95 crude oils. SARA values of these oil samples were taken as input parameters for the algorithms. The dataset was also visualized comprehensively using different plots. For ML model implementation, 70% of the dataset was used during the training of the model while the remaining 30% dataset was used during the testing phase. For the model's reliability, a 10-fold cross-validation method was applied. Moreover, Recursive feature elimination (RFE) was also applied to determine the effect of feature elimination on the accuracy of models. The performance of all ML algorithms was determined using various statistical metrics. For all ML models, the accuracy was found in the range of 60–80% during the training and testing phase with LDA having the highest accuracy of about 78% and DT with the lowest, i.e., 62% in the training phase. On the other hand, DT accuracy was found to be the highest whereas LDA accuracy was found to be the lowest during the testing phase. The overall accuracy of LDA was observed to be the highest. The Resins feature was found to be the most important parameter for predicting the asphaltene stability in crude oils by all ML algorithms. Moreover, for models robustness, all ML models were run at two different training-to-testing ratios i.e. 80:20 and 60:40. At both ratios, all ML models generally yielded accuracy in the range of 0.6 and 0.8 during training and testing phases similar to the base case i.e. 70:30. Finally, the moderate accuracy of ML models and overall outcome of the study suggests that SARA values alone are not capable enough to determine the asphaltene stability in crude oil with reliability and more features need to be identified for incorporation in the model to improve the accuracy of models.

Experimental study on the enhanced ultra-heavy oil recovery using an oil-soluble viscosity reducer and CO2 assisted steam flooding

Ultra-heavy oil resources have gained extensive attention due to their abundant reserves and the shortage of conventional hydrocarbon resources. In this work, we investigate the feasibility of recovering ultra-heavy oil resources using an oil-soluble dissolver, i.e., a type of viscosity reducer, and CO2 assisted steam flooding (DCS flooding) by studying the impact of those agents on oil properties and EOR performance of this approach. Firstly, the effects of steam, CO2, and the oil-soluble dissolver on the oil properties are investigated by comparing the variations in oil viscosity, SARA (saturates, aromatics, resins, and asphaltenes) compositions, asphaltenes structural parameters, and asphaltenes morphology. Then, the feasibility of DCS flooding in improving ultra-heavy oil recovery is investigated by comparing its performance in core flooding experiments with steam flooding and CO2 assisted steam flooding schemes. Next, the sensitivity of various agents in DCS flooding is analyzed by conducting DCS flooding experiments with different amounts and concentrations of those agents. Finally, the chemical components of the produced fluids are analyzed to further understand the dynamic EOR mechanisms of the DCS flooding. The results demonstrate that the oil-soluble dissolver exhibits the best oil viscosity reduction (56.1%) performance through decomposing the asphaltenes of ultra-heavy oil. Meanwhile, DCS flooding presents promising performance in improving ultra-heavy oil recovery (76.78%) compared with steam flooding (59.6%) and CO2 assisted steam flooding (65.26%). Moreover, DCS flooding is also beneficial to decrease maximum steam injection pressure, control the water cut, and improve steam dryness.

Comparison of column chromatography and solid-phase extraction on virgin and aged bituminous maltene phases

Bitumen is a complex mixture consisting of different hydrocarbons, which can be categorised into substance classes called SARA (saturates, aromatics, resins and asphaltenes) fractions. The saturates, aromatics and resins are further referred to as maltenes or maltene phase. To determine the SARA fractions the asphaltenes were separated from the maltenes in a first step. A standard method to further separate the maltenes is column chromatography (CC). Since column chromatography is a time-consuming and solvent-intensive process, an alternative method for separating maltenes using solid-phase extraction (SPE) was investigated. A total of nine bitumen samples of the same type in different ageing states but from different manufacturers were separated with both methods to determine the mass percentages of the fractions for investigating their comparability. The results show that both methods led to different mass percentages of the fractions. However, with the SPE, separating smaller amounts of maltenes is possible while saving a large amount of material, costs, and workload. Linear regression analyses between the colloidal indices with conventional and rheological parameters revealed that the fractions obtained from SPE led to higher coefficients of determination of the linear regression model. The obtained fractions were further structurally compared with FTIR spectroscopy, whereby the spectra of the SPE fractions and the CC fractions did not show any significant differences. The overall consideration of the results concludes that the SPE can replace the CC.

Study of hydrogen generation from heavy oil gasification based on ramped temperature oxidation experiments

Hydrogen is a clean energy because of its high energy density and pollution-free combustion. The main ways of hydrogen generation are from coal and methane, as well as hydrogen generation from by-products of chemical plants. It had been reported that heavy oil reservoir in Margaret Lake in Canada produced up to 15 mol% hydrogen indicating that it is feasible to produce hydrogen by in-situ gasification (ISG) from heavy oil reservoir. However, there are relatively few studies on the mechanism and characteristics of hydrogen generation from ISG of heavy oil, the lower limit of hydrogen-production temperature, the interaction of produced gas and so on. Previous studies focused on the upgrading of heavy oil rather than hydrogen generation. In order to study the hydrogen generation mechanisms of different samples, The 4 types samples covering heavy oil, light oil, carbon samples were used and the saturate, aromatic, resin and asphaltene (SARA) components was measured by thin layer chromatography and flame ionization detection (TLC-FID). Then, the ramped temperature oxidation (RTO) experiments of 7 Runs of reservoir cores and sand-filling model were designed. The compositions and molar contents of produced gas were analyzed combined with gas chromatography (GC), and the lower limit temperature and the advantages of hydrogen generation from heavy oil were analyzed under different air/nitrogen injection rates based on a constant water injection rate. The results showed that the lower limit temperature of hydrogen generation from crude oil was about 500–550 °C and that of carbon was 700–750 °C. The reservoir core may had catalytic effect, which can promote hydrogen production. The highest hydrogen rate of RTO experiment with reservoir core can reach 55–60mol%, while that of sand-filling experiment was only 5–10mol%. The main chemical reactions for hydrogen generation from crude oil were coke gasification and water-gas shift. Therefore, the hydrogen production of heavy oil with high hydrocarbon ratio was significantly greater than that of thin oil. It showed the advantages of hydrogen generation from heavy oil. In addition, in order to quantitatively evaluate the efficiency of hydrogen production by gasification, the definition and calculation equation of hydrogen generation efficiency (HGE) were given. The HGE was defined as the ratio of hydrogen production volume and hydrogen consumption volume in a certain period of time (Δt). The Ehg can be used to quantitatively represent HGE, and the calculation of Ehg is the ratio of hydrogen production and twice of oxygen consumption in a period of time. The Ehg of Run1 and Run3 were calculated to be 1.47 and 0.15. It indicated that the hydrogen production efficiency of Run1 was about 10 times higher than that of Run3.

Iron oxide nanoparticles impact on improving reservoir rock minerals catalytic effect on heavy oil aquathermolysis

The past decade has seen a renewed importance in developing heavy oil reserves due to the rapid raise in energy resources’ demand. The next decade is likely to witness a considerable rise in extracting these resources by thermally enhanced oil recovery methods. However, many hypotheses regarding the influence of reservoir mineral components on aquathermolysis reactions appear to be disputable. This paper outlines a new approach to model the aquathermolysis of Aschalcha’s reservoir rock heavy oil in the presence and absence of iron oxide nanoparticles combined with hydrogen donor in water steam atmosphere at 200, 250, and 300 °C using different physical and chemical methods. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) have showed adsorbed spherical magnetite (Fe3O4) nanoparticles with less than 100 nm size on the studied rock minerals in hydrothermal conditions. Moreover, SARA (Saturates, Aromatics, Resins and Asphaltenes) analysis, gas analysis, and gas chromatography–mass spectrometry (GC–MS) have revealed that the obtained iron oxide nanoparticles exhibit their highest catalytic activity at 250 °C comparing to 200 and 300 °C respectively. What’s more, the obtained data have indicated a considerable decrease in resins (from 19.6 to 8.9 wt%) and asphaltenes compounds (from 5.1 to 1.5 wt%) in the presence of iron oxide nanoparticles comparing to the non-catalytic aquathermolysis of reservoir rock heavy oil. Contrary to resins and asphaltenes’ content, it has been found that saturates’ content increases significantly from 41.1% to 61.7% wt%. On another hand, the viscosity of the extracted oil has decreased almost 30 times and the gas proportion has doubled more than twice from 0.2 g to 0.43 g per 100 g of the reservoir rock sample. Interestingly, these results have been obtained in the presence of iron oxide nanoparticles at 250 °C, meanwhile, the same results have been found for the non-catalytic experiments at 300 °C. These findings confirm the significant contribution (synergistic effect) of iron oxide nanoparticles to stimulate the catalytic activity of the reservoir rock minerals. What’s more, the evidence from this study suggests that the presence of iron oxide nanoparticles in hydrothermal conditions at higher temperatures leads to the formation and adsorption of heavy coke-like carbenes, carboides, needle coke as well as carbon nanotubes of 100 nm size on the surface of the reservoir rock heavy oil as confirmed by thermal analysis (TG-DSC), SEM, and drop shape analysis (DSA) data.

Impacts of asphalt and mineral types on interfacial behaviors: A molecular dynamics study

In order to analyze the interfacial interaction mechanism between the types of mineral and asphalt at the molecular scale, molecular dynamics (MD) simulations were conducted to study the interfacial behavior of three asphalt binders (AS-1, AS-2, AS-3) with five minerals (SiO2, CaO, MgO, Al2O3, Fe2O3). Thermodynamic properties of asphalt binder were used to evaluate the rationality of MD simulations, such as density, glass transition temperature, cohesive energy density and solubility parameter. The mean square displacement (MSD), diffusion coefficient and relative concentration distribution were employed to analyze the diffusion regularity of asphalt SARA (saturate, aromatic, resin and asphaltene) components on the mineral surface, and the bonding strength between asphalt and different minerals was evaluated by calculating the adhesion work. The simulation results show that Van der Waals energy and Coulomb electrostatic energy play critical role in the adhesion of asphalt-mineral. The diffusivity of asphalt on the surfaces of five minerals was ranked as CaO > MgO > Al2O3 > Fe2O3 > SiO2. It is enhanced with the increase of alkaline strength of minerals, and then the adhesion work of asphalt-mineral increases. The interfacial adhesion strength of the asphalt binders and minerals are directly related to the proportion of asphaltene and resin components, and the molecular mass of asphalt will affect asphalt-mineral adhesion strength, which can also be reflected by the relative concentration distribution of SARA components on mineral surface.

Using special additives for decreasing the asphaltene content of missan crude oil

In crude oil, asphaltene is one of the fractions that may be dissolved in aromatics like benzene or toluene but cannot be dissolved in alkanes like n-heptane, n-pentane, or petroleum ether (a mixture of alkane compounds). A typical difficulty in oil recovery and refinery processes is asphaltene precipitation, which happens when the oil stream's pressure, composition, or temperature change. So, the stability of asphaltene in crude oil needs to be looked at to find out how likely it is to form asphaltene so that it can be stopped and high treatment costs can be reduced. In the present study, saturate, aromatic, resin and asphaltene (SARA) analysis of Missan heavy crude oil from the (Omar River Field) was performed. Three additives were used to show their effect on asphaltene at different concentrations and temperatures. The additives included nanoparticles (nano ferric oxide red, nano silica oxide, and a mixture of nano silica and ferric oxide red) and the polymer fiberglass. The concentrations of the additives of the nanoparticles were (200 ppm, 3533 ppm, a867 ppm), (1667 ppm, 6667 ppm, 10000 ppm, and 16667 ppm) and (24000 ppm, 40000 ppm, and 48000 ppm) of nano-silica, ferric oxide red, and a mixture of nano silica and ferric oxide red, respectively, while fofiberglassss, 3733 ppm, 7066 ppm, 10400 ppm, and 13733 ppm) and measured at temperatures (5, 25, and 45oC) The best read I got was when it was used. 4.249% from origin to 6.375% after treating the percentage of asphaltene with 48000 ppm of ferric oxide red and nanoo-silica.

Self-Healing Properties of Asphalt Concrete with Calcium Alginate Capsules Containing Different Healing Agents.

Calcium alginate capsules encapsulating rejuvenator are a promising self-healing technology for asphalt pavement, but the effects of different healing agents on the self-healing performance of asphalt concrete has not been considered. In view of this, this paper aimed at exploring the effects of calcium alginate capsules containing different healing agents on the self-healing properties of asphalt concrete. Three types of capsules with sunflower oil, waste cooking oil and commercial rejuvenator were fabricated via the orifice-coagulation bath method and the interior structure, mechanical strength, thermal stability and oil content of the prepared capsules were characterized. The healing levels of asphalt mixtures with different capsules under different loading cycles and stress levels were evaluated. Furthermore, the saturates, aromatics, resins and asphaltenes (SARA) fractions and rheological property of extracted asphalt binder within test beams with different capsules after different loading conditions were assessed. The results indicated that all the three types of capsules meet the mechanical and thermal requirement of mixing and compaction of asphalt mixtures. The healing levels of test beams containing vegetable oil capsules were higher than that of waste cooking oil capsules and industrial rejuvenator capsules. The strength recovery ratio and fracture energy recovery ratio of test beams with vegetable oil capsules reached 82.8% and 96.6%, respectively, after 20,000 cycles of compressive loading at 1.4 MPa. The fracture energy recovery ratio of the waste cooking oil capsules also reached as high as 90%, indicating that waste cooking oil can be used as the healing agent of calcium alginate capsules to improve the self-healing property of asphalt mixture. This work provides a significant guide for the selection of healing agent for self-healing capsules in the future.

Investigating the relationship between chemical composition and mechanical properties of asphalt binders using atomic force microscopy (AFM)

As a complex mixture, the composition-structure-mechanics relationship of asphalt binders is not well-understood. Thus, it is essential to understand the relationship between chemical composition and mechanical properties. Saturate, aromatic, resin and asphaltene (SARA) fractions are crucial chemical components of asphalt binders. At present, the main challenge faced by many researchers is the relationship between the SARA fractions and the microstructure, and how the SARA fractions affect the micro-mechanical properties of asphalt binders. In this paper, the composition-structure-mechanics relationship were studied using atomic force microscopy. The asphalt samples were divided into two groups. Firstly, different kinds of asphalt binders with different SARA content were compared. Then, new asphalt binders were derived and their properties were analyzed. Results show that bee structure appears on the surface of asphalt binders with higher asphaltene and resin contents, it means that the formation of bee structures is related to the aggregate of asphaltene and resin. Moreover, the micro-mechanical properties of the asphalt binders are affected by two fractions rather than a single fraction. The adhesion force increases with the increase in saturate and aromatic contents, and decreases with the increase in asphaltene and resin contents. The Derjaguin–Müller–Toporov (DMT) modulus, storage and loss modulus increase with the increase in asphaltene and resin contents, and decreases with the increase in saturate and aromatic contents. Furthermore, SARA fractions have the same effect on both the micro- and macro-rheological properties of asphalt binders. These findings will help to improve the understanding of the composition-structure-mechanics relationship of asphalt binders, which in turn will aid in optimizing their performance.

Determination of SARA fractions in asphalts by mid-infrared spectroscopy and multivariate calibration

The SARA fractions in petroleum asphalts for road paving play a dominant role in the pavement performance of asphalt binders. In this study, a rapid and accurate determination method of SARA fractions in asphalts was proposed using Mid-Infrared (MIR) spectra and Partial Least Square Regression (PLSR) modeling method. Firstly, the blending and progressive aging process employed in this study successfully prepared 84 asphalt samples with fair differences in their Saturates, Aromatics, Resins and Asphaltenes (SARA) fractions. Secondly, the SARA fractions and MIR spectra of these samples were measured and collected by standard test methods, respectively. Finally, four quantitative calibration models were developed for each fraction using MIR spectra and PLSR method, and the validation results verified the high consistency between the measured values and the predicted values as well as the reproducibility and repeatability of the proposed method. This MIR-PLSR method was able to provide a faster SARA determination than the standard test methods through a single MIR spectrum. It could probably be used for the real-time quality control of asphalt production and the in-situ quality inspection of asphalt materials in road construction using portable equipment.

Algorithm for estimating SARA fraction properties and its application in predicting the densities of heavy oils, bitumen and diluted bitumen with solvents

Using aromatic ring index (ARI) and the densities of saturates, aromatics, resins and asphaltenes (SARA) at any temperature, an algorithm was developed to iteratively estimate the molecular weights and specific gravities (60 °F) of the SARA fractions. The algorithm circumvents molecular weight measurements in reporting SARA fractions properties. Then, using the corresponding state principles the critical properties and acentric factor of the fractions were estimated using the correlations available in literature. Further, applying regular solution theory the densities of heavy oils, bitumen, and five diluted Athabasca bitumen with 5 solvents were predicted from Hankinson-Thomson and a compressed liquid density correlation. The average absolute deviation (AAD) in predicting the densities was found to be 1.33% for 1524 points with temperature range from 288 K to 463 K and pressure from 0.1 to 10 MPa. The method exhibits predictive ability and can be used satisfactorily for any heavy oil/bitumen/solvent system. In order to improve the accuracy of the calculated densities, a constant density translation method can also be applied to the bitumen/oil mixtures. When the translation method was used, the AAD of mixtures was improved to 0.69%. The proposed method was found to be better or comparable to other models in predicting densities.