Chemical Composition Of Asphalt Research Articles

Effect of reactive fumes suppressant DOPO on the chemical composition and performance of asphalt

9,10-Dihydro-9-oxa-10-phosphorophenanthrene-10-oxide (DOPO), recognized for its role as an efficacious fume suppressant, has been shown to mitigate the emission of noxious vapors emanating from asphalt. However, the comprehensive influence of DOPO on the composition and properties of asphalt had remained unexplored. This study embarked on an in-depth examination of the effects of various DOPO dosages on the chemical composition of asphalt, employing hydrogen nuclear magnetic resonance spectroscopy (1H NMR) alongside an exhaustive analysis of asphalt components. Furthermore, the investigation elucidated the consequences of different DOPO dosages on the physical, rheological properties, and aging resistance of asphalt. The results of 1H NMR and component analysis of asphalt disclosed that DOPO engaged in chemical reactions with the unsaturated groups within the asphalt, catalyzing a metamorphosis of saturates into aromatics and resins. Such chemical transformations were instrumental in augmenting the softening point, viscosity, and rutting propensity of the asphalt while imposing a minimal impact on its penetration and ductility. Post exposure to the thin film oven test (TFOT), pressure aging vessel (PAV), and ultraviolet (UV) aging, the DOPO modified asphalt (DMA) exhibited a diminution in the increment of softening point and viscosity aging index relative to the control asphalt. Furthermore, the DMA showcased enhanced retention rates of penetration and ductility, coupled with substantially reduced shifts in complex modulus and phase angle post-aging, underlining its superior aging resistance. Fourier transform infrared spectroscopy analysis revealed a comparatively slower rate of change in carbonyl and sulfoxide groups in DMA after aging, as opposed to the control asphalt. Notably, DMA exhibited enhanced resistance to UV aging relative to TFOT and PAV aging scenarios, a trait attributable to remarkable UV absorption capabilities of DOPO. Fundamentally, DOPO enhanced the high-temperature performance and aging resistance of asphalt while simultaneously diminishing the emission of noxious fumes.

Modifying Effect and Mechanism of Polymer Powder on the Properties of Asphalt Binder for Engineering Application.

For achieving the better modifying effect of polyurethane on asphalt pavement materials, the PUA powder modifier was prepared with fine grinding at the glass transition temperature, and polyurethane-modified asphalt (PUA-MA) with different dosages of modifier was prepared. The impact of the PUA on the physical properties of asphalt binder was studied. The modifying mechanism of PUA on asphalt was explored by investigating the thermal performance and chemical composition of asphalt (thermogravimetric analysis, differential scanning calorimetry test, and Fourier transform infrared spectroscopy). The micrograph of the interactive interface was characterized by scanning an electron microscope. Furthermore, the rheological properties of PUA-MA were also investigated and analyzed. The results indicated that the PUA had a dense structure with few pores on the surface. After mixing with asphalt, it altered the asphalt's internal structure via physical fusion and chemical reaction (carbamate formation). PUA improved the thermal stability of asphalt, enhanced the asphalt's thermal decomposition temperature, and further reduced the thermal mass loss while decreasing the glass transition temperature. The addition and dosage increase in the PUA modifier significantly improved the softening point, viscosity, complex shear modulus, and rutting factor of asphalt. Also, the PUA could improve the elastic recovery ability of asphalt and enhance the rutting resistance of asphalt at high temperatures. However, the crack resistance at low temperatures was not effectively improved (ductility and penetration decreased). When the dosage was 6-9%, PUA-MA had the best high-temperature performance, but asphalt showed poor low-temperature performance at this dosage. This study provides a theoretical reference for popularizing and applying polyurethane as an asphalt modifier in road engineering.

Evaluation of the Long-Term Performances of SMA-13 Containing Different Fibers

To clarify the influence of fiber type on the long-term performance of stone mastic asphalt (SMA), this paper used basalt fiber (BF) and lignin fiber (LF) to modify SMA-13 (SMA with aggregate nominal maximum particle size of 13.2 mm) asphalt mixture. The pavement performances (high-temperature performance, cracking resistance at low and medium temperature, and water stability) of the two kinds of fiber-reinforced SMA-13 were checked under different aging degrees (unaged, short-term aged and long-term aged), scanning electron microscope (SEM) test was conducted to explain the strengthening mechanism of the fibers. Fourier transform infrared spectrometry (FTIR) was used to analyze the changes in the chemical composition of asphalt after aging. The results of the wheel tracking test and uniaxial penetration test showed that the high-temperature performance of the BFSMA-13 (defined as the SMA-13 containing BF) is better than that of the LFSMA-13 (defined as the SMA-13 containing LF) at different aging degrees. The high-temperature performance of BFSMA-13 increases with the increase of the aging degree, while the aging process decreases the high-temperature property of LFSMA-13. The results of the three-point bending test and semi-circular bending (SCB) proved that BFSMA-13 is more capable of deformation and less prone to cracking at low and medium temperatures. The results of the immersion Marshal test indicated that BF can better improve the strength and the water stability of the SMA-13 mixture than LF. The SEM images showed that basalt fibers form a solid three-dimensional network structure in the mixture which could contribute to the strengthening of the mixture. The results of infrared spectroscopy analysis showed that styrene–butadiene–styrene (SBS) degrades during asphalt mixture aging, and that the chemical composition of asphalt changes more after aging in LFSMA-13 than in BFSMA-13. The conclusions of this study help toward further understanding of the performance changes of the SMA-13 mixture during its service life and to guide the selection of fiber additives for SMA-13 mixtures.

Influence of the Chemical Composition of Asphalt and the 3D Morphology of the Aggregate on Contact Surface Adhesion

The influence of the chemical composition of asphalt, the aggregate lithology, and the morphological characteristics of the aggregate on the level of adhesion between the asphalt and the aggregate is investigated. A contactless three‐dimensional (3D) white‐light scanning technique is used to obtain point cloud data of the aggregate particles. Six independent feature parameters are used as evaluation indices to quantitatively describe the multilevel features of the 3D morphology of road aggregates. Methods for analyzing the feature parameters based on the point cloud data of the aggregate are presented. Subsequently, the process and evaluation standard of the adhesion test are improved to quantify the spalling degree of the asphalt film on the aggregate surface under boiling conditions. The influences of the chemical composition of the asphalt and the aggregate morphology on the level of adhesion between the asphalt and aggregate are analyzed, and the compatibility between aggregates with different lithologies and the asphalt is assessed. The results show that the shape factor (SF) can be used to characterize the needle‐flake shape of the particles, the ellipsoid index (E) is suitable to determine the angularity of the aggregate particles, and the 3D joint roughness coefficient (JRC3D) describes the roughness of the particle surface. The type of adhesion between the aggregate and the asphalt includes chemical and physical adsorption; chemical bonding is relatively strong, and the physical orientation force and mechanical interlocking force are relatively weak. Alkaline limestone aggregates should be used with asphalt with a high aggregate content of colloid and asphaltenes. Basalt aggregate with weak alkalinity should be used with asphalt with a high colloid content, and the use of angular aggregates should be avoided. Acidic aggregates with compact shapes, few edges and corners, and rough surfaces should be used prudently.

Research on the impact of mineral type and bitumen ageing process on asphalt-mineral adhesion performance based on molecular dynamics simulation method

ABSTRACT The chemical compositions of asphalt and mineral type are always related to interface adhesion performance, and further affect the field performance of asphalt mixture. This study aims to evaluate the effects of mineral type as well as bitumen types experiencing different ageing process on the adhesion property of interface. Adhesion energy and adhesion work of different bitumen and mineral combinations were calculated in dry or wet condition. Results show that different asphalt ageing mechanisms have significantly different effects on bitumen–mineral interface adhesion performance. Interfacial adhesion work increases with the increase of asphaltene and resin fractions in bitumen. Both sulfoxide and ketone can effectively improve the interface adhesion between bitumen and mineral. Water adversely affects the adhesion of asphalt–mineral interface. Calcite-bitumen has excellent resistance to water stripping for lower adhesion work loss rate than quartz-bitumen combination no matter what SARA or chemical structure of bitumen.

Rheological Properties, Compatibility, and Storage Stability of SBS Latex-Modified Asphalt.

A styrene-butadiene-styrene (SBS) latex modifier can be used for asphalt modification due to the fact of its energy-saving, construction convenience, and economic advantages. The objective of this study was to investigate the influence of asphalt type and SBS latex dosage on the rheological properties, compatibility, and storage stability of asphalt through temperature and frequency sweep, steady-state flow, multiple stress creep and recovery (MSCR) tests, Cole-Cole plots and thermal storage tests. The results indicated that high SBS latex content is beneficial for improving anti-rutting, anti-fatigue, viscous flow resistance, and elastic recovery abilities of modified asphalt. The chemical composition of asphalt had a significant effect on the properties of the SBS latex-modified asphalt. High asphaltenes and low resins were favorable to enhancing anti-rutting and recovery properties but weakened the anti-fatigue, compatibility, and storage stability of modified asphalt. Furthermore, compared to SBS particle-modified asphalt, SBS latex-modified asphalt had greater rutting and fatigue resistance. However, SBS latex-modified asphalt had some disadvantages in compatibility and storage stability. Comprehensively considering the balance of viscoelastic properties, compatibility, and storage stability of SBS latex-modified asphalt, the mixing dosage of SBS latex modifier is recommended at 4.0 wt% which could feasibly replace SBS particle in asphalt modification.

Fatigue and healing performance assessment of asphalt binder from rheological and chemical characteristics

The fatigue and healing performance of asphalt binder affect the durability of asphalt concrete and by extension, asphalt pavements. The objectives of this paper are to (1) estimate the fatigue and healing characteristics of asphalt binder by newly developed linear amplitude sweep (LAS) and LAS-based Healing (LASH) protocols, and (2) investigate the relationship between chemical composition of asphalt and engineering performance. Three neat asphalt binders (Pen-30, Pen-50 and Pen-70) and one SBS modified binder are selected for this study. Experimental results indicate that the SBS binder has advanced fatigue resistance among all tested binders and the softer neat binder with a higher penetration grade generally displays better fatigue performance. The fatigue failure occurrence is a significant threshold for healing potential comparison. The rate of healing (HR) results suggest that the best healing potential is with Pen-70 binder in pre-failure conditions followed by the SBS binder, Pen-50 and Pen-30 binders. However, the SBS binder presents better healing performance than Pen-70 binder in post-failure condition. Further solvency fractionation, into saturates, aromatics, resins and asphaltenes, indicates that the asphaltene content is negatively proportional to the quantified binder fatigue life whereas the HR index is found to be well correlated to the weight percents of saturates and ratio of saturates to aromatics (S/Ar). The combined use of LAS and LASH tests is recommended for effectively distinguishing and designing the fatigue-healing performance of neat and modified asphalt binders. Limiting the contents of asphaltenes would be of help to improve the binder fatigue resistance and either saturates percent or S/Ar parameter should be considered to assure the self-healing potential of asphalt binder.

Influence of asphalt chemical composition on moisture susceptibility of asphalt mixtures

ABSTRACTTo 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.

A Thorough Study on the Molecular Weight Distribution in Natural Asphalts by Gel Permeation Chromatography (GPC): The Case of Trinidad Lake Asphalt and Asphalt Ridge Bitumen

The roadway performance is chiefly governed by the chemical composition of asphalt, which in turn depends on the molecular weight distribution in this product. Gel permeation chromatography is one of the most powerful and convenient analytical technique available for characterizing the entire molecular weight distribution of a bitumen. Molecular weight and polydispersity of two natural asphalts viz. Trinidad Lake asphalt (TLA) and Asphalt Ridge bitumen (ARB) have been determined. The number average molecular weight (Mn) of TLA was 893, whereas that of ARB was 993. It is predicted that TLA will deliver a smoother and higher-quality pavement than does ARB.

Microstructure morphologies of asphalt binders using atomic force microscopy

We investigated microstructure morphologies of three asphalts (SK, Karamay, and Esso) used in China using atomic force microscopy (AFM). The topography and phase contrast images were obtained. Topographic profile and three dimensional images were described. Roughnesses of microstructure were calculated. And the chemical compositions of asphalt were tested to explain the microstructural mechanism of the asphalt. The results show that the topography and phase image in atomic force microscopy are appropriate to evaluate the microstructure of the asphalt binder. There are significant differences in microstructural morphologies including bee-like structure, topographic profile, 3D image, and roughness for three asphalts in this study. There are three different phases in microstructure of asphalt binder. The oil source and chemical composition of asphalt, especially asphaltenes content have a great influence on the microstructure.

Non-Isothermal Degradation Kinetics of Asphalt in Relation to its Chemical Composition

Analysis of the complex and variable nature of the chemical composition of asphalt has been a challenge to engineers and scientists, especially as a means to understand its behavior and suggest ways to improve its properties. In this study, the thermal behavior and the non-isothermal degradation kinetics were analyzed using the isoconversional methods, through Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). TGA and DSC data show gradual change in the mass of the material at increasing temperature, suggesting behavior typical of a homogenous mixture. Kinetic analysis from the TGA data using the Starink modification of the Kissinger-Akahira-Sunose Isoconversional method show an apparent increase in the magnitude of the activation energies at different conversion degree, which suggests a gradual change in the composition of the material at each successive conversion due to a single heat-promoted transformation of each of the components.

Molecular dynamics simulation of asphalt-aggregate interface adhesion strength with moisture effect

This study developed an atomistic simulation framework based on the classical molecular dynamics (MD) method to study the moisture-induced damage at the asphalt-aggregate interface. The interface adhesion strength of the asphalt–quartz system was predicted using MD simulation for the first time. The interface stress-separation curve under tension that was obtained from MD simulation resembles the failure behaviour measured from the pull-off strength conducted at the macroscopic scale. The results show that the presence of moisture at the asphalt–quartz interface significantly reduces the interface adhesion strength. The interface failure process is affected by the chemical compositions of asphalt. The interface adhesion strength decreases as the moisture content increases or the temperature increases. It was found that the atomistic model size (number of atoms) and the loading rate in MD simulation have considerable effects on the predicted interface adhesion strength. The findings from MD simulation provide fundamental understanding of material failure at the atomistic scale that cannot be observed at the normal experimental testing environment for asphalt materials. The MD simulation results can be potentially calibrated and utilised as inputs for higher scale micromechanical models to predict bulk mechanical responses of asphalt mixtures.

Physical and Chemical Properties of Asphalts Associated With Performance

Detailed data were collected from field and laboratory evaluations to determine whether changes in crude oils affect the physical and chemical properties of asphalt binders over time. The test results indicated that asphalt cement properties produced today have the same range of values as those produced in the 1990s. Asphalts with high-viscosity susceptibility were shown to be associated with pavement distress. Field evaluations showed that asphalts with a viscosity susceptibility value lower than 0.088 will perform well without premature failure. Asphalts containing relatively low asphaltenes, particularly those of softer grade, appeared to have a greater probability of producing mixtures that could lead to pavement distress. Data analyses revealed that a good knowledge of the physical characteristics and chemical composition of asphalts can provide a useful tool for distinguishing between asphalts associated with pavement performance.

Chemical Effects of Environmental Factors on Asphalt Aging

Asphalt aging occurs both in the construction period and in the service period of asphalt pavement. It is believed that aging could have a big influence on the rheological mechanical and adhesion characteristics of the asphalt. Asphalt aging is a process associated with a lot of factors as heat, rays, oxygen, and ozone. In the aging process, some chemical compositions of asphalt are subject to be activated by these factors and undergo some chemical changes. A theoretical analysis at a chemical reaction level to the asphalt aging mechanism is presented in this paper. Asphalt aging can be sorted as thermal oxidation aging, ray oxidation aging, and ozone oxidation aging. The thermal oxidation aging usually occurs in the components with chains and double bonds in their molecules. The ray oxidation aging can be found in components with one carbonyl or more carbonyls. Those components with a π key in their molecular structures are prone to the ozone oxidation aging.

Nonlinear Rheological Modeling of Asphalt Using White-Metzner Model with Structural Parameter Variation Based Asphaltene Structural Build-up and Breakage

Abstract Rheological behavior of asphalt is strongly affected by loading conditions, temperature and environment. One of the main challenges in understanding the rheology of asphalt is to relate the chemical constituents and the micro-structure of asphalt on one hand to its rheological behavior on the other hand. In this work, nonlinear rheological behaviour of asphalt was investigated using a structural rheological model. A first order kinetic equation to describe structural changes in asphalt has been incorporated with the nonlinear rheological model of White- Metzner. The resulting set of governing equations was solved numerically to describe the rheology of asphalts. Different modes of rheological testing and asphalts with different compositions were considered. An analysis and comparison of model behaviour with experimental data from the literature is carried out in both stress growth at constant shear rate and oscillatory shear modes. A strategy is proposed for the estimation and tuning of the model parameters based on available experimental data and literature. Qualitatively, the model can capture the rheological behaviour of non-Newtonian fluids such as asphalt under different modes of rheological testing. Quantitative analysis from this work shows that the model describes the rheological behaviour of asphalt for the temperature range of 20 – 60ºC. It is demonstrated that a single set of equations tuned with the steady shear experimental data can be used to predict the nonlinear rheological behaviour of asphalts. In addition, it is shown that the model parameters can be related to the chemical composition of asphalts.

Certain Relationships between Chemical Composition and Properties of Petroleum Asphalts from Different Origin

Certain Relationships between Chemical Composition and Properties of Petroleum Asphalts from Different Origin — Asphalts are classified according to three most commonly measured properties: ductility, penetration and the ring and ball softening point. The present study shows through many examples that these physical characteristics are not discriminating enough. It was revealed that the chemical composition sheds more light on the physical properties of the various grades of asphalt. There were significant differences between the chemical composition of asphalts having the same softening point and from the same origin. Increase in ductility has been accounted for by the high content of resins while lower penetration is due to high asphaltene content. The correlation of two asphalt indices with the composition shows that the Gaestel index (I C ) proves to be a more adequate quality parameter than the asphaltene index (I A ) for the characterization of asphalts. Both indices can be comparatively used to distinguish between asphalts of narrow softening point ranges.

CHANGES IN ASPHALT CHEMISTRY AND DURABILITY DURING OXIDATION AND POLYMER MODIFICATION

The Gulf Countries' environmental conditions are very severe. The temperature zoning study indicate that more than half of Gulf areas experience a maximum seven consecutive days pavement temperature of 76°C (Al-Abdul Wahhab et al., 1997). This has resulted in damage to the road networks in the form of cracking, rutting and deformation. Polymer modification of asphalt is required to increase the resistance to permanent deformation at relatively high temperatures without adversely affecting the properties of the asphalts at low temperature. In this work chemical and performance-related properties of fresh, oxidized, and polymer modified asphalts were evaluated. The physical properties and performance characteristics of asphalts were found to depend on the chemical composition of asphalt. The interactions of polar functionalities actually present or formed during oxidative aging or due to polymer modification, influence the viscosity and related flow properties. The changes in composition of fresh, oxidized and polymer-modified asphalts can be clearly identified from Infrared spectroscopy. NMR spectroscopy enables detailed information about the Carbon-and-hydrogen-types and average molecular/structural parameters of asphalt without separating it into different components.

Changes in rheological properties and chemical composition of asphalts upon aging

Changes in rheological properties and chemical composition of asphalts upon aging

Effect of oxidation temperature on properties and composition of roofing asphalts

1. A study has been made of the effect of oxidation temperature on the mechanical properties of asphalts. 2. A study has been made of the effect of oxidation temperature on the chemical composition of asphalts. 3. It has been established that asphalt oxidation proceeds in two stages. In the first stage, the greatest rate of change in oil and asphaltene contents is observed; in the second stage, the greatest rate of change in resin content is observed, and the amounts of oils and asphaltenes are stabilized. 4. It has been established that the temperature regime of the process affects the oxidation reaction mechanism. The asphalts produced by low-temperature oxidation contain considerably greater quantities of oxygenated compounds.