Chemical Composition Of Bitumen Research Articles

Influence of Reed Fiber Length and Dosage on the Properties of Reed-Fiber-Modified Bitumen and Bituminous Mortar

In order to explore the feasibility and efficacy of reed-fiber-modified bitumen (RFMB), three lengths and three dosages of reed fibers were selected to modify bitumen and bituminous mortar, while the physicochemical properties of RFMB and RFMB mortar were analyzed. In this work, FTIR spectroscopy was employed to characterize the chemical impact of fiber on bitumen. The viscidity and rheology of RFMB and the tensile strength of RFMB mortar were evaluated using a Brookfield viscometer, dynamic shear rheometer, and monotonic tensile test. The results showed that adding fibers primarily affects the physical structure rather than the chemical composition of bitumen, confirmed by FTIR spectroscopy. RFMB viscosity increased with higher fiber dosage and fiber length. Rheological evaluations showed an enhanced complex shear modulus for RFMB, suggesting improved performance at higher temperatures but increased stiffness at lower temperatures, with the latter indicating reduced flexibility. RFMB also demonstrated superior fatigue and rutting resistance, albeit with compromised stress sensitivity. Tensile tests on RFMB mortar highlighted significant improvements, especially with longer fibers, while shorter 0.4 mm fibers showed modest reinforcement effects, possibly due to uneven distribution during sample preparation.

Relationship between chemical composition and VOCs emission potential of similar paving grade road bitumen

ABSTRACT Exposure to bitumen fumes of workers during road pavement is a subject of interest in the field of industrial hygiene. Improvements have been made to technical means of prevention, but recent studies have shown that exposures need to be reduced. The development of early diagnosis method able to assess the volatile organic compounds (VOCs) emission potential would therefore be useful. The objective of this study was to outline a possible relationship between the chemical composition of bitumen and VOCs emission during heating using thirteen 35/50 paving-grade bitumen samples used in France. The samples are similar regarding their physical properties, elemental and SARA compositions. Molecular analysis investigations show that they contain the same class of compounds but in different proportions. Thermal analyses revealed different capacities of volatiles release potential. The combination of these data allowed to establish a relationship between chemical composition and volatile emission, leading to the identification of two groups of samples. We suggest three parameters based on molecular weight distribution, thermogravimetric profile and hydrocarbon release capacity that may distinguish bitumen by their emission potential prior to road pavement application. They may contribute to a methodology aiming to prevent workers exposure to bitumen fumes.

Investigating the link between the chemical composition of bitumen and the kinetics of the styrene-butadiene-styrene swelling process

Changes in bitumen production processes and crude sources can affect the chemical composition of the bitumen and the quality of the final polymer-modified binder products. As the rheological properties of the final products are of great importance, this study utilises systemic rheology along with functional indices determined from Fourier transform infrared spectroscopy and bitumen fractions to find a link between the chemical composition of bitumen and the kinetics of the polymer swelling process. The results show that the substitution mode of aromatic rings and the colloidal index significantly correlate with swelling parameters. The presence of weakly condensed aromatic rings reduced the swelling rate and elongated the swelling extent. Furthermore, a lower colloidal index resulted in a lower modification degree. It is possible to conclude that the outcomes of chemical studies conducted on the base bitumen are related to the swelling kinetics of styrene–butadiene-styrene-modified binders.

Chemical and Foaming Analysis on Cold Mix Asphalt Performance with Recycled Asphalt Pavement

Cold-mix asphalt has been developed in recent years by combining foamed asphalt and recycled asphalt pavement (RAP). However, manufacturers struggled due to the less standardized specification. Foaming and mixing performance cannot be accurately controlled and are usually treated with a foaming agent (FA). This research focused on the relationship between the chemical composition of bitumen and its foaming properties. Three groups of AC-20 bitumen and organo-modified siloxanes based FA with water content of 1.5%, 2.0%, 2.5%, 3.0%, 3.5%, 4.0% and 4.5%. were analyzed. Chemical components of different bitumen types were evaluated using the Gaestel colloidal index (CI). The half-life (HL), expansion ratio (ER), Foam index (FI), and bubble surface area index (SAI) were used to evaluate the workability of the binders and discuss the effects of the values on the performance of the mixture. The CI observation revealed that FA obviously changed the saturates value and greatly improved the foam properties in terms of stability and expansion. FI change was found to be 71% of the change in the CI. Similarly, the resulting FI and SAI reach up to 88% in terms of correlation.

Do chemistry and rheology follow the same laboratory ageing trends in bitumen?

The ageing of bitumen has received great attention both from a chemical and rheological perspective due to its direct impact on asphalt performance. However, open questions with respect to the convergence of the synchronous ageing changes in rheology and chemistry of bitumen still exist. This paper addresses these alterations of chemistry and rheology and attempts to establish a link via fitting rheological equations fed by fundamental chemical information. To that end, three binders of different type were used in four different laboratory ageing states. A number of spectroscopic techniques and rheological testing were employed to derive corresponding chemical and rheological parameters. In parallel, various statistical methods (Bivariate analysis, Wilcoxon test, Factor analysis) assisted in identifying relationships among the chemo-rheological parameters and simplifying the number of variables. The results of this study demonstrate that chemistry and rheology are following similar changes when considering laboratory ageing following the fast-rate phase of a dual oxidation scheme and short-term lab ageing. Finally, this work manages to establish a linking framework for a number of newly-introduced rheological parameters. All in all, the results of this study might be particularly interesting for future interventions in the chemical composition of bitumen, considering its effect on performance.

Evaluation of the effect of thermal oxygen aging on base and SBS-modified bitumen at micro and macroscales

This study investigates the changes and relationship between micro and macro properties of base bitumen and styrene–butadiene–styrene (SBS)-modified bitumen during aging. Fourier infrared spectroscopy and atomic force microscopy were used to observe the changes in the microstructure and chemical composition of bitumen during aging and the change of morphology was quantified. The thermal stability of bitumen during aging was also studied via thermogravimetry and differential scanning calorimetry. The results show that with increase in aging severity, bitumen is gradually oxidized and SBS molecules in SBS modified bitumen are gradually degraded. Quantitative analysis of the micromorphology of bitumen shows that the area of bitumen’s bee-shaped structure gradually increases as the aging degree increases, and the number and total area of bee-shaped structures gradually decrease. Additionally, pressure aging vessel aging has a great influence on the bee-shaped structure. The addition of SBS modifier will reduce the magnitude of these changes; thus, modified bitumen exhibits better aging resistance. During the aging process, the initial decomposition temperature of the two bitumen types will increase to varying degrees, whereas the maximum decomposition rate temperature remains unchanged. The phase transformation heat absorption of bitumen gradually decreases as it ages, and its thermal stability improves. The addition of SBS modifier will increase the specific heat capacity of bitumen, but this effect will be weakened as it ages. Additionally, there is a good correlation between the micromorphology, chemical composition and macro thermal stability of bitumen.

Laboratory Performance Evaluation on the Recovering of Aged Bitumen With Vegetable Oil Rejuvenator

Generally, the conventional rejuvenator contains many mineral oils to supply the missing components of aged bitumen. The mineral oils could recover the performance of aged bitumen go through a long-term aging process. However, the mineral oils are easy to volatilize at higher recycling temperature. The higher volatilization will reduce the effect of rejuvenator and limit proportion of reclaimed asphalt pavement (RAP) in recycled asphalt mixture (RAP contents less than 30%). The main components of vegetable oil are straight chain higher fatty acids and glycerides. The esters of straight chain higher fatty acids and glycerol are not volatile at high temperature. Therefore, they can be used to recover the micro chemical composition of bitumen and a change in colloidal stability of asphaltene. In this research, two newly kinds of bitumen rejuvenator were developed by replacing mineral oil with waste cooking corn and soybean oil. The two kinds of vegetable and a mineral bitumen rejuvenators were utilized to recover aged bitumen with 2–10% by weigh. The objectives of the research are evaluating the rheological properties, high temperature and fatigue performance of the recovered bitumen. The Dynamic Shear Rheometer Test and Rotational Viscosity Test were conducted according to the AASHTO and ASTM standards. Additionally, the crack resistance of bitumen was evaluated by using the bending beam rheometer (BBR) test at −12 and −18°C. The result of laboratory test and statistical analysis of ANOVA showed that the vegetable oil rejuvenators effectively reduce the viscosity and stiffness of aged bitumen. It will improve both the fatigue resistance and low temperature crack resistance. In addition, when the content of vegetable oil is higher, the rejuvenating agent can make the recovered bitumen have lower viscosity and stiffness. Considering that the rutting resistance under high temperature, it is suggested that 6 and 8% vegetable oil be used to recover the aged bitumen.

Bitumen fractionation: Contribution of the individual fractions to the mechanical behavior of road binders

Anticipation of alternative road binder to replace petroleum derived bitumen requires a deep understanding of relationships between the chemical composition of bitumen and their physical properties, especially rheological ones. The vast number of the different molecules constituting bitumen is too complicated to unravel, thus in this paper we propose to fractionate bitumen into four fractions and study their different physico-chemical properties. The melting temperature and the glass transition of each fractions was determined by DSC while their molecular weight distribution was determined by HS-SEC. Finally, their rheological properties were investigated by DSR. This study highlighted the importance of all bitumen phases: the less polar liquid phase driving the viscous behavior up to −50 °C, the more polar solid phase responsible of the thermal stability and the stiffness, and finally the intermediate viscous oily phases allowing the molecular weight distribution continuity and by consequence allowing to have, on a large temperature range, a viscous liquid behavior at high temperature or low frequency, and an elastic stiff behavior at low temperature. Crystallizable fractions and asphaltene aggregates seemed to act as key molecular structures in the continuous phase.

Investigating bitumen long-term-ageing in the laboratory by spectroscopic analysis of the SARA fractions

Ageing is an omnipresent phenomenon that affects all materials in earth’s atmosphere including roads. The material most prone to ageing within an asphalt road is its organic binder, i.e. bitumen. The quality and chemical composition of bitumen can be affected by the crude oil source and refinery process. Hence, they can show differences in long-term performance and ageing susceptibility, even when being within the same specification class.To investigate long-term-ageing (LTA) in the laboratory, three binders from different crude oil sources, but within the same specification class, were aged with two different laboratory LTA procedures, chemo-mechanically investigated, separated into four SARA fractions and analyzed with FTIR spectroscopy. The results revealed that a clear differentiation between ageing methods and crude oil source can be obtained by chemo-mechanical correlation as well as on the molecular level (SARA fractions). While standard laboratory ageing (Pressure Ageing Vessel – PAV) reaches a similar ageing level for each binder, the second LTA method (Viennese Binder Ageing – VBA) leads to different ageing levels for the samples and is therefore a more suitable tool to distinguish ageing susceptibility. The fractions mainly show the formation of carbonyls and sulfoxides as well as a slight increase in certain sections of the fingerprint area. By combining these techniques, we aim at achieving a thorough investigation on the molecular level and link it to the binder level. This should help us to detect differences in ageing susceptibility, crude oil origin and refinery processes.

An investigation into the influence of aging and rejuvenation on surface free energy components and chemical composition of bitumen

The present work aims to study the influence of Waste Vegetable Oil (WVO) as a rejuvenator on the properties (physical, chemical and surface free energy (SFE)) of aged bitumen and assess the interaction between rejuvenator and aged bitumen in such blends. The study also investigated the relation between SFE components and SARA (acronym for Saturates, Aromatics, Resins and Asphaltenes) fractions in aged and rejuvenated bitumen. The SARA analysis was carried out by employing Thin-layer chromatography with flame ionisation detection (TLC-FID) technique. The SFE components of the bitumen for both aged and rejuvenated bitumen were determined by measuring the contact angles with different probe liquids using a sessile drop device.The test results on bitumen aged to different construction and in-service conditions suggested that the non-polar component of SFE (γLW) decreases with aging, which is due to a decrease in non-polar saturates and aromatics as demonstrated by TLC-FID analysis. However, the increase of the polar asphaltenes was not reflected in the trend for the polar component of SFE (γ+−) which was attributed to the aggregation of the asphaltenes into clusters in extremely aged bitumen. The findings from the study also suggested that γLW correlates, inversely, well with asphaltenes concentration rather than total SFE (γTotal) (or) γ+−.

Degradative Effect of I.R Radiations on the Constituents of Bitumen

Sample of natural bitumen were taken from bitumen well in Agbabu town in Odigbo Local Government of Ondo State. These samples were separately irradiated with infrared radiations for a period of seven hours. Part of the sample was withdrawn at interval of One, Three and Seven hours. The withdrawn sample was later separated into maltene and asphaltene fractions. The maltene fraction was further separated into saturated, aromatic and polar fraction. The saturated and aromatic fractions were subjected to gas chromatography analysis. The Saturated and aromatic profiles of the bitumen were found to vary with the period of irradiation. The Chemical composition of both the saturated and aromatic compounds in the bitumen decreased with the period of irradiation. Thus, decrease in the chemical composition of bitumen as a result of irradiation cause aging of bitumen. Therefore, I.R radiations were found to have a degradative effect on the composition of bitumen.

Application of infrared spectroscopy and partial least-squares for modeling the correlation of bitumen dynamic shear rheological with temperature

ABSTRACTThis paper reported a method for determining the correlation of the physical properties and the chemical composition of bitumen. The double-log model of dynamic shear modulus with temperature was performed for linearization treatment to obtained the constants, which were served as the independent variables using in partial least-squares(PLS) regression. In addition, infrared spectra were processed by data pretreatment methods and served as dependent variables in PLS. The regression vector b of PLS made possible the observation of the spectral regions contributing in the modeling, which provided a basis for research of the correlation between physical properties and chemical composition of bitumen.

Relation between bitumen chemistry and performance

The relation between the chemical composition of bitumen and the physical properties, such as viscosity or viscoelasticity is very important for the use of bitumen as an advanced construction material. In view of the limited understanding of the exact molecular structure of the millions of different molecules constituting bitumen, many different proposals for the structure of bitumen have been published over the last 100years. In this paper we propose that interactions between the molecules are the main determinants for the physical properties of bitumen. We discuss different types of interactions, typical for hydrocarbons, such as dispersive London interactions, polar interactions and pi–pi interactions, and how the strength of the interactions may be estimated by different methods. We also discuss one class of molecules in bitumen, defined by non-solubility, the asphaltenes, and why they contribute strongly to the thickening effect of bitumen, but we also conclude that asphaltenes are not the only molecules contributing to viscosity. Finally we show how the use of molecular parameters like molecular weight and aromaticity can be used to give a good estimate of the viscosity of heavy hydrocarbons of different composition.

The Chemical Composition of Bitumen in Pyrolyzed Green River Oil Shale: Characterization by 13C NMR Spectroscopy

During oil shale pyrolysis at high temperature, the conversion of kerogen to oil and gas proceeds dominantly through a mechanism involving bitumen as a reaction intermediate—at low maturities bitumen is formed from decomposition of kerogen, while at high maturities bitumen is transformed primarily to oil and gas. Here, we study the chemical composition of Green River bitumens of a range of maturities by high-field 13C nuclear magnetic resonance (NMR) spectroscopy. Numerous trends in the evolution of bitumen with maturity are observed, some of which are similar to trends previously observed in kerogen while others are not. As found previously for kerogen, bitumen becomes more aromatic (less aliphatic) with increasing maturity. However, in contrast to kerogen, which is primarily consumed during maturation and was found previously to have aliphatic chains that become shorter and/or more branched with maturity, aliphatic chains in bitumen lengthen with maturity in the low maturity regime where bitumen is prim...

Identification of four material phases in bitumen by atomic force microscopy

ABSTRACT The identification of material phases at the so called bitumen-scale in context of multiscale modeling of asphalt is presented. For this purpose, atomic force microscopy (AFM), providing insight into the surface topography and mechanical properties, is applied to different types of bitumen. Based on the obtained AFM results, four different material phases at the bitumen-scale are identified. These phases are related to the chemical composition of bitumen, characterized by a wide range of molecular mass. Within the anticipated multi-scale model, the properties of these phases serve as input for upscaling, providing material parameter of the bitumen phase at the next-higher scale, i.e., the mastic-scale.