Bitumen Components Research Articles

New evidence on the origin of ‘bee structures’ on bitumen and oils, by atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM)

Bitumen is a complex mixture whose composition–structure-property relationships are not well-understood. Therefore, it is essential to understand which components may develop microstructures, how and when these features appear, and if they are initiated or influenced by other components. Many studies have reported so-called bee structures as well as other phases on bitumen surfaces. A large number of observations point towards the crystallinity of waxy compounds as an explanation for the bees. However, doubt remains about the origin of the other phases and the possibility of other bitumen components as promoters of the bee formation. In this study, bee structures were investigated using two microscopy techniques: atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). By using model wax compounds, especially blends of waxes differing in melting points and chain lengths, bee structures and surrounding islands were created on featureless bitumen surfaces. Structures very similar to what is observed on a paraffinic bitumen were obtained. This indicates that bees and the surrounding areas both consist of crystallisable components. Moreover, bee structures were also generated on other surfaces, such as mineral oil and a maltene fraction. Bee formation is not limited to bituminous materials and bitumen components are not needed as promotors. Furthermore, CLSM offers possibilities to scan through transparent layers and to investigate surfaces under glass, for example. In contact with such a solid substrate, as well as after water submersion, no microstructural features were observed. Adding a combination of n-alkanes, to transparent oil, induced bee structures at the oil-air interface. The transparency of the oil allowed the visualization of wax crystallization in the bulk, where the added waxes crystallize as small particles. These small crystals are expected to influence the mechanical properties, such as low-temperature stiffening effects, which have been reported for paraffinic bitumen.

Powder bed coating of bitumen with asphaltenes to obtain solid prills for midstream transportation

A continuous increase in the global demand for liquid fuels has led to increased reliance on unconventional sources of fossil fuels such as bitumen. The extraction, midstream transportation, and ultimate processing of heavy oils presents a distinctive set of challenges. For example, the high viscosity of bitumen poses a challenge to its transportation through conventional transportation systems such as pipelines. Conventional approaches to address the challenging rheological properties of bitumen involve dilution of bitumen with natural gas condensates, addition of surfactants, ultrasonic heating, thermal jacketing of pipelines, and high pump pressures. These solutions require considerable investments in infrastructure, frequent inspection and maintenance, and pose a risk of spillage to vulnerable environments. As such, much interest has focused on the design of solid-state transportation methodologies. In this article, we propose a viable and safe transportation alternative wherein bitumen is reconfigured such that the droplets of lighter fractions of bitumen (saturates, aromatics, resins) are encapsulated within conformal shells of asphaltenes. The tendency of asphaltenes to aggregate has been exploited to obtain cross-linked shells without requiring the use of extraneous chemical additives. Thermally mediated crosslinking of the asphaltenes shells allow the microcapsules to hold their form and result in the emergence of mechanical strength. The stress-withstanding abilities and velocity impact resistance of these microcapsules have been studied to establish their viability for industrial use, and demonstrate that microcapsules with diameters of ca. 1.25 mm can withstand stresses as high as 576 kN/m2. Since the bitumen microcapsules have been formulated by simply reconfiguring the intrinsic components of bitumen, they can be readily fluidized by mechanical means to recover the encapsulated lighter fractions. The solid microcapsules demonstrate the viability of solid-state transportation of bitumen via roadways or marine tankers, thereby mitigating a primary impediment to the utilization of viscous oils.

Time scales for steam injection and bitumen production in steam-assisted gravity drainage

Despite technical and economic success of Steam-assisted gravity drainage (SAGD), improvements of its thermal efficiency as reflected by the steam-to-oil ratio (SOR) present challenges. Given that the SOR is a measure of the ratio of the energy invested to the energy (chemical energy in oil) produced and emissions intensity, there is strong motivation to reduce the SOR since the lower the SOR, the lower is the energy invested and emissions produced per unit oil produced. However, there appears to be few directions for modifying SAGD to improve the SOR by adjusting the steam injection strategy or fluid production strategy alone. In this research, multiple steam components and multiple bitumen components are used in a thermal reservoir simulation model to understand the time scales of steam flow and bitumen mobilization, drainage, and production. The results reveal that immediate bitumen response is observed near the well and in the steam-trap liquid pool above the production well whereas the time scale between steam stimulation and bitumen response can be as high as hundreds of days. This brings into question the meaningfulness of the steam-to-oil ratio as a control variable for behaviours far from the well pair.

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.

The effect of progressive aging on the bond strength of bitumen to siliceous stones

Oxidative aging changes the composition of bitumen, and these changes affect the cohesive properties and adhesive properties of the bitumen. While cohesive properties of bitumen have been shown to be negatively impacted by aging, bitumen's bonding strength to stone aggregates can increase. Aging makes bitumen become more polar and gives rise to concentration of oxidized asphaltenes. It is hypothesized that oxidized asphaltenes show stronger interaction with siliceous substrates, promoting bitumen's bonding to siliceous stones such as quartz and granite. This study uses computational modeling and laboratory experiments to evaluate the interaction of progressively aged bitumen with siliceous substrates. To do so, asphalt samples aged from 20 to 60 hours were prepared, and their bonding properties were examined in dry conditions and wet conditions. The study results showed that as bitumen becomes aged and/or exposed to water, its shear thinning increases. Our computational modeling showed oxidation promotes the interaction between bitumen components and silica. In terms of bitumen’s bonding to stones, our modeling results showed that oxidized compounds of bitumen such as asphaltene and resin have higher interaction energies with siliceous surfaces than non-oxidized counterpatrs. Our experiments found that siliceous stones (represented by glass beads in experiment) had greater interaction with aged bitumen than with unaged bitumen. Furthermore, aged bitumen showed even higher interaction with siliceous stones when exposed to water compared to dry conditions, as shown by the moisture-induced shear-thinning index (MISTI) test. The latter observations indicate that water could not diffuse into the interface of aged bitumen and siliceous stones to weaken their bond. The outcomes of the study provide insights pertaining to bitumen’s adhering to stones. It further informs methods related to the extraction of bituminous compounds from reservoir rocks as well as removal of oxidized bitumen from stones when reclaiming old asphalt pavements.

Chemical composition (saturate fraction) of western Iraq natural bitumen

This study aims to explore the main components of bitumen in western Iraq as a natural resource of heavy oil. The raw bitumen studied was fractionated into asphaltene and maltene, and then the maltene was separated into saturated, aromatic and polar fractions. Fourier Transform Infrared (FT-IR), 13 C NMR, Scanning Electron Microscopy–Energy Dispersive (SEM–EDX) and Gas Chromatography (GC) were used to characterize the organic components of the bitumen. Hypothetical average molecules have been diagnosed including bitumen, asphaltene and aromatic according to 13 C NMR methods. The results indicate that the saturated, aromatic and polar compounds in bitumen are 8.24%, 55.67% and 9.93% respectively, while the asphaltene is 26.56%. The bitumen studied contains a relatively high amount of asphaltenes and aromatics fractions, potentially due to a thermal maturation of organic material in the well. However, it may be modified as crude oil derivatives because it contains certain aliphatic hydrocarbons.

Сравнительный анализ методов исследования отложений копоти на местах пожаров

Introduction. Smokes are aerosols that contain sublimating substances and condensing vapors, as well as products of chemical and photochemical reactions. In addition to solid and liquid particles, they contain gaseous products of both complete and incomplete decomposition during combustion process, as well as nitrogen and the remains of unreacted oxygen during combustion. The aerosol substance of smoke that has settled on any surface is called soot, which often acts as an object of fire-technical expertise, and the aggregate of soot particles that form zones of various configurations is called smokiness. Goals and objectives. The aim of the work is to study soot and its components for the development of a comprehensive methodology for the study of fires in determining both the focus and the cause of the fire, as well as the pathways of the spread of hazardous factors of fire at different stages of fire development. The main task of the work is to determine the dependence of the qualitative and quantitative indicators of soot and its component composition on the temperature conditions of combustion of various materials in order to establish the conditions for the course of a fire. Research methods. Field and laboratory methods for the study of soot are considered. Field methods include visual analysis of soot deposits (identifying the configuration of soot, color and intensity of the soot layer) and measuring the electrical resistance of the soot layer using a field contact probe. Laboratory methods include the method of microscopic morphological analysis, the method of thermal analysis, molecular spectroscopy and gas chromatography, which are indirect and direct methods for studying extracted organic components of soot. Results and its discussion. The modern methods of research of soot are analyzed. A scheme of laboratory methods is proposed. It allows carry out full morphological analysis, to evaluate the behavior of soot components during heating and composition of extracted components for solving the problems of studying fires. Regression dependences of the content of bituminous components on the logarithm of the electrical resistance of the soot layer were obtained, which showed that, regardless of the type of combustible material, a transition zone is observed on them, in which, with a relatively small change in electrical resistance, a significant increase in the content of bituminous components is observed. Conclusion. The paper considers an comprehensive approach to the study of extractable components of soot. The obtained dependences of the qualitative and quantitative indicators of soot and its component composition on the temperature conditions of combustion of various materials will improve the quality and level of reliability of information in the study of fires in order to determine the focus and cause of a fire, as well as the ways of spreading hazardous factors of a fire at different stages of its development. Key words: smoke, soot, extractable organic compounds, bitumen components, soot layer electrical resistance, molecular spectroscopy, Boltzmann function, fire investigation.

Interaction mechanisms of polyphosphoric acid and nano clay in bituminous composites

It has been reported that adding polyphosphoric acid (PPA) to bitumen modified with Montmorillonite clay (MMT) makes the bituminous composite less prone to swelling and more resistant to moisture damage, thus improving two major causes of pavement distress. There has been no in-depth study on the underlying mechanism for such a synergistic effect between MMT and PPA. Here, we used laboratory experiments and computational modeling to study how PPA moderates the intermolecular interactions in bitumen modified with MMT. The results showed that PPA had notable interactions with both MMT and bitumen components (BCs); however, PPA's preferential adsorption to MMT was verified by a significantly higher binding energy (−127.3 kcal/mol) for PPA-sealed MMT than for PPA-BCs (−85.9 kcal/mol). The higher binding energy for PPA-sealed MMT caused PPA to be strongly adsorbed on the MMT surface in the first stage, causing partial intercalation into the clay gallery and blocking subsequent entry of water. PPA's affinity to interact with BCs then allowed PPA to be a bridge between MMT and BCs, leading to more intermolecular interactions and better sealing for MMT. The calculated binding energies for interactions of BC with pre-adsorbed PPA on MMT were higher than those for interactions of BC with PPA alone. In both dry and wet laboratory conditions, bitumen modified with PPA-sealed MMT had higher values of shear thinning and G*/sin(δ) than bitumen modified with MMT.

Analysis of rheological properties and aging mechanism of bitumen after short-term and long-term aging

Bitumen aging is one of the main causes of pavement performance deterioration. It is of great significance to clarify the impacts of different aging degrees on bitumen performance, molecular composition, and components for the laboratory simulation of bitumen aging and the analysis of the aging mechanism. For this purpose, in this study, two types of virgin bitumen were selected, and the rolling thin-film oven test (RTFOT) and the pressure aging vessel (PAV) methods were employed for testing according to the following designs: RTFOT (85–385 min, interval 60 min), PAV (10–30 h, interval 5 h), and RTFOT + PAV (85 min RTFOT + 10–30 h PAV, interval 5 h). Dynamic shear rheological (DSR) and bending beam rheological (BBR) tests were used to study the high- and low-temperature rheological properties of bitumen under different aging conditions. Based on Fourier-transfer infrared (FT-IR) spectroscopy, gel permeation chromatography (GPC), and rod thin-layer chromatography with flame ionization detection (TLC-FID) tests, the effects of different aging conditions on the functional groups, molecular weights, and components of bitumen were analyzed to explore the aging mechanism of bitumen. The result showed that compared with the RTFOT + PAV and RTFOT aging modes, PAV aging had a weaker influence on the bitumen rheological properties. The RTFOT aging method had a greater impact on the sulfoxide index (SI), aromatic index (AI), and long-chain index (LCI) but a lesser effect on the carbonyl index (CI); however, the PAV aging method had a significant impact on CI. The RTFOT + PAV aging method had the greatest influence on CI, SI, AI, and LCI. Moreover, for the RTFOT and PAV aging modes, after aging for a certain period, the proportions of the large-molecular-size (LMS), medium-molecular-size (MMS), and small-molecular-size (SMS) components tended to be stable. In the RTFOT + PAV aging mode, with prolonged aging time, there was no obvious stable trend in the proportion of the three components. Compared with the RTFOT and PAV aging modes, the RTFOT + PAV aging mode had a greater impact on the number of bitumen molecules. Under RTFOT and PAV, the aged bitumen exhibited a decrease in aromatics, an increase in resins and asphaltenes, and a basically unchanged proportion of saturates. Under the RTFOT + PAV aging mode, the aromatics decreased, the resins and asphaltenes increased, and the saturates decreased. For bitumen aging, when the long-term aging test conditions are limited, the RTFOT aging test can be used instead; for example, RP20 can substitute R385.

Polyphosphoric Acid's synergy with bio-modified bituminous composites

Polyphosphoric acid (PPA) is among the most common modifiers used to increase bitumen's elasticity, improve bitumen's performance grade, and widen bitumen's operative temperature range. Recently, attention has been directed toward significant variations in PPA effectiveness when used in different bituminous composites. In other words, the same exact dosage of PPA affects various bitumens differently. The latter has been attributed to unexpected synergitic or antagonistic interplay between PPA and bitumen components. Considering the increasing use of bio-modifiers in asphalt industry, understanding such interplay is critical in design and engineering of bituminous composites. Here, we use the laboratory experiments and computational modeling, using density functional theory (DFT), to examine and compare the synergistic effects between PPA and each of five bio-modifiers (derived from wood pellet, miscanthus, castor oil, corn stover, or waste vegetable oil) to promote the durability and sustainability of bituminous composites while enhancing resource conservation and biowaste valorization. Based on the results, the bio-modifier made from wood pellets has the highest synergy with PPA (leading to the best dosage efficiency for PPA), followed by bio-modifiers made from miscanthus, castor oil, and corn stover. The bio-modifier made from waste vegetable oil shows the least synergy with PPA. The DFT results show the strong non-covalent interactions between PPA oligomers and the lignin units of the wood-based bio-modifier. In addition, due to the higher polarity of the wood-based bio-modifier compared to the bio-modifier from waste vegetable oil, a higher phosphorylation is expected to occur in the wood-based bio-modifier when exposed to PPA.

Modeling the hydrothermal impact on the Jurassic deposits of the West Siberian sedimentary basin (series with H2O and H2O2)

The results of hydrothermal modeling of the formation of epigenetic mineral associations and secondary reservoirs in various types of sedimentary rocks of the Jurassic age in Western Siberia in the H2O-H2O2 system are considered. The experiments were carried out at a temperature of 390°C, a pressure of 70 MPa and H2O2 concentrations varying from 0 to 37.5%. The duration of the experiments was 10 days. In all experiments, a pyrite mixture was added as a buffer. It was found that in experiments in which there was no H2O2, that is, the hydrothermal fluid consisted only of water, there was an intense formation of bitumen and volatile components from the organic matter present in the initial samples. The process of generation of bitumen and volatile components was accompanied by fluid fracturing of rocks and the formation of secondary porosity. Under these conditions, carbonates (calcite, siderite), plagioclases, and kaolinite turned out to be unstable. On the contrary, the formation of hydrothermal ferruginous chlorite was noted. Dissolution of unstable mineral phases by hydrothermal fluid led to the formation of additional secondary porosity. As the concentration of H2O2 and, accordingly, oxygen in the composition of the hydrothermal fluid increased, more and more complete oxidation of the organic matter present in the composition of the sediments was noted until its complete disappearance. With an increase in the oxygen concentration in the composition of the hydrothermal fluid, the appearance of first magnetite and then hematite, native sulfur, and anhydrite was observed. Under hydrothermal conditions with a maximum oxygen concentration, the formation of kaolinite and various sulfates in addition to anhydrite, represented by millosevichite, alum, as well as phases with the participation of elements that make up autoclaves, nickel and chromium sulfates, was noted. Intensive silicification of the sample surface is noted, as well as the constant presence of amorphous silica, which, along with various sulfates, is a quenching phase. These mineral phases are separated from the supersaturated hydrothermal fluid due to its rapid cooling and do not have time to form well-faceted crystals, but are present in the form of loose microporous aggregates. Along with kaolinite, the formation of hydrothermal film illite is noted. The results obtained indicate that the presence of bitumen in the Jurassic sediments is an important exploratory feature, indicating that in this place they were subjected to hydrothermal action, which means, firstly, secondary reservoirs with high filtration and capacity properties were formed, and second, there was an intensive generation of hydrocarbons and, as a consequence, the formation of hydrocarbon deposits.

Nondestructive Analysis of Mummification Balms in Ancient Egypt Based on EPR of Vanadyl and Organic Radical Markers of Bitumen.

The black matter employed in the funeral context by ancient Egyptians is a complex mixture of plant-based compounds with variable amounts of bitumen. Asphaltene, the most resistant component of bitumen, contains vanadyl porphyrins and carbonaceous radicals, which can be used as paramagnetic probes to investigate embalming materials without sample preparation. Electron paramagnetic resonance (EPR) at the X-band, combining in-phase and out-of-phase detection schemes, provides new information in a nondestructive way about the presence, the origin, and the evolution of bitumen in these complex materials. It is found that the relative EPR intensity of radicals and vanadyl porphyrins is sensitive to the origin of the bitumen. The presence of nonporphyrinic vanadyl complexes in historical samples is likely due to the complexation of VO2+ ions by carboxylic functions at the interface between bitumen and other biological components of the embalming matter. The absence of such oxygenated vanadyl complex in natural bitumen and in one case of historical human mummy acquired by a museum in the 19th century reveals a possible, nondocumented, ancient restoration of this mummy by pure bitumen. The linear correlation between in-phase and out-of-phase EPR intensities of radicals and vanadyl porphyrins in balms and in natural bitumen reveals a nanostructuration of radicals and vanadyl porphyrin complexes, which was not affected by the preparation of the balm. This points to the remarkable chemical stability of paramagnetic probes in historical bitumen in ancient Egypt.

Effect of waste plastic and crumb rubber on the thermal oxidative aging of modified bitumen

In this work, we study the contribution of crumb rubber (CR) and waste plastic (WP) to improve the thermal-oxidative bitumen aging resistance in short and long terms. All binders were exposed to short-term aging using RTFOT test (Rolling Thin Film Oven Test) and long-term aging using PAV test (Pressure Aging Vessel). The bitumen aging was characterised using physical and rheological tests such as penetration (Pen 25) at 25°C, ring and ball temperature and complex modulus. The degradation of bitumen components and polymer (waste plastic, crumb rubber) by thermal-oxidative aging was characterised using the FTIR spectra analysis. The physical and rheological results indicate that the modified binders are presented a good aging resistance than the pure bitumen. The WPmB presents the high resistance for the thermal-oxidative aging process comparatively to the pure bitumen and CRmB.

Extraction of Huadian oil shale in subcritical FeCl2 solution

The combination of subcritical water and catalyst was proposed for oil shale extraction. The extraction of Huadian oil shale in FeCl2 solution was performed at 350 °C to evaluate the combined method. At 20 h, a high yield of bitumen 1 (the bitumen discharged from shale matrix) was obtained in FeCl2 solution with an optimal concentration of 0.08 mol/L, which was 50.5% higher than that obtained in pure water. The bitumen 1 reached a maximum yield of 18.98 wt% at 40 h in subcritical FeCl2 solution and 19.14 wt% at 70 h in subcritical water, respectively. The time needed for a maximum yield of bitumen 1 was reduced by 43% after the addition of FeCl2. The results indicated that FeCl2 played an important role in the promotion of the cleavage of hetero-atomic bonds in kerogen and the transportation of bitumen 2 (the bitumen remaining in the shale matrix) in the shale matrix. It showed the addition of FeCl2 did not significantly affect the variation trends of the relative content of the major components in bitumen 1 and bitumen 2 with the time. The subcritical FeCl2 solution extraction should be a highly efficient method for in situ extraction of oil shale.

Organically treating montmorillonite with dual surfactants to modify bitumen

The contradiction between complex compositions of bitumen and the mono organic treatment on the montmorillonite (Mt) has not been fully considered during preparing bitumen-montmorillonite nanocomposite. In this study, dual surfactants, benzyl dimethyl stearyl ammonium chloride (S1) and octadearyl dimethyl ammonium chloride (S2), were adopted to treat the Mt together to increase its compatibility with bitumen. The structure of dual organically-treated Mt was characterized and its relation to the improvement of bitumen’s properties was studied. The results indicated that S1 surfactant containing the benzene ring with a larger volume increased the interlayer space of Mt more. After mixing with bitumen, the mono and dual organically-treated Mts had almost the same basal spacing. Based on the principle of the dissolution in a similar material structure, more oil components of bitumen entered the interlayer space of Mt when it contained more S2 surfactant, and more aromatic components of bitumen did this when more S1 surfactant. The bitumen modified by mono S2 treated Mt had better PAV ageing resistance due to the protection of the oily components of bitumen from volatilization. However, the bitumen modified by dual organically-treated Mt had better resistance to the UV ageing due to the reduction of oxidation, as well as of volatilization. Therefore, it was more useful to adopt the dual organically-treated Mt to modify bitumen, and consequently to improve the durability of asphalt pavement.

Effects of Steel-Slag Components on Interfacial-Reaction Characteristics of Permeable Steel-Slag-Bitumen Mixture.

In this paper, a permeable steel-slag–bitumen mixture (PSSBM) was first prepared according to the designed mixture ratio. Then, the interaction characteristics between steel slag and bitumen were studied. The chemical interaction between bitumen and steel slag was explored with a Fourier-transform infrared spectrometer (FT-IR). The influence of steel-slag chemistry, mineral composition, and bitumen reaction on phase angle, complex shear modulus (CSM), and rutting factor was explored with dynamic shear rheological (DSR) tests. The PSSBM had better properties, including high permeability, water stability, Marshall stability, high-temperature (HT) stability, and low volume-expansion rate. Bitumen-coated steel slag can prevent heavy-metal ions from leaching. In the infrared spectra of the mixture of a chemical component of steel slag (calcium oxide) and bitumen, a new absorption peak at 3645 cm−1 was ascribed to the SiO–H stretching vibration, indicating that new organic silicon compounds were produced in the chemical reaction between calcium oxide and bitumen. SiO–H had an obvious enhancement effect on the interfacial adhesion and high-temperature rheological property of the mixture. In the mineral components of steel slag, dicalcium and tricalcium silicate reacted with bitumen and generated new substances. Chemical reactions between tricalcium silicate and bitumen were significant and had obvious enhancement effects on interfacial adhesion and high-temperature rheological properties of the mixture. The results of FT-IR and DSR were basically consistent, which revealed the chemical-reaction mechanism between steel-slag microcomponents and bitumen at the interface. SEM results showed that pits and grooves on the surface of the steel-slag aggregate, and the textural characteristics provide a framework-like function, thus strengthening the strength and adhesion of the steel-slag–bitumen aggregate interface.

Karıştırma Koşullarının Polimer Modifiye Bitümün Özellikleri Üzerindeki Etkileri: Genel Bir Bakış

Modification of bitumen by different modifiers, causes the morphological, rheological and chemical characterisation differences related to the following three main factors: the type of the polymer, bitumen components and blending conditions. Manufacturing conditions can be investigated in several groups such as; mixing temperature, duration of mixing and shear rate (mixing speed). These manufacturing conditions are the key parameters, since they act an important role on the properties of the final product. These key parameters and their effects have always been an interesting topic for the researchers, because they may have some consequences like aging of the sample, degradation of the polymer or sometimes less absorption of the polymer by bitumen etc. This study aims to present the influences of mixing conditions on different properties of the bituminous mixtures with the help of reviewing the previous studies in the literature.

Negative impacts of environmental factors (UV radiation, water and different solutions) on bitumen and its mechanism

The environmental factors, such as the ultraviolet (UV) radiation, water, acid, alkali and salt, can cause significant negative impacts on the bitumen. Therefore, multi-factors coupling ageing test is closer to the actual service conditions of bitumen. Nine groups of coupling-condition ageing tests (UV radiation and the acidic, alkaline and neutral solutions) were conducted on the bitumen (Pen60/80). The conditioning times were 3, 6 and 9 days. After the test, the coupling hazards and its mechanism of these environmental factors on bitumen were analyzed. In detail, the transition of the appearance, physical and rheological properties of bitumen was characterized, the results show that coupled conditions have much more serious negative impacts on the performance of bitumen. In addition, to reveal the mechanism of negative impacts, the chemical functional groups and components of bitumen were studied, meanwhile the pH value, organic carbon content and chemical functional groups of the residual solutions were also analyzed, indicating that the coupled ageing mechanism mainly includes three channels, they are the excitation and break of bituminous molecules, the dissolution and leach of the organic component in the solutions, and the catalytic action of the alkali metal ions.

Materials Contamination and Indoor Air Pollution Caused by Tar Products and Fungicidal Impregnations: Intervention Research in 2014-2019.

Construction materials containing tar products are a source of indoor air pollution in buildings. This particularly concerns old buildings, in which wooden structures were impregnated with tar compositions (creosote oil and Xylamite oil containing tar products) and buildings in which bituminous seal containing hydrocarbon solvents was used. During the 1970s and 1980s, an impregnant known as Xylamite was commonly used in Polish buildings. This material still emits organic vapors into the building’s environment, significantly worsening indoor air quality (IAQ). Xylamites and other impregnating materials are a source of indoor air pollution through toxic organic compounds, such as phenol, cresols, naphthalenes, chlorophenols (CPs), and chloronaphthalenes (CNs), which emit specific odors. TD-GC/MS enables detailed identification of the reasons behind chemical indoor air pollution. The results of laboratory tests on the chemical emissions of bitumen-impregnated materials were presented in 32 case studies. In turn, the results of indoor air pollution by volatile bitumen components were presented on 11 reference rooms and 14 case studies, including residential buildings, office buildings, and others. Laboratory tests of samples of construction products confirmed the main emission sources into indoor air. The research results for the period 2014–2019 are tabulated and described in detail in this manuscript.

Studies of interaction between bitumen and thermochemical fluid (TCF): Insights from experiment and molecular dynamics simulations

Thermal enhanced oil recovery generally involves injection of steam into the reservoir or insitu heat propagation to reduce the viscosity of heavy oil. However, certain shortcomings, which are associated with steam injection, have paved way for finding an alternative method for insitu heat and pressure generation such as thermochemical fluid injection. The thermochemical fluid injection method offers several potential advantages including reduced heat loss, higher heat transfer efficiency, and negligible emission of CO2 compared to conventional steam injection. In this article, a deeper understanding of the process using the molecular dynamics simulations coupled with the experiment are presented. Guided by experimental information obtained from Saturates, Aromatics, Resin and Asphaltene fractions, total acid number, and density of bitumen sample, a molecular model of bitumen was built and validated. Subsequently, supported with the thermodynamic data obtained from the thermochemical reaction vis. enthalpy (ΔH) and order of reaction (n), Molecular dynamics simulations were used to examine the bitumen-thermochemical fluid interface, and the possible molecular interactions that could be involved between the bitumen matrix components and the thermochemical fluid. The thermochemical fluid reaction could generate sufficient temperature, typically, ≈170 °C and pressure ≈1600 Psi. The reaction was first order (n = 1) with ΔH = −370 KJ/mol, and the reaction Ea ≈ 35.5 kJ mol−1. Ultimately, molecular dynamics simulations gave detailed insights into the molecular interactions that could be established at the bitumen-thermochemical fluid interface. Our results put in evidence the changes of bitumen matrix upon the injection of thermochemical fluid. Indeed, molecular dynamics results show that the insitu heat released from the thermochemical reactions induces a homogeneous texture of the bitumen matrix via disturbing the large aggregates of the heavy bitumen components such asphaltene, and resin. The formation of salt resulted in a stronger interaction of salt-acids type between the two phases, which leads to further stabilization of the water-phase inside the bitumen matrix and prevent its collapse. Furthermore, the insitu formation of N2 gas and its diffusion through bitumen matrix softens its texture and lead to disturbing of the tight interaction between the bitumen matrix components. As, the temperature increases the kinetic energy of N2 gas increases and make it more efficient to decrease its viscosity and hence its mobility. This phenomenon has also been corroborated through the thermogravimetric analysis and the scanning electron microscopy, which revealed improved thermal decomposition performance due to reactivity and/or interfacial interactions between thermochemical fluid and bitumen matrix.