Bitumen Samples Research Articles

Solid bitumen as an indicator of petroleum migration, thermal maturity, and contact metamorphism: A case study in the Barrandian Basin (Silurian - Devonian), Czech Republic

Silurian and Devonian marine shales and limestones of the Barrandian Basin host abundant black solid, non-fluorescing bitumens that fill tectonic fractures and veins, and occlude fossil moulds and diagenetic concretions. Solid bitumen, interpreted as thermally degraded petroleum, entered the rocks during several successive episodes of fracture-bound petroleum migration that occurred during deeper burial of the strata. Regional distribution of bitumen reflectance values that range between ∼0.9–2.3% Rr, correlate with variations of its FT-IR and Raman spectroscopic characteristics and aromatic hydrocarbon composition, and collectively evidence the maturity trend increasing across the basin from the southwest to the northeast. The reflectance of chitinozoans and graptolites (∼0.8–1.9% Rr) in the country rocks and homogenization temperatures of hydrocarbon fluid inclusions document palaeotemperatures ranging between ∼90–150 °C, characteristic of the oil window zone grading into the gas/condensate zone. Although in a basin-wide perspective the averaged values of solid bitumen and zooclast optical reflectance converge and indicate the same northeastern-increasing regional diagenetic trend, solid bitumen reflectance values vary considerably at individual localities and even within some bitumen samples. The wide scatter of optical reflectance values and the heterogeneity of optical properties, which were attributed to the presence of multiple source rocks in the basin, the variable lithology of bitumen host rocks, or other variables, hamper the use of solid bitumen as a simple alternative to zooclast/vitrinite reflectance palaeothermometers in a given basin. On the other hand, the highly anisotropic domain and the mesophase “coking” textures of the solid bitumen that were recognized in the NE part of the basin provide unique evidence on an anomalous, hitherto unrecognized, geologically short-lasting thermal event that affected the Palaeozoic rocks. A line of indirect evidence suggests that the coking of the bitumen was caused by a cryptic intrusion, possibly a concealed branch of the Central Bohemian Pluton, which intruded into the strata during the Variscan orogeny. More rarely occurring semi-solid, vividly yellow fluorescing waxy bitumen, that postdates solid bitumen in some fractures and voids, does not reveal a regional thermal maturation trend. It precipitated from relict waxy oils that migrated through the strata during a post-Neogene uplift of the Barrandian region.

COMPOSITION OF BROMIDES FORMED UPON SELECTIVE CLEAVAGE OF ETHER/ESTER BRIDGES IN PETROLEUM AND NATURAL BITUMEN OILS

Gas chromatography with mass spectrometric detection (GC-MS) was used to study the composition of bromides obtained upon selective cleavage (chemolysis) of the C-O bond of ether/ester bridges under the action of BBr3 in oil components from ten oil and natural bitumen samples. It is shown that most of the samples under study demonstrate the absence of mono- and dibromides of alkanes, alkylcyclohexanes, pregnanes and steranes, cheilanthanes and hopanes in the products of chemolysis. Monobromides of n-alkanes have been identified only in the products of chemolysis of oil components isolated from maltha of the Ashalchinskoye oilfield and the products of its biodegradation under laboratory conditions. In total, the identified products of selective cleavage of ether/ester bridges include mono- and dibromides of alkylbenzenes: mainly (С13-С22)-alkyltrimethylbenzenes, (С1-С7)-naphthalenes, phenanthrene, dibenzothiophene and their homologues. Monobromides of C6-biphenyl, C4-tetralin, dibromides of (C2-C6)-benzothiophenes, (C2-C5)-biphenyls, C1-tetralin, fluorene, and C2-fluorene have been also identified. Tribromides of (С2-С4)-naphthalenes, С2-phenanthrene, and (С1-С2)-fluorenes have been identified in a limited number of samples. In chemolysis products, dibromides occur more rarely than monobromides, while tribromides are much less common than dibromides. The results obtained indicate that the above-mentioned compounds are partially present in oils as structural fragments connected with other fragments of the oil components through one or much less often through two or three ether/ester bridges. The list of structural fragments linked via ether/ester bridges, their composition and relative content differ in oil components of different oil and natural bitumen samples. Ethyl esters of aliphatic acids from C12 to C32, with a clear predominance of even acids and a maximum corresponding to C16 and C18, have been identified in the products of chemolysis of almost all samples.

ASPHALT BINDERS EMPLOY VARIOUS ORGANIC ADDITIVES: PHYSICAL AND RHEOLOGICAL QUALITIE

Several studies aim to reduce surface temperatures and improve the performance of hot mix asphalt. These studies have occurred to reduce the global warming phenomena and economic concerns. We're researching how organic materials affect the viscosity of modified asphalt. Asphaltan A, Asphaltan B, Asphaltan C, and T-grade are organic additives. temperatures with the asphalt binder were employed in the current study. These organic additives were used to improve the characteristics of hot-mix asphalt. In addition, it increases the durability, and lifespan of pavement and reduces mixing and compaction temperatures. A penetration grade bitumen of 40/50 was used in this study. Then, pure bitumen was added to the organic additives to modify binders containing varying concentrations of each additive. Physical properties were performance at different levels of additives. In the research, conventional bitumen/asphalt should be adjusted due to climate conditions, strong traffic loads, and growing axial loads. As a result, asphalt mixtures comprehending bitumen with a high penetration index are less prone to low-temperature cracking and irreversible deformation. Traditional asphalt studies found that bitumen samples with the softening point of warm mix asphalt additives were greater rate, and were less susceptible to temperature changes. The introduction of organic compounds increased the penetration and softening point of the asphalt substantially. This indicated that the stiffness and thermal expansion of the binder had gotten better.

Dynamic-Mechanic Analysis and Rheological Modelling of Waste Face Mask Modified Bitumen

Due to the Covid-19 global pandemic, the use of face masks has increased considerably in recent years. Used face masks are released into our environment and become a severe environmental threat. Therefore, researchers have focused on the recycling of waste face masks. Recently, studies have been carried out on the use of waste face masks as additives in bituminous materials, but a detailed rheological characterization has not been made. In this study, modified bitumens were obtained by adding 1%, 1.5%, 2%, 2.5%, and 3% waste face mask (WFM). Subsequently, frequency sweep test was performed on modified bitumen samples through a Dynamic Shear Rheometer (DSR). Thus, the viscoelastic behavior of WFM modified bitumen was investigated at different temperatures and loading rates. Performance analysis was conducted with rheological master curves, which were characterized according to analytical and mechanistic models. In this study, rheological evaluations were performed according to the Christensen-Anderson (CA) Model, Christensen-Anderson-Marasteanu (CAM) Model, Sigmoidal Model (SM), and finally, the mechanistic Huet-Sayegh Model (HSM). According to the results, it was determined that WFM significantly increased the rutting resistance of bitumen and performed better at low and high loading rates than the pure bitumen at each WFM ratio.

Optimization of Bio Asphalt Derived from Pyrolysis Bio Oil for Bitumen Modification

Due to inadequate crude oil supply and a rising demand for petroleum asphalt in roadconstruction, the asphalt sector faces a continuing shortage. Continous research was conducted on renewable materials such as bio-oils derived via pyrolysis from local palm oil industries. Bio-oil is currently a viable option due to its renewability, environmental friendliness, and variety of sources. Despite numerous studies indicating that biooils enhance the properties of bitumen, the research on the effects of PKS biooil on bitumen properties is minimal and needed further investigations. The application of 2,4-diphenylmethane diisocyanate (MDI) in this study is established to enhance the properties of bio-oil modified bitumen. The objectives of this study are to analyse the relationship between the percentage andratio of PKS bio-oil and 2,4-diphenylmethane diisocyanate (MDI) of the modified bitumen, its physical and chemical effects and the optimization of bio-asphalt mixture after the 2,4diphenylmethane diisocyanate (MDI) has been blended with PKS bio-oil and bitumen. PKS bio-oil and MDI were applied into the bitumen as additive and replacement of bitumen at 3%, 5% and 7% with two different ratios; 1.0:0.6 and 1.0:1.0. The functional groups of the bitumen are identified using Fourier Transform Infrared (FTIR) analysis. The result generated from FTIR analysis showed that the modified bitumen samples were slightly different when compared to the conventional bitumen regarding the functional group. Response surface methodology (RSM)was implemented to determine the statistical analysis and optimum amount of PKS bio-oil and MDI content in the bitumen, through central composite design.

Geochemical characteristics of Cambrian bitumen and Cambrian-Ordovician source rocks in the Keping area, NW Tarim Basin

The Cambrian Yuertus Formation and Ordovician Saergan and Yingan formation source rocks, which TOC contents of 0.38%–4.30%, are well developed in the Keping area of the Tarim Basin. Reservoir bitumen had been found in the Cambrian Wusongger Formation and Shayilike Formation. In this study, the geochemical characteristics of the bitumen and source rocks were analyzed through biomarkers for oil-source correlation. The results show that the characteristics of the bitumen and Yuertus Formation source rocks are similar. Comparatively, the Yuertus Formation source rocks and bitumen have lower Pr/Ph values and higher C28/C29 regular steranes values. The maturity characteristics and depositional environment of the Cambrian source rocks in the Keping area and the platform basin areas are similar. Plots of Ph/n-C18versus Pr/n-C17, Ts/(Ts+Tm) versus 4-/1-MDBT (methyl dibenzothiophene), and DBT/P (dibenzothiophene/phenanthrene) versus Pr/Ph distinguish the bitumen and source rocks well. As an original plot, we found that the Fla/Py (fluoranthene/pyrene) versus MP/P (methyl-phenanthrene/phenanthrene) intersection plot can be used to identify the possible sources of polycyclic aromatic hydrocarbons (PAHs) to a certain extent and can distinguish between the Cambrian and Ordovician source rocks in this study. Comprehensive analysis revealed that the bitumen samples most likely originated from the Yuertus Formation source rocks. It was also found that the biomarker characteristics such as the shape type of the C27-C28-C29 regular steranes, triarylosteranes, and triarylosteroids are not applicable to distinguishing the Cambrian and Ordovician source rocks in the Keping area. These research findings provide references for studying the Lower Paleozoic oil-source correlation in the platform in the Tarim Basin.

Bitumen stress relaxation modulus and its slope as performance-based criteria to control low temperature cracking

ABSTRACT This paper aims to determine the performance-based criteria for bitumen to control low temperature cracking in asphalt pavements. For this purpose, the performance of 26 recovered bitumen samples was analysed using the dynamic shear rheometer with 4-mm parallel plates (4-mm DSR). The stress relaxation modulus and its slope at 60 s were determined by performing a stress relaxation test at specific critical temperatures. The changes in these properties depending on the test temperature were analysed. The stress relaxation modulus and its slope at 60 s of 26 recovered bitumen samples were compared with the actual performance of the road sections from which these bitumen samples were recovered. On the basis of that, the limiting values of the stress relaxation modulus and its slope at 60 s were determined. The research showed that the formation and development of low temperature cracks on asphalt pavements are limited, when the stress relaxation modulus and its slope at 60 s and at temperature 10°C higher than the lowest asphalt surface temperature are not higher than 52 MPa and not lower than 0.370, respectively. These performance-based criteria are incorporated into the algorithm developed to assess bitumen resistance to low temperature cracking.

How infrared and fluorescence spectroscopy can shed new light on the characterization of bitumen and its ageing processes

A combination of chromatography and spectroscopy was applied to characterize the chemical peculiarities of bitumen and analyse thermally induced ageing processes. Therefore, a bitumen sample was short-term and long-term aged followed by a polarity-based fractionation. Subsequently, the fractions and the base binder were analysed by infrared (IR) and fluorescence spectroscopy. IR provided the possibility to track the fate of carboxylic acids and quinolones and the evolution of ketones and sulfoxides during oxidative ageing. Information on abundant aromatic structures and the effect of ageing on certain molecular classes was obtained with fluorescence spectroscopy. It was shown that shifts to higher emission wavelengths correlate to the polarity of the fractions and the ageing state. Solid-state measurements of the resins revealed characteristic signals of porphyrins and how they are affected during ageing. Here we evaluate the impact of different ageing conditions with the perspective to improve the understanding of complex chemical ageing in bitumen.

Characterization of long-term aged bitumen with FTIR spectroscopy and multivariate analysis methods

One of the most common techniques used to investigate bitumen aging from a chemical perspective is Fourier-Transformation Infrared (FTIR) spectroscopy. However, the majority of standard spectral interpretation simply covers the observation of single bands associated with carbonyls, sulfoxides or aromatic structures. A possibility for a more comprehensive post-processing of FTIR data is to apply multivariate analysis (MVA) methods. Although, MVA methods have already been used for classifying differently aged bitumen in the past, the deployed methods only included standard laboratory aging and failed to consider factors like reactive oxygen species or light. The purpose of this study was the investigation of aged bitumen samples with FTIR spectroscopy and subsequent data processing with MVA. Therefore, nine bituminous binders were subjected to aging with the Pressure Aging Vessel (PAV), Viennese Binder Aging (VBA) and light, followed by a characterization with FTIR spectroscopy and various MVA methods. It was possible to investigate the general structure of the acquired data and differentiate between the aging methods solely based on FTIR spectra. Furthermore, important wavenumbers for the classification were identified, including spectral features around the wavenumbers 3371, 3027, 2943, 1550 and 1324 and 848 cm−1 for the original spectra. This study shows the potential of MVA to maximize the information content gained by experimental analysis and for the development of fast and easy characterization methods.

Geochemical characteristics of bitumen seeps from the pila spi and bekhme formations: insights from fourier transform infrared spectroscopy and trace metals

A collection of 9 bitumen samples from Pila Spi Formation (Middle–Late Eocene) and Bekhme Formation (Late Campanian – Early Maastrichtian) were subjected for geochemical analysis of Fourier Transform Infrared Spectroscopy (FTIR) and trace metals. The results of FTIR analysis reveal the different intensity for the samples of both formations. The broad band centered around 1500–2000 cm−1 which is indicative of the presence of C=O Stretch band and C=C Stretch might be assigned to a carbonyl stretching. The Frequency of the bitumen - derived asphaltene samples of the Gulley Keer indicate the presence of Carboxylic acids, while no band appeared for Bekhme samples which indicates the absence of Carboxylic acid. The peak absorption bands of the analyzed samples at 1452, 2802, 2905, and 3050cm−1 can be due to C-H bending, Alkyl C-H stretch, and Alkenyl C-H stretching respectively. Based on the Aromatic, Aliphatic and long chain indices as well as the ratio of Nickle to Vanadium, two different sources of the organic matter are suggested for analyzed samples. Moreover, all samples from both sections are believed to be from a marine euxinic carbonate environment with the exception of one sample that seems to be marine anoxic- shale- carbonate.

Investigation of Physical and Chemical Properties of Bitumen Modified with Waste Vegetable Oil and Waste Agricultural Ash for Use in Flexible Pavements

The rapid growth of the world population and the rapid diversification of consumption habits due to technological advancements have increased waste production. An investigation of the effects of biomass products, such as waste vegetable oil and waste agricultural ash, on bitumen’s physical and chemical properties was conducted in this study. By recycling biomass products, this study aimed to improve the performance and stability of bituminous hot mixtures, optimize the number of additives, and create more economical designs. Using the Taguchi method, 0%, 2%, 4% by weight of waste vegetable oil and 0%, 3%, and 6% by weight of waste agricultural ash were added to 70/100 penetration pure bitumen with an orthogonal array of L9. For 10, 20, and 30 min, modified bitumen samples were prepared at 170 °C, 180 °C, and 190 °C with a constant mixing speed of 3000 RPM. The samples were tested for penetration, softening point, flash point, rolling thin film oven (RTFOT), FTIR, and Marshall Design stability and flow. Based on the obtained performance statistics, 95% confidence levels were assigned to the predictions. The stability and softening point values decreased as the oil content increased, while flash and penetration values increased. With increasing ash content, stability, flash, and softening point values increased, and penetration values decreased. Compared to oil and ash additives, mixing temperature and time had relatively little effect on the modification process. Overall, the optimum parameter levels were 4% for oil, 0% for ash, 170 °C for temperature, and 10 min for time.

Influence of physical properties and chemical compositions of bitumen on foam characteristics

This study explores the influence of intrinsic bitumen properties on foam characteristics, considering physical properties (penetration, softening point, viscosity), chemical compositions (SARA components, FTIR indices), and physico-chemical characteristics [surface free energy (SFE)]. Ten distinct bitumen samples from two different sources were analyzed. The results reveal that physical properties alone do not sufficiently account for variations in foaming potential among bitumen types. However, chemical compositions and SFE proved to be more informative, explaining the differences in maximum expansion ratio and foam index, specifically for bitumen from the same source. In contrast, when bitumen originates from different sources, none of these intrinsic properties can clarify foaming potential. Notably, intrinsic bitumen properties fail to elucidate the variability in the half-life of foamed bitumen, even when the bitumen types share the same source. These findings underscore the significance of considering multiple factors when assessing bitumen's foam characteristics, particularly when evaluating materials from diverse sources.

A novel method to improve anti-aging properties of SBS modified bitumen by zinc oxide/expanded vermiculite composite: Influence of zinc oxide particle loadings

Styrene-butadiene-styrene copolymer modified bitumen (SBSMB) has been commonly used in pavement construction for its excellent performance. However, during construction and service life, SBSMB is inevitably subjected to thermal-oxidative or ultraviolet aging as a result of factors in the environment like heat, light and oxygen. This study investigated the effects of zinc oxide/expanded vermiculite composite (Z/E) on SBSMB, in particular the effects of Z/E with different zinc oxide (ZnO) particle loadings on SBSMB. And Z/E with different ZnO particle loadings were prepared and characterized by X-ray fluorescence spectrometer, field emission scanning electron microscope, UV–Visible spectrometer and Fourier transform infrared spectrometer tests. To age bitumen samples, thin film oven test, pressure aging vessel and ultraviolet aging tests were used. Eventually, the effects of Z/E with various ZnO particle loadings on the storage stability, physical, rheological and anti-aging properties of SBSMB were investigated. According to the results, Z/E with different ZnO particle loadings are successfully prepared. There are uniform ZnO particles on the surface of expanded vermiculite and ZnO particle loadings are increased with the concentration of the ZnO precursor solution. Furthermore, the high-temperature performance of SBSMB is enhanced, but the low-temperature performance is slightly affected by Z/E. Whatever the aging mode, the introduction of Z/E can obviously reduce the viscosity aging index, softening point increment, complex modulus aging index and increase phase angle aging index of SBSMB, demonstrating that the aging resistance of SBSMB are significantly enhanced. It was determined that SBSMB with 29.5 wt%Z/E had the best aging resistance.

Probing the surface forces between air bubbles and bitumen via direct force Measurements: Effects of aqueous chemistry

The surface interactions of air bubbles and other components (e.g., particles, oil droplets) significantly influence the operation efficiency of a variety of engineering processes such as oily water treatment, bitumen extraction and flotation. Herein, the surface interactions of air bubbles with two types of Athabasca bitumen samples in aqueous solutions of varying pH, salinity, type of cations and in the presence of surfactants have been systematically characterized using a bubble probe atomic force microscope (AFM) technique. AFM imaging has revealed that exposure to high concentrations of NaCl and CaCl2 solutions or alkaline environments causes roughening of the bitumen surfaces. The results of surface force measurements demonstrate that the interaction and attachment behaviors between bubbles and bitumen are significantly affected by ionic strength, solution pH, and the presence of surfactants. The experimental force measurement results could be accurately described by a theoretical model that incorporates Reynolds lubrication theory and augmented Young-Laplace equation, with the inclusion of disjoining pressure. In low-salinity conditions, the bubble-bitumen interaction is dominated by electric double layer (EDL) repulsion, which prevents surface attachment. This effect is more pronounced at elevated pH conditions. In high-salinity solutions, however, the EDL interactions are significantly reduced, and the hydrophobic interaction becomes the dominant factor, overcoming the van der Waals repulsion and leading to the attachment of bubbles to bitumen surfaces. Raising aqueous pH weakens the bubble-bitumen hydrophobic interaction, whereas the introduction of calcium ions strengthens this interaction, resulting in enhanced surface attachment. Interestingly, even in high-salinity conditions, the presence of a small number of surfactants can inhibit bubble-bitumen contact, mainly caused by reduced hydrophobic attraction and increased steric repulsion. This work provides valuable nanoscale insights into how bubbles and bitumen interact in intricate aqueous environments, and the results show practical implications for controlling similar interfacial phenomena in various engineering processes.

High-levels of toxic elements and radioactivity in an abandoned sulphur mine: Insights on the origin and associated environmental concerns

Natural fibrous epsomite crystals containing high amounts of toxic and radioactive elements have recently been discovered in the abandoned sulphur mine of Perticara (Italy). In the present study, all the different matrices that characterize the Perticara mine (air, water, host-rock, minerals, and bitumen) were sampled and investigated employing a multi-analytical approach to define the distribution and origin of these hazardous elements. Water samples showed high Al, Fe, Pb, Mg, and Mn content but not radioactive elements. The bitumen sample showed a higher amount of 210Po and 210Pb (0.12 Bq/g and 0.11 Bq/g, respectively), compared to the host-rock and fibrous sericolite samples, but lower than fibrous epsomite crystals (210Po 5.59 Bq/g; 210Pb 5.93 Bq/g). A high 222Rn concentration was also detected in the tunnels and it is likely the source of both 210Po and 210Pb, which are in radioactive equilibrium, especially in epsomite. This latter mineral, being capable of capturing 210Po and 210Pb, can be used as a helpful mineral indicator for the presence of radioactive elements in similar environmental conditions. Moreover, our results also highlight a slight anomaly in the 40K and 226Ra content of the host-rock, probably derived from the evaporitic sediments of the rock succession. The current risk for humans linked to the mine environment is minor since the activity of the mine ended several decades ago. However, the results of this study must be taken into serious consideration for any future development of this area (e.g., industrial archaeology, farming, educational, scientific and touristic purposes), and represent the basis for the calculation of radiotoxicity and dose assessment, which is fundamental for the correct and safe management of the mining environment and neighbouring areas.

Insights on In Situ Combustion Modeling Based on a Ramped Temperature Oxidation Experiment for Oil Sand Bitumen

The ramped temperature oxidation (RTO) test is a screening method used to assess the stability of a reservoir for air-injection Enhanced Oil Recovery (EOR) and to evaluate the oxidation behavior of oil samples. It provides valuable kinetic data for specific cases. The RTO test allows for the analysis of various characteristics, such as temperature evolution, peak temperatures, oxygen uptake, carbon dioxide generation, oxidation and combustion front velocity, recovered and burned hydrocarbons, and residual coke. The adaptation of RTO experiments to in situ combustion (ISC) modeling involves validation and history matching based on numerical simulation of RTO tests, using 3D digital models of experimental setup. The objective is to estimate the kinetic parameters for a customized reaction model that accurately represents ISC. Within this research, the RTO test was provided for bitumen samples related to the Samara oil region. A 3D digital model of the RTO test is constructed using CMG STARS, a thermal hydrodynamic simulator. The model is designed with multiple layers and appropriate heating regimes to account for uncertainties in the experimental setup and to validate the numerical model. The insulation of the setup affects radial heat transfers and helps to control the observed temperature levels. The modified traditional reaction model incorporates thermal cracking of Asphaltenes, low-temperature oxidation (LTO) of Asphaltenes and Maltenes, and high-temperature combustion of coke. Additionally, the model incorporates high-temperature combustion of light oil in the vapor phase, which is generated through Asphaltenes cracking and LTO reactions.

Laboratory evaluation of the effect of waste materials on mechanical properties of asphalt binder and mixture containing combined natural binder and waste polymer

The current study's objective is to examine the characteristics of waste polymer-incorporated natural binder modified binders and combinations. Recycling and making use of waste polymers has gained interest as a possible environmentally and financially responsible bitumen modification method. The goal of the current study was to explore the rheological and mechanical characteristics of mixes and bitumens modified with natural binder that contained various amounts of waste polymer. Original bitumen modified with 5%, 10%, and 15% weight of asphalt binder as well as varied amounts of RPW (3%, 5%, and 7% weight), were all employed as samples of bitumen in the study. Several asphalt binder tests such as conventional tests and rheological ones were performed on binder samples. The results showed that adding waste polymer to the natural binder modified binders enhanced their high-performance temperature, as seen by the decreased penetration and increased softening point values. Results revealed that binders containing 5%, 10% and 15% gilsonite have fatigue life at 2.5% strain about 1.06, 9, and 9.8 times higher than original binder, respectively. Results revealed that addition of 5%, 10% and 15% gilsonite leads to decrease the Jnr value by 36%, 87%, and 96%, respectively. While addition of 3%, 5%, and 7% RPW leads to increase the fatigue life by 1.12, 3.75, 5 times higher than 5% gilsonite modified asphalt. Additionally, the binders treated with waste polymers performed better at low temperatures as seen by their decreased stiffness and enhanced fracture resistance. However, a substantial proportion of waste polymer caused both low and high temperature performance to decline. Overall, this study indicates that waste polymer has the ability to enhance the performance characteristics of naturally occurring binder modified binders, but it is important to carefully evaluate the ideal waste polymer percentage in order to obtain the required performance advantages.

The Effect of Wetfix and Nanohydrated Lime Additives on Bitumen Aging and the Cohesion and Adhesion Failure Mechanisms of Hot Asphalt Mixtures

Aging due to sunlight and the passage of time is an effective element in the occurrence of moisture damage in hot asphalt mixtures. Still, the effects of this parameter are scarcely considered in the experiments examining the moisture damage potential. Accordingly, this study investigated the effect of aging on the performance of hot asphalt mixtures and examined the improvement of moisture damage performance by using antistripping additives via mechanism and functional tests. Two types of aggregates (limestone and granite) with different degrees of moisture sensitivity, two types of bitumen (PG64-16 and PG58-22) with different performances, and two additives (Wetfix liquid additive and nanohydrated lime) as bitumen modifiers were used. Bitumen samples and asphalt mixtures were subjected to short- and long-term aging. The pull-off test was performed to explore the aging effect on different failure mechanisms (cohesion and adhesion), and the indirect tensile stiffness modulus (ITSM) test was conducted to study the asphalt mixture’s performance against moisture damage. The results specify that aging, in terms of hot asphalt mixture hardening in dry and wet conditions, decreased the MSR (resilient modulus wet to resilient modulus dry ratio), and this decline was greater in long-term aging. The pull-off test results exhibited that aging, especially in the long term, decreased the asphalt mixture’s adhesive strength in dry and wet conditions; this decline in adhesion was greater in the wet than in the dry state, and this difference decreased the wet-to-dry adhesion strength ratio (the pull-off ratio). The additives relatively improved the yield modulus of the asphalt mixture, but their effect was greater in the wet state. A comparison of the pull-off test results in cohesion and adhesion failure demonstrated that Wetfix was more effective in improving bitumen–aggregate adhesion, whereas nanohydrated lime was more effective in enhancing bitumen adhesion. The resilient modulus (Mr) ratio in wet-to-dry conditions indicated that nanohydrated lime had better effects on the overall performance of the aged asphalt mixture against moisture damage. To investigate the effect of additives on the performance of asphalt mixtures, a t-test was performed in all modes of control, short-term aging, and long-term aging. The findings showed the effect of Wetfix and nanohydrated lime on increasing the modulus of elasticity of the samples.

N-Alkane bound biomarker fingerprints from asphaltenes in the bitumens of Eastern Dahomey Basin, Nigeria: Source and genetic implications

The asphaltene fractions of the bitumens of Eastern Dahomey Basin in Nigeria, were analyzed by flash pyrolysis-gas chromatography (Py-GC) method in order to unravel its geochemical history and properties. The distributions of the initial biomarkers of the original oils from the pyrolysates are related to the assessment of organic matter source, paleo-redox conditions and source environment during deposition. Also, it effectively establishes the genetic relationship of the bitumens. The n-alkane distributions in the pyrolysates reveal nC9-nC32n-alkanes, maximizing at nC14, isoprenoids-pristane (Pr) and phytane (Ph), and some n-alkene peaks. High peaks of low to medium-weight nC9-nC20n-alkanes and low peaks of nC21+n-alkanes characterize the distributions. These reveal that abundant algal organic matter with some terrigenous inputs contributed to the source rock of the bitumens. The high concentration of marine organic matter inputs to the source rock is further confirmed by the nC17/nC27 ratios which range from 5.39 to 19.82 and shows the predominance of nC17 alkanes. The general unimodal n-alkane distributions in the bitumens indicate derivation from similar organic matter types showing that they are genetically related. The anoxic to suboxic environmental conditions that prevailed during the deposition of the sediments is revealed by the isoprenoids, Pr/Ph ratios (0.72–1.28). Pristane/nC17 and Phytane/nC18 range from 0.16 to 0.33 and 0.22 to 0.56, revealing that the bitumens were from predominantly marine organic matter (type II kerogen) preserved in a reducing environment with no evidence of biodegradation. However, the Ph/nC18 ratio and the cross plot of Pr+Ph/nC17+nC18 allow the classification of the bitumens into two subfamilies/groups (A and B). The bitumen samples have low wax content as indicated by the degree of waxiness ranging from 0.21 to 0.38 which confirms low terrigenous input. Based on the carbon preference index (CPI: 0.92 to 1.55) and odd-even predominance (OEP: 0.70 to 1.36), it is concluded that the bitumens are immature to marginally mature.

Interfacial bonding property and microscopic damage mechanism of bitumen-aggregate in salt-freeze-thawing environment

Deicing salt or snow-melting agent has a corrosive effect on the pavement, which reduces the durability of asphalt pavement. The interfacial bonding properties of bitumen-aggregate is one of the main factors affecting the durability of asphalt mixture. To evaluate the interfacial bonding properties of bitumen-aggregate and reveal the damage mechanism under salt-freeze-thaw coupling effect, the bitumen-aggregate samples with the same film thickness were formed by controlling the applied load. The corrosion of deicing salt on bitumen-aggregate and bitumen film samples was simulated by freeze-thaw cycles in 1 %, 3 % and 5 % NaCl solution. The pull-off test of SBS modified bitumen-aggregate after salt-freeze-thaw cycles was conducted. The Fourier transform infrared spectrometer (FTIR) test was carried out to qualitatively and quantitatively analyze the impact of salt-freeze-thaw coupling effect on bitumen functional groups. The surface morphology of bitumen samples treated in salt-freeze-thawing environment was also scanned by atomic force microscopy (AFM) in tapping mode. The results illustrate that the pull-off strength of bitumen-aggregate decreases sharply first and then the decrease rate slows down with the rise of salt-freeze-thaw coupling cycles. The carbonyl index and sulfoxide index of SBS modified bitumen increases, and the butadiene index decreases after freeze-thaw cycles in NaCl solution. The environment of salt erosion and freeze-thaw cycle accelerates the deterioration of SBS modifier and reduces the distinction of various phases in bitumen binder. Then the Ra and Rq of SBS modified bitumen decreases significantly in salt-freeze-thawing environment. The decrease of butadiene index and root mean square roughness leads to the weakening of adsorption between SBS modified bitumen and aggregate, which is the main reason for the damage of interfacial bonding performance of bitumen-aggregate. In summary, the salt-freeze-thawing environment damages the bonding performance of bitumen-aggregate. The damage law and deterioration mechanism of bonding properties of bitumen-aggregate presented in this paper provides some references for the optimal design of asphalt mixture in salt-freeze-thawing environment.