Rheological Behavior Of Bitumen Research Articles

Antiaging Effects of Linear Alkyl Benzene Sulfonic Acid Utilization on Bitumen Modification

The manufacture of asphalt pavements causes various environmental problems due to bitumen’s hazardous nature. Aging of bitumen yields undesirable properties, which may cause several adverse effects on asphalt performance. Use of antiaging agents for bitumen modification results in improved aging resistance, hence such agents confer environmental benefits by reducing the consumption of bitumen owing to lower maintenance requirements and the reduced volume that needs to be produced. Therefore, it is important to develop new antiaging agents and investigate their benefits to the asphalt industry. This study investigated the use of different rates (1%, 2%, and 3%) of linear alkyl benzene sulfonic acid (LABSA) as a bitumen antiaging agent through chemical and rheological characterization on unaged, short-term-aged, and long-term-aged samples using Fourier transform infrared spectroscopy and dynamic shear rheometer (DSR). A chemical aging index (CAI) and various rheological aging indexes, obtained by the construction of master curves and crossover temperatures were calculated to evaluate the variation of aging effects by LABSA addition. The detailed experiments showed that LABSA-modified samples exhibited better aging resistance compared to neat (base) bitumen. Additionally, the statistical analyses of all aging indexes were investigated to obtain the relationship between chemical and rheological aging indexes. The determination coefficient (R2) and scatter index (SI) results showed that the rheological behavior of bitumen against aging could be evaluated based on chemical behavior and vice versa. Moreover, it was concluded that short-term aging and long-term aging effects should be evaluated separately to determine the relationship between different aging characteristics of samples.

Effects of copolymers on rheological and performance of binders and stone matrix asphalt mixtures

ABSTRACT This research examines the effect of Nano-high density polyethylene (NHDPE) and SBR (Styrene–Butadiene Rubber) additives on the binders and stone matrix asphalt (SMA) mixtures’ performance behaviours. AC-60/70 binder, NHDPE (0%, 2%, and 4% by weight of binder), and styrene butadiene rubber (SBR) (0%, 2%, and 4%, by weight of bitumen) are utilised. Besides, the impact of the combination of SBR (1% and 3%) with NHDPE (1% and 3%) on the rheological behaviour of bitumen and the mechanical properties of the mixture was assessed. The results of the experimental tests were statistically evaluated using a two-factor analysis of variance (ANOVA). According to the rheological behaviour test, using both SBR and NHDPE additives not only enhance binders’ rutting and fatigue resistance as well as phase separation but also decrease binders’ low-temperature resistance. Besides, adding SBR, NHDPE, and NHDPE/SBR enhances the fatigue and rutting resistance of binders. The utilisation of both SBR and NHDPE increases the permanent deformation resistance, MR, ITS, fracture energy, and fatigue properties of a specimen. It was also found that NHDPE in comparison with SBR has a better impact in enhancing the performance of the mixture.

Effect of asphaltene on the rheological properties of bitumen

In this paper, the rheological behavior of bitumen as a function of asphaltene concentration has been studied. Several bitumen samples having distinctly different amounts of asphaltene were prepared and characterized using differential scanning calorimetry and rheological measurements. The glass transition temperature of bitumen increases with an increase of the asphaltene concentration. This correlation can be used to estimate the asphaltene concentration of bitumen samples using DSC measurements. Small-amplitude oscillatory shear data for the bitumen-derived samples were fit by the generalized Maxwell model with good agreement. A constitutive model is proposed, where the zero-shear complex viscosity of the bitumen sample is a strong function of the asphaltene concentration, and it can be used to predict the asphaltene concentration.

Rheological Modeling of Complex Flow Behavior of Bitumen-Solvent Mixtures and Implication for Flow in a Porous Medium

Abstract The viscosity of extra-heavy oils including bitumen can be reduced significantly by adding solvent such as toluene to enhance extraction, production, and transportation. Thus, prediction of viscosity and/or rheology of bitumen-solvent mixtures has become necessary. More so, selecting a suitable rheological model for simulation of flow in porous media has an important role to play in engineering design of production and processing systems. While several mixing rules have been applied to calculate the viscosity of bitumen-solvent mixtures, rheological model to describe the flow characteristics has rarely been published. Thus, in this investigation, rheological behavior of bitumen and bitumen-toluene mixtures (weight fractions of bitumen WB = 0, 0.25, 0.5, 0.6, 0.75, and 1 w/w) have been studied at the flow temperature (75 °C) of the bitumen and in the range of shear rates between 0.001 and 1000 s−1. The data were fitted using different rheological models including the Power law, Cross model, Carreau–Yasuda model, and the newly introduced ones herein named as Cross-Logistic and Logistic models. Then, a computational fluid dynamics (CFD) model was built using a scanning electron microscope (SEM) image of rock sample (representing a realistic porous geometry) to simulate pore scale flow characteristics. The observations revealed that the original bitumen exhibits a Newtonian behavior within the low shear rate region (0.001–10 s−1) and shows a non-Newtonian (pseudoplastic) behavior at the higher shear rate region (100–1000 s−1). Conversely, the bitumen-toluene mixtures show shear thinning (pseudoplastic) behavior at low shear rate region (0.001–0.01), which appears to become less significant within 0.01 to 0.1 s−1, and exhibit shear independent Newtonian behavior within 0.1 and 1000 s−1 shear rates. Moreover, except for the original bitumen, statistical error analysis of prediction ability of the tested rheological models as well as the results from the pore scale flow parameters suggested that the Power law might not be suitable for predicting the flow characteristics of the bitumen–toluene mixtures compared to the other models.

Complex reinforcement potential of inorganic nanoparticles in bitumen

Although the modification of bitumen using nanoparticles has become popular in research studies recently, the degree of modification they provide is still debatable. This paper discusses the effects of three nanoparticles (silicon dioxide, titanium dioxide and calcium carbonate) on the physical properties and rheological behaviour of bitumen. The microstructural properties were evaluated using X-ray diffraction (XRD) and the physical properties were assessed through penetration, softening point and ductility tests. A dynamic shear rheometer was used to investigate the rheological properties of the bitumen, and the results were analysed through the 2S2P1D master curve model and complex reinforcement coefficient RM*. The results of XRD indicated substantial changes in the bitumen structure after adding the nanoparticles. The results showed that the physical properties and rheological behaviour of bitumen were significantly altered by adding the nanosilica to bitumen. However, using the same amount of titanium dioxide and calcium carbonate as additives was less effective than the use of nanosilica. It was also found that the 2S2P1D model and complex reinforcement coefficient RM*were very practical for satisfactory modelling and comparing the rheological properties of nanoparticle-modified binders.

The composition of the material phase responsible for the self-healing of macro-cracks in asphalt mortar beams

ABSTRACT Self-healing of asphalt is assumed to be a flow process where bitumen flows into cracks to close them. Hence, the rheological behaviour of bitumen is one of the main factors affecting self-healing together with damage history, healing duration and pressure (external compressive forces or internal thermal expansion). Bitumen-filler interaction influences the flow and it is hypothesised that the material flowing into cracks during self-healing is a mixture of bitumen, filler and eventually fine aggregates. In the paper, the self-healing ratio was determined by mechanical testing and the self-healing was accelerated by an increase of temperature to 100°C. Material draining from asphalt mortar beams into a horizontal gap, representing a crack, was found to be a mixture of bitumen and aggregates with increasing self-healing observed with increasing bitumen and filler content. For the mortar mixture used in this study, a bitumen content of 5.4 wt% was identified to be the limit for self-healing.

Modified bitumen emulsion by anionic polyurethane dispersion nanocomposites

Different materials and compounds were used for improving mechanical and rheological properties of bitumen. Replacing the traditional bitumen by emulsion bitumen is increasing due to reduced environmental pollution. In recent years, emulsion bitumen modification has been considered to obtain higher efficiency bitumen with water-dispersible polymers. For this purpose, this study intends to investigate the modification of emulsion bitumen using water-dispersible anion polyurethane nanoclay nanocomposite. Since the polymer elasticity property plays an important role in bitumen modification and its properties, anionic polyurethane with different elastic properties was prepared by changing its structure, and its effects on modifying bitumen emulsion were investigated. Preliminary tests of bitumen properties and rheological behaviour analysis were performed on the prepared samples. The results of the tests showed that the penetration-modified bitumen decreased and softening point increased. As the structure of modifier changes, the rheological behaviour of bitumen is improved and changes from viscous to elastic one.

The effect of multiwalled carbon nanotubes on the rheological behaviour of bitumen

An experimental research has been done investigating the effects of the addition of multi-walled Carbon Nanotubes (CNTs) on the rheological behaviour of bitumen and its microstructure. two different types of CNT have been tested, consisted of a product obtained by laboratory synthesis through Catalytic Chemical Vapour Deposition (CCVD) technique and a commercial one, hereinafter are called type 1 and type 2, respectively. Both types of CNTs were completely characterized in terms of morphological, chemical, and structural properties. In addition, the rheological analysis were also conducted on bitumen blends containing CNT providing a complete study understanding the effectiveness of introduced CNT compared to those of commercial ones as for bitumen modification. For this purpose the experimental plan consisted of Trasmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), micro-Raman spectroscopy, and rheological analysis in oscillatory regime.

Laboratory evaluation of the effect of styrene-butadiene-styrene – montmorillonite nanocomposite on rheological behavior of bitumen and performance of stone matrix asphalt mixtures

This study was performed to evaluate moisture susceptibility of different stone matrix asphalt (SMA) mixtures modified with styrene-butadiene-styrene (SBS) and nanoclay. Different samples with vari...

The rheological behavior of bitumen and moisture susceptibility modified with SBS and nanoclay

ABSTRACTThe effect of styrene–butadiene–styrene (SBS) and nanoclay additive on performance of pure bitumen and stone matrix asphalt (SMA) mixture was investigated. Different samples with various percentages of nanoclay (2%, 3%, 4%, and 5%) and SBS (0% and 5%) by weight of bitumen were prepared, and the rheological and chemical behavior of bitumen (rotational viscosity, dynamic shear rheometer, SEM, and FTIR), the indirect tensile strength and moisture susceptibility of different mixtures were evaluated. Based on the results, using nanoclay and SBS polymer can improve the rheological behavior of base binder and the resistance of SMA mixtures against moisture damage.

RHEOLOGICAL PROPERTIES OF STYRENE BUTADIENE RUBBER MODIFIED BITUMEN BINDER

The study investigates the rheological properties of bitumen of 60-70 penetration grade modified with Styrene Butadiene Rubber (SBR). SBR is an elastomer which is an important sort of synthetic rubber. It is a copolymer whose molecular structure primarily consists of organic compound styrene and butadiene chain. Bitumen is visco-elastic in nature. The rate of load application and temperature has a great influence on its performance. Various fundamental properties of bitumen were evaluated, namely complex shear modulus (G*), short-term ageing, long-term ageing, viscosity, penetration and softening point by using Dynamic Shear Rheometer (DSR), Rolling Thin Film Oven Test (RTFOT), Pressure Aging Vessel (PAV), Rotational Viscometer (RV), Penetrometer and Ring and Ball Test, respectively. The binders were mixed with varying percentage of SBR i.e. 0, 1, 2, 3, 4, and 5% by the weight of bitumen binder. The use of SBR has played an active role in improving the viscoelastic properties of bitumen. The use of SBR modifier changes the rheological behavior of bitumen by increasing its complex shear modulus (G*) and the resistance of mixture against permanent deformation (rutting). It was also found that increasing the content of SBR led to the increase in viscosity of modified bitumen, which helps in elevating the mixing and compaction temperature of asphalt mixtures.

EFFICIENT STONE MASTIC ASPHALT WITH USE OF THE COLLOID ADDITIVES

In this article the main operation problems of highways with an asphalt concrete covering in the Republic of Buryatia and transition to pavement from crushed-stone and mastic asphalt concrete in the Republic of Buryatia are considered. Advantage of crushed-stone and mastic asphalt concrete use over the road pavement and its shortcomings is shown; requirements to the road pavement from stone mastic asphalt are revealed; one of its shortcomings elimination options – modification of the bituminous various structure including the colloid additives and properties for increasing straining and strength characteristics of the arranged road pavement is offered; the used additives are described and results of laboratory researches of their application as a part of crushed-stone and mastic asphalt concrete, as well as the analysis of their influence on rheological behavior of bitumen and change of group structure are presented.

Influence of Thermomechanical History on Chemical and Rheological Behavior of Bitumen

It is well-known that asphaltene content plays an important role in determining the high viscosity of bitumen. This paper presents an experimental study of the specific effects of extrusion operating conditions on the physical and chemical properties of bitumen. Five bitumen samples were prepared by twin screw extrusion with different operating conditions (feed rate Q and screw speed N). Physical properties were studied by rheological measurements. Viscosity values were measured by steady state flow tests. Chemical changes in the bitumen structure were followed in the infrared region with attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy by measuring the evolution of the bands areas at 1700 cm–1 (C═O), 1030 cm–1 (S═O), and 1600 cm–1 (aromatic C═C) and the bands between 900 and 730 cm–1 attributed to aromatic C—H. An increase in feed rate Q induces a decrease in the Newtonian viscosity, as a result of a decrease in the asphaltene volume fraction. The characterization by ATR confirms that the decrease in feed rate entails the creation of C═O functional groups and the increase in sulfoxide (S═O) functional groups and C═C bonds, accompanied by a decrease in the C—H aromatic bonds. These results indicate a structure that is more oxidized and more aggregated at low feed rate, certainly as the result of an increase in the residence time into the extruder. The increase in screw speed also induces decreases in the viscosity and the volume fraction of asphaltenes, until a point after which the situation reverses. This change may be explained by the appearance of new peaks between 1200 and 1050 cm–1, attributed to C═S bonds, and between 640 and 540 cm–1, for S—S bonds. A competition between shear rate and residence time takes place. The thermomechanical history has, thus, a great influence on the chemical and rheological behavior of pure bitumen, and the chemical changes observed show that the asphaltene volume fraction is not the unique parameter that explains the variations in viscosity.

Analysis of the effect of wax content on bitumen under performance grade classification

This paper describes an analysis of the effect of wax content on bitumen under performance grade (PG) classification. Wax content affects the performance and rheological behavior of bitumen. Bituminous mixtures with bitumen of high wax content tend to become very soft at high temperatures leading to rutting problem on pavement. Also the rheological behavior of bitumen has a great influence on the behavior of bituminous mixtures. To address the potential adverse effect of wax on bitumen, countries in Europe limit the wax content to 2.2% (BS EN 12606-1). In Mainland China, the standard (JTG F40-2004) classifies bitumen into three grades (Grades A, B and C). Grade A, with wax content below 2.2%, is used for highway pavement construction. Grades B and C, with wax content limits of 3.0% and 4.5% respectively, can only be used on roads with relatively lower traffic. The current binder specifications in Hong Kong Special Administration Region is based on penetration testing, which does not properly account for pavement performance. This paper assesses the effects of wax content and the rheological properties of seven types of bitumens and provides the basis for a performance grading binder standard for Hong Kong.

Rheological Behavior of Concentrated Bitumen in Water Emulsions

The effect of bitumen concentration and mean drop diameter and distribution on the rheological behavior of bitumen in water emulsions was investigated. Results obtained showed that the emulsion viscosity is severely affected by the type of drop size distribution. In fact, emulsions with a bimodal drop diameter distribution exhibit viscosity values which were at least 1 order of magnitude lower than the viscosity of similar emulsions, having the same bitumen concentration and an equivalent mean drop diameter, but with a unimodal distribution. It was also found that concentrated bimodal emulsions behave like Newtonian fluids, while the unimodal counterparts are non-Newtonian and show some pseudoplasticity. Because of their very simple rheological behavior, bitumen in water bimodal emulsions are of great importance in the processes of transporting, handling, and commercializing extremely viscous hydrocarbons.

Bitumen in colloid science: a chemical, structural and rheological approach

The present study gives a new understanding about bitumen's colloidal behavior, related to its chemical composition, microscopic structure and rheological properties. Bitumens possess a strong temperature dependence of rheological properties, governed by the interaction of the individual constituents. Much importance is given to the colloidal index of the bitumen, based on the ratio of the four main chemical components (asphaltenes, resins, aromatics, saturates). Increasing one of these constituents fundamentally changes the structure and the rheological behavior of bitumen. Therefore, a gel bitumen contains high asphaltene/resin concentrations, leading to a network structure with high rigidity and elasticity (high IG∗I, low δ), whereas a sol bitumen possesses a high resin/asphaltene ratio, forming domains of coherent asphaltene micelles which lead to a good time-temperature equivalence in the Black space but also high viscous behavior.

Development of performance-based bitumen specifications for the Gulf countries

The rheological behaviour of bitumen has a great influence on the behaviour of bitumen mixtures. Bitumen plays a significant role in a pavement's ability to withstand thermal and fatigue cracking and contributes to permanent deformation behaviour. The current binder specifications, as applied in the Gulf countries including Saudi Arabia, Kuwait, Bahrain, Qatar, United Arab Emirates and Oman, are based primarily on either penetration or viscosity testing which does not properly account for pavement performance. This research was undertaken to provide a performance-based binder specification for the Gulf countries, based on the findings of the Strategic Highway Research Programme (SHRP) carried out in the United States, considering the prevailing environmental and traffic conditions and type of locally produced bitumen. Results indicated that locally produced 60 70 penetration grade bitumen satisfies the environmental condition of less than 30% of the Gulf countries' area. Air blowing of bitumen is required to satisfy the performance requirement of another 25% of Gulf countries area, while polymer modification is necessary to satisfy the performance requirements for the other parts of the Gulf countries which include eastern parts of Saudi Arabia, Kuwait, Bahrain, Qatar, United Arab Emirates and Oman.