Bitumen Mixtures Research Articles

Comparative Study of Oil-Dilution Capability of Dimethyl Ether and Hexane as Steam Additives for Steam-Assisted Gravity Drainage

Summary Dimethyl ether (DME) was investigated as a potential additive to steam to improve steam-assisted gravity drainage (SAGD) in a previous simulation study. The main objective of this research is to compare DME with n-hexane in terms of the capability of viscosity reduction for Athabasca bitumen. In addition, new experimental data are presented for bubblepoint pressures, densities, and viscosities of Athabasca bitumen and its mixtures with DME and n-hexane. Results show that DME results in slightly higher viscosity than n-hexane when they are mixed with the same Athabasca bitumen at a given pressure, temperature, and molar concentration. For example, the equimolar mixture of DME with Athabasca bitumen is 79 cp, and that of n-hexane with the same bitumen is 49 cp at 328 K and 60 bar. However, the two solvents are equivalent as diluent at temperatures higher than 380 K. For example, the difference is approximately 1 cp at 382 K and 35 bar between the equimolar mixture of Athabasca bitumen with DME and that with n-hexane. The viscosity data measured for bitumen/n-hexane mixtures and bitumen/DME mixtures in this research were correlated with three different viscosity models: a modified Arrhenius model, the power-law model, and the Walther (1931) model. The viscosity data were well-correlated with the modified Arrhenius model, but not with the original Arrhenius (log-linear mixing) rule. The modified Arrhenius model can be used directly with a commercial simulator. Liquid/liquid separation for solvent/bitumen mixtures, which occurred for n-butane/Athabasca bitumen in Gao et al. (2017), was not observed for any of the DME/bitumen and n-hexane/bitumen mixtures in this research. The highest solvent concentration in this study was 80 mol% DME for the DME/bitumen system and 92 mol% n-hexane for the n-hexane/bitumen system.

Preparation and Characterization of Polyester Polyol Modified Bitumen for Pavement Applications

In this study, polymer modified bitumen (PMB) from polyester polyols was prepared by bis(2-hydroxyethyl terephthalate) (BHET) which was obtained by glycolysis of Polyethylene terephthalate (PET) waste. The effect of polyester polyol structure on the rheological properties of PMB was investigated. Polyester polyols obtained by the reaction of various polyols and polycarboxylic acids. POL1, synthesized from BHET and adipic acid (AA), were blended with the bitumen resulting in improved stiffness, rutting resistance and fatigue performance with respect to neat bitumen. Also, the synergistic effects of the polyester polyol addition into styrene-butadiene-styrene modified bitumen (SBS-Bitumen) were investigated where this reference mixture contains SBS loading of 3 % according to the weight of bitumen. Although the addition of POL1(1.3:1) into SBS:Bitumen mixture at 3:3:94 weight ratio didn’t alter the high temperature performance grade of PMB, POL1:SBS:Bitumen exhibited higher softening point, elastic recovery and rutting parameter than reference mixture. The early stage promising results of this study indicated the potential benefits of polyester polyol as bitumen modifier. Also, this study showed that the use of BHET obtained by PET waste as a starting material for polyester polyol synthesis could be an alternative way to utilize plastic waste.

Rheological evaluation of bitumen modified using antistripping additives synthesised from waste polyethylene terephthalate (PET)

ABSTRACT The use of amine-based additives is common practice to improve the stripping resistance and performance properties of bituminous mixtures. This study is concerned with the synthesis of additives derived from waste Polyethylene Terephthalate (PET), and investigation of its effect as an effective modifier for bitumen. Firstly, two amine functionalised additives namely bis(2-hydroxyethyl) terephthalamide (BHETA) and bis(2-aminoethyl) terephthalamide (BAET) were chemically synthesised using an aminolysis process from waste PET. The effects of BAET and BHETA on bitumen and bituminous mixture performance were then identified through conventional binder, Marshall Stability, Hot water stripping, Superpave performance, and Hamburg Wheel Tracking tests. The results indicated that BAET modified bitumen showed a significant improvement in moisture resistance as well as other properties such as enhanced Marshall stability, low and high temperature performance. On the other hand, BHETA modified bitumen did not show similar characteristics and exhibited only a marginal performance improvement as compared to the virgin bitumen. It was inferred from the proposed interaction mechanism that the terminal functional group of the additives has a substantial effect in determining the performance properties of such modified binders. Overall, this study has confirmed the possibility of using waste PET materials as an environmentally friendly modifier for bituminous mixtures.

Effect of additives on liquid–liquid equilibrium properties of butane/bitumen systems with applications to solvent aided bitumen recovery processes

Solvent-aided bitumen recovery processes are relatively new approaches to reduce the negative environmental impacts and production costs of steam assisted gravity drainage (SAGD). Thermo-physical properties of these systems such as density, viscosity, phase partitioning and saturation pressure are of great importance in design of solvent-aided processes. Butane is a promising solvent for solvent-aided bitumen recovery processes. Addition of light or heavier solvents to butane can provide an engineering solution to improve the efficiency of solvent-aided processes. In this study, equilibrium measurements of butane and bitumen mixture were conducted at temperatures of 40 and 60°C and pressures well above vapour pressure of the solvent. Then, the effect of introducing a second solvent as an additive to the butane–bitumen mixture was investigated. Propane, toluene and dimethyl ether were added to the original mixtures of butane and bitumen in separate sets of experiments and changes in thermo-physical properties were determined. It was determined that adding butane can lower the viscosity of the bitumen by several orders of magnitude. It was also concluded that although propane can significantly increase the saturation pressure of the mixture, it results in higher amount of asphaltene precipitation. The effect of dimethyl ether however is favourable because not only increases the vapour pressure but also reduces the asphaltene precipitation similar to toluene.

Effects of different bitumen modifiers on the rutting and cracking resistance of hot mix asphalts

ABSTRACTIn this study, four different additives (Styrene–butadiene–styrene (SBS), Trinidad Lake Asphalt (TLA), Iranian Gilsonite (IG) and American Gilsonite (AG)) were used in bitumen modification. The rheological properties of bitumen were improved with the additive usage, and the desired performance grade (PG 70-34) was achieved by using additives in pure bitumen (PG 58-34) at the indicated ratios. Wheel tracking tests and semi-circular bending tests were applied for hot mix asphalt (HMA) samples. The main results showed that all the additives increased resistance to permanent deformation of HMAs, and that TLA was the most effective additive. In addition, it was found from the semi-circular bending tests that deformation values of mixtures prepared with modified bitumens and subjected to long-term ageing decreased. As a result, long-term aged and modified bitumen mixtures exhibited more brittle behaviour. The increase in maximum load values led to an increase in the area under the load-strain curves. Thus, crack propagation resistance of mixtures prepared with modified binders was increased.

The effect of freeze-thaw cycles on durability properties of SBS-modified bitumen

To study the high-temperature characteristics of bitumen under the influence of freeze-thaw cycles, the results of DSR tests of bitumen and SBS-modified bitumen after 0, 3, 6, 9, 12, 15, and 18 freeze-thaw cycles were investigated. First, based on the simplified model for the DSR tests, the relation between the rheological parameters of the bitumen was analyzed. Then, in combination with the MSCR tests of the SBS-modified bitumen after freeze-thaw cycles, the relation between %R and Jnr was discussed. Finally, FTIR was used to analyze the changes in the chemical composition of the bitumen under freeze-thaw cycles. The results showed that the incorporation of SBS modifiers can increase the elasticity of the bitumen significantly and slow the tendency of the bitumen’s complex shear modulus to increase with the freeze-thaw cycles to a certain extent. The SBS modifiers also can reduce the bitumen’s temperature sensitivity and improve its rutting resistance. After the freeze-thaw cycles, G∗/sinδ decreased as temperature increased, and G∗sinδ showed an exponential decay with increasing temperature. With an increase in the number of freeze-thaw cycles, G∗sinδ of the bitumen and SBS-modified bitumen increased gradually, which indicated that the bitumen’s fatigue resistance weakens gradually after freeze-thaw cycles. The %R0.1 and %R3.2 of SBS-modified bitumen showed a decreasing trend under different stress levels, and the %R3.2-%R0.1 increased, which indicates that bitumen’s high temperature characteristics and temperature fatigue performance show an attenuating trend. The difference between the FTIR spectra of the SBS-modified bitumen fingerprint area after a freeze-thaw cycle was reflected largely in the significant increase in the 1700 cm−1 carbonyl group and 1031 cm−1 sulfoxide group peaks, while the two peaks at 967 cm−1 and 700 cm−1 were relatively stable. These results provide a theoretical basis and technical support for the design, material selection, popularization, and application of an SBS-modified bitumen mixture in roads in regions with seasonal freezing.

Investigation of road performances of reaction-rejuvenated SBS modified bitumen mixture

As time goes on, more and more waste SBS modified bitumen mixture (SMBM) located at the top-layer of high-grade roadway requires to be recycled for repaving with high-quality performance. To solve the problem, the reactive rejuvenating systems (BUDGEs and BUDGE-MDIs) containing 1,4-butanediol diglycidyl ether (BUDGE) and/or diphenyl methane diisocyanate (MDI) and fluid catalytic cracking slurry (FCC slurry) are applied to the rejuvenation of aged SMBM. In this paper, the effects of BUDGEs and BUDGE-MDIs on the moisture damage, rutting performance, low-temperature flexural characteritics and the macroscopic fracture morphology of aged SMBM are systematically investigated. The results of the moisture damage suggest that the reactive rejuvenating systems, particularly BUDGE-MDIs, can obviously contribute for improving the water stability approaching to the level of the fresh SMBM and effectively retain the higher water resistance after secondary immersion. The results of the rutting performance demonstrate that BUDGE-MDIs can inhibit the significant reduction of the elastic components of the aged binder and preferably remains the dynamical stability at high temperature when compared with BUDGEs. The low-temperature performance indicates that BUDGE-MDIs has remaining positive effects on the low-temperature crack behavior depression of aged SMBM in comparison with BUDGEs, and the anti-crack ability somewhat deteriorates after long-term loads, while from the fracture morphology, it finds the reactive rejuvenating systems can recover the combining force of aged binder to some extent for the marked reduction in the brittle fracture of aged SMBM at low temperature.

The effect of IPC formulation on bitumen properties – An experimental study

Use of chemicals as an additive during steam-based bitumen recovery processes has been an active topic for research and development in the last four decades. In this study, thermo-physical properties of mixtures of bitumen with a newly developed chemical are reported. This new chemical technology (i.e. IPC as referred in this paper) is a proprietary mixture of surfactants that has been used in several techniques associated with surface extraction as well as in-situ recovery of heavy oil and bitumen. This formulation of solvents and surfactants is reusable, low foaming, non-flammable, not acutely toxic and non-carcinogenic. A series of tests were conducted to measure density and viscosity of a bitumen, IPC, and different mixtures of bitumen-IPC at several pressure, temperature and chemical composition conditions. It was observed that solubility of IPC in bitumen was small, and its effects on the oil phase viscosity and density could not be separated from its effects on bulk properties caused by dispersed emulsified droplets of IPC. The impact of IPC on viscosity of mixture was more pronounced than its effect on mixture density. A very complex emulsion was formed upon contact of IPC with bitumen. The results of these tests will be useful in designing a steam-based bitumen recovery process with IPC as the chemical additive. Details of thermal stability analysis of IPC are also presented.

Impact of low viscosity grade bitumen on foaming characteristics

The construction of highway infrastructure requires large quantities of construction materials and is an energy-intensive activity. Issues like scarcity of construction materials, increasing cost of materials, increasing cost of construction processes, and the emphasis on less polluting construction procedures have led to advancements in pavement construction practices. One such example is foamed bitumen technology. In this process, cold water is injected into a hot bitumen medium, which leads to drastic expansion of bitumen, forming a fine mist or foam. The performance of foam bitumen mixtures is influenced by the bitumen properties, as well as by the foaming process. This paper deals with research on the rheology of three different types of binders having low viscosity (in the range of 500 to 3 000 Poise at 60°C) on foaming characteristics. The water content and temperature also have significant effects on foam decay and the expansion ratio of foam. Results show that a low viscosity bitumen consumes less energy during the foam process compared to high viscosity bitumen. The conclusion drawn from this study is that the expansion ratio and half-life of foam bitumen depend on the rheology of the bitumen, as well as on the chemical composition of the bitumen. It was concluded that, with an increase in carbonyl and sulphoxide compound, the expansion ratio decreases and the half-life increases.

Application of LSSVM algorithm as a novel tool for prediction of density of bitumen and heavy n-alkane mixture

ABSTRACTThe most of oil reservoirs in the world are heavy oil and bitumen reservoirs. Due to high viscosity and density of these types of reservoirs the production has problems so importance of enhanced oil recovery (EOR) processes for them is clear. The injection of solvents such as tetradecane is known as one of methods which improve oil recovery from bitumen reservoirs. In the present investigation, the Least squares support vector machine (LSSVM) algorithm was used to estimate density of Athabasca bitumen and heavy n-alkane mixture in term of temperature, pressure and weight percent of the solvent. The Root mean square error (RMSE), average absolute relative deviation (AARD) and the coefficient of determination (R2) for total dataset are determined 0.033466, 0.0025686 and 1 respectively. The predicted results indicate that the LSSVM algorithm has potential to be a predicting machine for the bitumen-heavy alkane mixture density prediction.

Emulsification of Athabasca bitumen by organic alkali: Emulsion phase behavior and viscosity for bitumen/brine/triethylenetetramine

Recovery of bitumen commonly uses steam assisted-gravity drainage, in which water throughput is intrinsically high. A large amount of condensed water near thermal fronts tends to substantially decrease the effective permeability to bitumen in the conventional gravity drainage process. This research investigates a potential way to use the condensed-water phase as an effective carrier for bitumen by making oil-in-water (o/w) emulsion. The expected mechanism depends on emulsification of bitumen into the water phase by natural surfactants that are generated through reactions of acidic oil components with organic alkali.The main objective of this paper is to study the ability of an organic alkali to create o/w emulsions that are much more mobile than the original bitumen. Triethylenetetramine (TETA) was selected as organic alkali for this paper with no other additives. The main contribution of this paper is a new set of experimental data (phase behavior and viscosities) for emulsions for mixtures of Athabasca bitumen, TETA, and NaCl brine at a wide range of alkali concentrations, salinities, and water-to-oil ratios (WORs) at temperatures up to 373 K.Results show that the o/w emulsions created by TETA can be an effective bitumen carrier with a low viscosity and high bitumen content in the emulsion. It is possible to create o/w emulsions by adding a small amount of TETA to Athabasca bitumen and NaCl brine. Single-phase o/w emulsions, which are desirable as a bitumen carrier, were observed for TETA concentrations below 5.0 wt% at salinities 0 ppm and 1000 ppm at 373 K. The bitumen content in o/w emulsion was the highest for 2.0 wt% TETA samples, and it increased with increasing temperature. In comparison to the original bitumen, o/w emulsions were 4–5 orders of magnitude less viscous at 298 K, 2 to 3 orders of magnitude less viscous at 323 K, and 1 to 2 orders of magnitude less viscous at 353 K.

Nonlinearity of bituminous materials for small amplitude cyclic loadings

This paper focuses on the influence of the cyclic loading amplitudes on the behaviour of bitumen and bituminous mixtures. The present work considers only rather small strain amplitude (lower than 100 µm/m for mixtures and 10% for bitumen). Complex modulus tests on mixtures were conducted at four levels of strain amplitude for a large range of temperatures and frequencies. Tension–compression tests at the temperatures lower than 20°C and shear tests at temperatures higher than 20°C were performed to measure the complex modulus of bitumen which is used to produce the mixtures. Moreover, individual strain tests, strain sweep tests and fatigue tests at 10, 30 and 50°C were carried out to study the influence of the strain amplitude and cyclic effects on the complex modulus of bitumen. The obtained results indicated that the nonlinearity (effect of strain amplitude) on both bitumen and bituminous mixtures respects the Time Temperature Superposition Principle (TTSP). However, the temperature–frequency has inverse effects on the nonlinear behaviour of bitumen and bituminous mixtures. The cyclic effect was shown to be not negligible when analysing the nonlinearity phenomenon.

Effect of fast pyrolysis bio-oil from palm oil empty fruit bunch on bitumen properties

Bitumen shortage has triggered the exploration of another alternative waste material that can be blended with conventional bitumen. This study presents the performance of pyrolysis bio-oil from palm oil empty fruit bunch (EFB) as an alternative binder in modified bitumen mixtures. The palm oil EFB was first pyrolyzed using auger pyrolyzer to extract the bio-oil. Conventional bitumen 80/100 penetration grade was used as a control sample and compared with samples that were modified with different percentages, i.e., 5% and 10%, of pyrolysis EFB bio-oil. The physical and rheological properties of the control and modified bitumen samples were investigated using penetration, softening point, viscosity and dynamic shear rheometer (DSR) tests. Results showed that the addition of EFB bio-oil softened the bitumen with high penetration and a reduction in softening point, penetration index, and viscosity. However, the DSR results showed a comparable rutting resistance between the bitumen samples containing EFB bio-oil and virgin bitumen with a failure temperature achieved greater than 64°C.

IMPACT OF RECYCLED ASPHALT PAVEMENT ON PROPERTIES OF FOAMED BITUMINOUS MIXTURES

In recent years, the use of foamed bitumen technology along with Reclaimed Asphalt Pavement is gaining popularity across the world. The mechanical response of foamed bitumen mixtures containing reclaimed asphalt pavement is significantly influenced by constituent material properties and aggregate gradation. This article presents results from a study where foamed bitumen mixtures conforming to Indian specifications were evaluated. For this purpose, foamed bitumen mixtures using a different percentage of reclaimed asphalt pavement and bitumens were prepared. Initially, the foaming characteristics of virgin bitumens were evaluated to optimize for optimum water content and foaming temperature. In the second stage, mixture design was conducted to optimize for foamed bitumen content in foamed bitumen mixtures containing a different percentage of reclaimed asphalt pavement. Finally, these foamed bitumen mixtures were evaluated for their mechanical properties. The results from this laboratory study indicated properties of foamed bitumen and foamed mixtures are significantly influenced by properties of bitumen, the quantity of bitumen, and reclaimed asphalt pavement. Among the different mixtures, a mixture containing 50% reclaimed asphalt pavement exhibited best results in resilient modulus and resistance to moisture damage tests. A mixture containing 80% reclaimed asphalt pavement also shows acceptable strength and resistance to water susceptibility. Thus, it is possible to design high-quality bituminous mixes using higher reclaimed asphalt pavement percentages, which meet the required volumetric and desired performance criteria.

Investigation of the effect of nano-silica on thermal sensitivity of HMA using artificial neural network

Due to changes in weather conditions, engineers try to improve performance characteristics and properties of asphalt mixtures using additives. In this regard, modifiers are used because bitumen cannot have a good performance in all environmental and loading conditions. This paper examined the impact of one of the most efficient and widely used nanomaterials in various industries called nano-silica (Nano SiO2) on the thermal properties of bitumen and asphalt mixture. Using a solution that can reduce the cost and time of assessment is very important. Using artificial neural networks in many cases facilitates operations on data engineering sciences. It is necessary to ensure that a comprehensive study is performed through considering all or most of the parameters affecting the behavior. The aim of this study was to evaluate temperature sensitivity of asphalt mixture modified with nano-silica. To achieve this goal, 5 types of mixtures with different percentage of nano-silica (0, 0.2, 0.4, 0.7 & 0.9%) were prepared and the temperature sensitivity of modified mixtures was evaluated. Results showed that nano-silica can improve the temperature sensitivity of asphalt mixtures. Moreover, the thermal sensitivity of asphalt mixtures modified with nano-silica using artificial neural network and methods of multilayer perceptron (MLP) and radial basis function (RBF) was simulated and analyzed.

Applying FCM-ANFIS algorithm as a novel computational method for prediction of viscosity of bitumen and heavy alkane mixture

ABSTRACTRecently the studies expressed that the noticeable number of oil reservoirs in all over the world are heavy oil and bitumen reservoirs. So the importance of enhancement of oil recovery (EOR) processes for heavy oil and bitumen reservoirs is highlighted. The Dilution of the reservoir fluid by solvents such as tetradecane is one of well-known methods for these types of reservoirs which effects oil recovery by decreasing viscosity. In the present study, Fuzzy c-means (FCM) algorithm was coupled with Adaptive neuro-fuzzy inference system (ANFIS) to predict viscosity of bitumen and tetradecane in terms of temperature, pressure and weight percent of tetradecane. The coefficients of determination for training and testing steps were calculated such as 0.9914 and 0.9613. The comparison of results and experimental data expressed that FCM-ANFIS algorithm has great potential for estimation of viscosity of bitumen and tetradecane.

Rapid Determination of Bitumen Content in Athabasca Oil Sands by Laser-Induced Breakdown Spectroscopy

Evaluation of bitumen content in oil sands feedstock is important to control the extraction process and improve the recovery efficiency. Current standard techniques for bitumen determination in oil sands ore suffer whether from their time-consuming labor intensive method of sample preparations or from requiring a high number of samples for calibration purposes. The analysis of bitumen ore samples is very challenging for the analytical chemist due to its nature of several phases of wet and dry particles and heterogeneous mixture of clay, bitumen, water, and solid contents. In this paper, we present a new enabling method using LIBS to determine rapidly and without sample preparation the bitumen content in oil sands ores. A qualitative study by principal component analysis was first done, and then a partial least-squares method was performed to assess the feasibility of determining bitumen by LIBS. The results show a good correlation between LIBS spectra and bitumen content and a prediction averaged absolute...

Application of fuzzy c-means algorithm as a novel method to predict density of mixtures of Athabasca bitumen and heavy n-alkane

The significant number of oil reservoir are bitumen and heavy oil. One of the approaches to enhance oil recovery of these types of reservoir is dilution of reservoir oil by injection of a solvent such as tetradecane into the reservoirs to modify viscosity and density of reservoir fluids. In this investigation, an effective and robust estimating algorithm based on fuzzy c-means (FCM) algorithm was developed to predict density of mixtures of Athabasca bitumen and heavy n-alkane as function of temperature, pressure and weight percent of the solvent. The model outputs were compared to experimental data from literature in different conditions. The coefficients of determination for training and testing datasets are 0.9989 and 0.9988. The comparisons showed that the proposed model can be an applicable tool for predicting density of mixtures of bitumen and heavy n-alkane.

Influence of fibres on rheological properties and toughness of bituminous binder

Many studies have been made to examine different ways to modify bitumen and asphalt mixtures in response to increasing performance requirements. One of these is the use of additive materials and in this study, the potential of cellulose and glass fibres to modify the rheological properties of bitumen has been investigated. To achieve this, mixtures of bitumen with different contents of fibre were prepared and the properties of the bitumen and resulting modified binders were tested (penetration, softening point, viscosity and double edge notch tension test along with rheological testing in the dynamic shear rheometer). The experimental results demonstrated that adding fibres improves the rheological properties of bitumen across a range of loading frequencies and temperatures. Adding fibre reduced the penetration and increased the softening point and viscosity of bitumen implying improved rutting resistance of asphalt mixtures using these mastics. Finally this investigation established that adding fibre to bitumen improved its toughness, which could lead to improvement in asphalt fatigue performance. However, there are some limitations that are also discussed.

The influence of vehicle speed changes at mechanistic performance of asphalt mixture

Asphalt mixture is a viscoelastic material. Several factors affect the behavior of a viscoelastic material. Temperature and loading time are the most critical of these parameters. Vehicle speed affects time loading, therefore it’s very important to know the influence of vehicle speed changes in mechanistic performance of bitumen and asphalt mixture with different aggregate gradation types, namely dense graded and gap graded. Based on data of bitumen penetration, bitumen softening point, volume of bitumen, volume of aggregate and volume of voids, mechanistic performance of bitumen and asphalt mixture influenced by vehicle speed changes can be predicted using the software BANDS 2.0. The variation of vehicle speed will be carried out to see its significance. The results of the BANDS 2.0 simulation show that vehicle speed changes influence bitumen stiffness, asphalt mix stiffness and fatigue life asphalt mix. The higher the vehicle speed is, the higher bitumen stiffness and asphalt mix stiffness will be, but fatigue life asphalt mix will be lower. At the same vehicle speed, asphalt mix stiffness of dense graded mixture will be higher than gap graded mixture. The other way for fatigue life asphalt mix.