Showing papers on "Asphalt published in 2010"
TL;DR: In this paper, the effect of different fibers, mixing procedures and executive problems on asphalt concrete is inspected, where the authors focus on the first side of the coin and investigate FRAC materials modified by random fiber inclusion.
347 citations
TL;DR: A general overview of microwave applications in bitumen extraction, upgrading heavy oils, removing heteroatoms, and underground heating of oil sands to reduce bitumen viscosity and allow it to be pumped to the surface is provided in this article.
241 citations
TL;DR: In this article, the authors investigated the use of recycled concrete aggregates (RCA) as sustainable aggregates in Hot Mix Asphalt (HMA) for low-volume roads.
215 citations
TL;DR: In this paper, high-precision gas chromatography measurements of 76 speciated C2-C10 VOCs (alkanes, alkenes, alkynes, cycloalkane, aromatics, monoterpenes, oxygenated hydrocarbons, halocarbons, and sulphur compounds) were performed using the NASA DC-8 airborne laboratory as a research platform.
Abstract: . Oil sands comprise 30% of the world's oil reserves and the crude oil reserves in Canada's oil sands deposits are second only to Saudi Arabia. The extraction and processing of oil sands is much more challenging than for light sweet crude oils because of the high viscosity of the bitumen contained within the oil sands and because the bitumen is mixed with sand and contains chemical impurities such as sulphur. Despite these challenges, the importance of oil sands is increasing in the energy market. To our best knowledge this is the first peer-reviewed study to characterize volatile organic compounds (VOCs) emitted from Alberta's oil sands mining sites. We present high-precision gas chromatography measurements of 76 speciated C2–C10 VOCs (alkanes, alkenes, alkynes, cycloalkanes, aromatics, monoterpenes, oxygenated hydrocarbons, halocarbons and sulphur compounds) in 17 boundary layer air samples collected over surface mining operations in northeast Alberta on 10 July 2008, using the NASA DC-8 airborne laboratory as a research platform. In addition to the VOCs, we present simultaneous measurements of CO2, CH4, CO, NO, NO2, NOy, O3 and SO2, which were measured in situ aboard the DC-8. Carbon dioxide, CH4, CO, NO, NO2, NOy, SO2 and 53 VOCs (e.g., non-methane hydrocarbons, halocarbons, sulphur species) showed clear statistical enhancements (1.1–397×) over the oil sands compared to local background values and, with the exception of CO, were greater over the oil sands than at any other time during the flight. Twenty halocarbons (e.g., CFCs, HFCs, halons, brominated species) either were not enhanced or were minimally enhanced ( In addition to the emission of many trace gases, the natural drawdown of OCS by vegetation was absent above the surface mining operations, presumably because of the widespread land disturbance. Unexpectedly, the mixing ratios of α-pinene and β-pinene were much greater over the oil sands (up to 217 pptv and 610 pptv, respectively) than over vegetation in the background boundary layer (20±7 pptv and 84±24 pptv, respectively), and the pinenes correlated well with several industrial tracers that were elevated in the oil sands plumes. Because so few independent measurements from the oil sands mining industry exist, this study provides an important initial characterization of trace gas emissions from oil sands surface mining operations.
208 citations
TL;DR: In this paper, it is demonstrated that a previously developed method employing ionic liquids (ILs) together with a nonpolar solvent such as toluene can effect a separation at ambient temperatures (∼25 °C), although with greater difficulty than Canadian oil sands.
Abstract: Hot or warm water processes are used to extract bitumen from Canadian oil or tar sands. The application of these methods to the processing of tar sand deposits found in the Western United States, notably Utah, has not been commercially successful, however, because of the consolidated nature of the deposits and the high viscosity of the bitumen. It is demonstrated here that a previously developed method employing ionic liquids (ILs) together with a nonpolar solvent such as toluene can effect a separation at ambient temperatures (∼25 °C), although with greater difficulty than Canadian oil sands. Essentially, a multiphase system consisting of a sand and clay slurry, an ionic liquid layer, and an organic layer containing the bitumen can be formed by simply mixing the components. More than 90% of the bitumen is released from the sand, but only in successive extractions. Water is not used in this stage of the separation, but relatively small amounts are used to separate entrained IL from the sand and clays.
159 citations
TL;DR: In this article, the authors compared the performance of asphalt rubber mixtures (with dense and gap-graded aggregate gradation) with the conventional dense graded mixture most used in Brazil, and found that the use of the asphalt rubber binder improves significantly the resistance to rutting.
154 citations
TL;DR: In this article, the authors examined fibers' physical properties, reinforcing effects and mechanisms for stabilizing and reinforcing asphalt binder, and found that fiber reinforced asphalt matrix through its functions of spatial networking, adhesion and stabilization.
153 citations
TL;DR: In this paper, the stability and viscosity of W/O emulsions and their application for heavy oil pipeline transportation were investigated using two Iranian crude oil samples using Triton X-100 surfactant.
150 citations
TL;DR: In this paper, a methodology of quantifying healing using the dissipated energy approach and the dynamic shear rheometer test with a specifically designed intermittent loading sequence is introduced, which has been successfully applied to study hot mix asphalt (HMA) mixture healing.
Abstract: Asphalt mixtures have two healing mechanisms: adhesive healing at the asphalt-aggregate interface and cohesive healing within asphalt binders. This study investigates the effects of cohesive healing exclusively, without considering the interaction of aggregates. This study also introduces a methodology of quantifying healing using the dissipated energy approach and the dynamic shear rheometer test with a specifically designed intermittent loading sequence. The ratio of dissipated energy change approach, which is based on the fundamental concept of dissipated energy and has been successfully applied to study hot mix asphalt (HMA) mixture healing, is applied to the binder. By doing so, a healing rate, defined as the rate of dissipated energy recovery per unit of rest time, is used to quantify the healing potential of asphalt binders. The results indicate that binder type, strain level, and temperatures have important impact on healing. It is recommended that the research methods introduced in this study be further applied to asphalt mastics and sand asphalt mixes to study adhesive and cohesive healing in HMA mixtures and provide fatigue-healing information for pavement design.
141 citations
Dissertation•
01 Jan 2010
140 citations
TL;DR: The impact of salt on asphalt binders was first studied through basal experiments of binders in this paper, and the complex influence of freeze-thaw cycles and salt on strength, volume and weight of three types of asphalt mixtures was then investigated through freeze -thaw tests.
TL;DR: In this article, the effect of water immersion on adhesive and cohesive properties of asphalt-aggregate systems was investigated using a modified version of the PATTI test, which is able to evaluate with good precision the pull-off strength and its repeatability depends on the failure type (adhesive or cohesive).
Abstract: The bond strength between asphalt and aggregate plays a fundamental role in evaluating the moisture sensitivity of HMA Mixtures In this study the effect of water on adhesive and cohesive properties of asphalt-aggregate systems was investigated using a modified version of the PATTI The device was used to measure the pull-off strength on different asphalt-aggregate combinations and to evaluate the influence of water immersion at two different temperatures In particular, six asphalt binders were employed in combination with two aggregate types, having different asphalt affinity The effect of the aggregate surface temperature during specimen preparation was also tested In the first phase of the study the within-laboratory repeatability of the test procedure was investigated The results showed the PATTI test is able to evaluate with good precision the pull-off strength and that its repeatability depends on the failure type (adhesive or cohesive) In the second phase of the study a full factorial
TL;DR: In this article, indirect tensile tests were carried out on hot mix asphalt HMA and stone matrix asphalt SMA mixtures comprising different nominal maximum aggregate sizes NMAS in three temperatures of 5, 25 and 40°C Stiffness modulus, fatigue lives and fatigue prediction equation of the mixtures were developed and characterized in terms of aggregate gradation type, coarseness and fineness of gradation, temperature and asphalt content
TL;DR: Bentonite clay and organically modified bentonite (OBT) were used to reinforce and modify a bituminous paving asphalt binder as mentioned in this paper, and the modified asphalt binders were produced by melt processing under sonication and shearing stresses.
TL;DR: In this article, heavy oil (Canada oil sand bitumen) upgrading in high density water (100 and 200 kg/m 3 ) at 723 K was performed by a batch reactor.
Abstract: Heavy oil (Canada oil sand bitumen) upgrading in high density water (100 and 200 kg/m 3 ) at 723 K was performed by a batch reactor. Yields of asphaltene, maltene, and coke were evaluated. With increasing water density, the rate of coke formation was promoted. To get some hints of coke formation mechanism, the formed coke was observed by scanning electron microscope (SEM). The most part of the coke formed st neat pyrolysis (pyrolysis in the absence of high density water) was coalescent structure of some small coke particles, while that at pyrolysis in the presence of water (200 kg/m 3 of water density) was porous structure that indicated occurrence of phase inversion of coke precursors. Based on the results, the reaction mechanism of the heavy oil upgrading was considered: lighter oil was extracted in high density water and the concentration of light hydrocarbon decreased in a heavier oil phase, while the concentration of heavier oil in the oil phase increased. Thus, the lighter oil decomposed further in high density water phase and the heavier oil in the oil phase combined together to form coke due to its higher concentration.
TL;DR: In this paper, the effect of the addition of two different organoclays as a third component in polymer-modified asphalts has been investigated and it was shown that the clay had a compatibilizing effect on asphalt and polymer and that a high compatibility between clay and polymer led to a better dispersion of the polymer in the asphalt.
TL;DR: In this article, the discovery of waste engine oil residues in pavements across Ontario, Canada has been investigated using X-ray fluorescence (XRF) analysis, which suggests that typical modification levels are in the 5-20% range.
Abstract: This paper documents the discovery of waste engine oil residues in pavements across Ontario, Canada. We have found that recovered asphalts from a large majority of poorly performing contracts test positive for zinc through X-ray fluorescence (XRF) analysis. In contrast, neither the aggregates nor any of the well-performing asphalts showed any signs of the metal. Since zinc dialkyldithiophosphates are universal additives in engine oils, we inferred that the use of waste oil residues in asphalt must be widespread. Further analysis of 2008 quality assurance samples taken for the Ontario Ministry of Transportation substantiated this, with most samples testing positive for zinc. XRF analysis of straight waste oil residues suggests that typical modification levels are in the 5–20% range. The damaging effect of this additive through increased physical and chemical hardening is briefly discussed with reference to previous studies on unexplained, premature and excessive thermal cracking.
TL;DR: In this paper, the authors evaluated the effects of different quantities of a WMA additive known as Sasobit ® on the required heat energy and the amount of CO 2 produced to increase the temperature of two aggregates from three sources and one binder from 25°C to the point of mixing.
TL;DR: In this article, the authors performed complex viscosity and phase-angle measurements for Athabasca bitumen and Maya crude oil with a rotational rheometer using parallel plates and a double gap cylinder in the oscillatory mode over the temperature range of (200 to 410) K.
Abstract: Complex viscosity and phase-angle measurements for Athabasca bitumen and Maya crude oil were performed with a rotational rheometer using parallel plates and a double gap cylinder in the oscillatory mode over the temperature range of (200 to 410) K. A large range of shearing conditions were applied (frequency of oscillations, shear strain, or stress), and up to three orders of magnitude of variations in measured viscosity values for individual samples at a fixed temperature were obtained. Athabasca bitumen and Maya crude oil were found to be solid-like materials up to (260 to 280) K and (230 to 240) K, respectively. Athabasca bitumen is a non-Newtonian shear-thinning fluid up to (310 to 315) K, whereas Maya crude is a shear-thinning fluid up to (280 to 285) K. Both are Newtonian at higher temperatures. Maya crude oil was also found to possess thixotropic behavior. Athabasca bitumen reveals the thermal irreversibility of complex viscosity, if it is heated above 360 K. These rheological behaviors are attribu...
TL;DR: In this article, a specific laboratory study aiming at perfectioning recycled asphalt with high mechanical performance, for surface and structural layers of flexible pavements, was conducted, where the aim was to combine in the same material the maximum possible quantity of recycled asphalt (RA), coming from degraded asphalt layers, together with high structural performance of the recycled mixtures obtained (mainly stability, load spreading properties, rutting and fatigue resistance) that should not be lower, or possibly better than those offered by traditional asphalt mixture, made with virgin binder and aggregate.
Abstract: The paper deals with a specific laboratory study aiming at perfectioning recycled asphalt with high mechanical performance, for surface and structural layers of flexible pavements. The aim of the research was to combine in the same material the maximum possible quantity of recycled asphalt (RA), coming from degraded asphalt layers, together with high structural performance of the recycled mixtures obtained (mainly stability, load spreading properties, rutting and fatigue resistance) that should not be lower, or possibly better than those offered by traditional asphalt mixture, made with virgin binder and aggregate. For this purpose, innovative recycled mixtures, close-graded and with high mechanical performance, characterized by high content of recycled asphalt (up to 50%) and designed for surface, binder and base layers were investigated in a laboratory study. The results of physical and mechanical characterization tests show that, by controlling the homogeneity of recycled material and by using new bitumen with adequate rheological properties, it is possible to obtain paving mixtures with high content of recycled materials that, in relation to their intended use (surface, binder or base layer), can be considered as “high-performance mixtures”.
TL;DR: In this paper, micromechanical properties such as hardness and Young's modulus of asphalt binders and asphalt concrete are determined by nano-indentation experiments, which has been used to measure nanomechanical properties of surface layers of bulk materials and of thin films.
Abstract: Nanoindentation is a relatively new technique which has been used to measure nanomechanical properties of surface layers of bulk materials and of thin films. In this study, micromechanical properties such as hardness and Young’s modulus of asphalt binders and asphalt concrete are determined by nanoindentation experiments. Indentation tests are conducted on a base binder and two polymer-modified performance grade (PG) binders such as PG-70-22 and PG76-28. In addition, two Superpave asphalt mixes such as SP-B and SP-III are designed using these PG binders, and the corresponding mixes are compacted to prepare asphalt concrete. Aggregate, matrix (Materials Passing No. 4 sieve) and mastic (Materials Passing No. 200 sieve) phases of each asphalt concrete sample are indented using both Berkovich and Spherical indenters. In nanoindentation, an indenter penetrates into asphalt material and the load (milli-Newton) and the depth (nanometers) of indentation are recorded continuously. Indentation load versus displacem...
TL;DR: In this article, the authors evaluated the workability and compactability of different warm-mix additives preblended in a polymer-modified asphalt binder at varying percentages and compared different test procedures.
Abstract: One of the main benefits advertised about the use of warm-mix asphalt is the increased workability at conventional and lower compaction temperatures. From a field perspective, "workability" is commonly defined as the asphalt mixture property that describes the ease with which the asphalt mixture can be placed, worked by hand, and compacted to the desired mat density. Unfortunately, a laboratory property and test condition have yet to be developed to quantify these field characteristics. A research effort to evaluate the workability and compactability of different warm-mix additives preblended in a polymer-modified asphalt binder at varying percentages is summarized. Different test procedures, both asphalt binder related and asphalt mixture related, were evaluated and compared. Test results indicated that conventional mixing and compaction temperature asphalt binder tests were insensitive to the different warm-mix additives and dosage rates. Compaction data obtained with the gyratory compactor also indicat...
TL;DR: In this paper, improved test methods for determining laboratory mixing and compaction temperatures of modified and unmodified asphalt binders were identified, which will be of immediate interest to materials engineers in state highway agencies and the hot-mix asphalt industry.
Abstract: This report identifies improved test methods for determining laboratory mixing and compaction temperatures of modified and unmodified asphalt binders. The report will be of immediate interest to materials engineers in state highway agencies and the hot-mix asphalt (HMA) construction industry.
TL;DR: In this article, the authors proposed a model that allows estimation of stiffening effects based on primary binder and filler properties, based on a conceptual model provided in an earlier publication for understanding the mechanism by which the filler stiffens the asphalt mastic.
Abstract: Many studies have focused on modelling the stiffening effect of mineral filler on asphalt binder. However, the interaction between both constituents was always a challenge to address. Current European as well as North American specifications includes limits on stiffening effects of fillers that are mostly empirically driven and hard to include in a mixture design process. This study offers a model that allows estimation of stiffening effects based on primary binder and filler properties. This study builds on a conceptual model provided in an earlier publication for understanding the mechanism by which the filler stiffens the asphalt mastic. The model hypothesizes that change of mastic complex modulus with filler content follows two phases; a diluted phase and a concentrated phase. In the diluted phase, the stiffening effect of the filler on the binder follows a linear filling trend where interaction between filler and binder is minimal. On the other hand the effect of the filler departs from the ...
TL;DR: The use of tire cord mesh in reinforcing asphalt pavement has been introduced and accurately observed in this paper, and the results show that the tire cord meshes reinforcement significantly increases the asphalt pavement resistance against cracking and increases its service life while decreasing maintenance and rehabilitation costs.
01 Jan 2010
TL;DR: In this article, the authors investigated the mechanics of additional viscosity reduction using nano-sized metals during thermal applications and found that metal nanoparticles significantly improved heavy oil and bitumen recovery rates.
Abstract: The efficiency of heavy oil and bitumen recovery methods can be increased by improving energy transfer to the oil for increased viscosity reduction. Studies have shown that micron-sized metal particles improve the efficiency of ex situ processes such as coal liquefaction and pyrolysis. This study investigated the mechanics of additional viscosity reduction using nano-sized metals during thermal applications. Experiments were conducted to investigate the exothermic chemical reactions and thermal conductivity of iron, nickel and copper particles. The viscosity of oil samples mixed with the particles was measured, and the tests were repeated at different temperatures. The effect of the metal particles on heat transfer enhancement was also investigated. The studies showed that the metal nanoparticles significantly improved heavy oil and bitumen recovery rates. However, the percentage of the viscosity reduction and the optimum concentration of metal nanoparticles was highly dependent on the oil sample composition and the metal type. Different types of metals reduced heavy oil and bitumen viscosity with different series of exothermic reactions. The thermal conductivity of the metal must also be considered. Further studies are need to determine reactions when the nanoparticles are introduced into reservoirs. 24 refs., 4 tabs., 7 figs.
TL;DR: In this paper, a comparative laboratory experiment was conducted to investigate the effectiveness of cementitious fillers on moisture susceptibility of hot-mix asphalt (HMA) mixtures, and the test results indicated that the cementitious filling agents were generally effective in reducing the moisture susceptibility.
Abstract: Moisture-induced damage has long been recognized as one of the major concerns for asphalt pavements. To mitigate potential moisture damage, one general method is to add mineral antistripping additives or liquid antistripping agents into hot-mix asphalt (HMA) mixtures. In this study, a comparative laboratory experiment was conducted to investigate the effectiveness of cementitious fillers on moisture susceptibility of HMA mixtures. Five types of cementitious fillers were considered: fly ash, cement kiln dust, and three types of hydrated lime with different finenesses. The laboratory performance of HMA mixtures subjected to moisture conditioning was evaluated through the following tests: dynamic modulus test; superpave indirect tensile tests; and tensile strength ratio test. The test results indicate that the cementitious fillers were generally effective in reducing the moisture susceptibility of HMA mixtures. The finer the hydrated lime particle, the more resistant the asphalt mixtures. In addition, dynamic shear rheometer test was conducted on asphalt mastics to explore the stiffening effect of different cementitious fillers.
TL;DR: A simple experimental procedure was developed in this paper to measure water vapor diffusion coefficients in coarse aggregates, fine aggregate mixture (blend of the fine portion of the aggregates with the asphalt binder), and hot-mix asphalt.
Abstract: Moisture damage in asphalt mixtures is defined as the gradual loss of structural integrity caused by the presence of moisture. A simple experimental procedure was developed in this study to measure water vapor diffusion coefficients in coarse aggregates, fine aggregate mixture (blend of the fine portion of the aggregates with the asphalt binder), and hot-mix asphalt. The procedure is based on periodic weight measurements of specimen-container ensembles subjected to a controlled temperature and relative humidity environment. Fick’s first law was used to estimate the diffusion coefficients of the materials. The results show that the proposed experimental method is an economic and efficient tool to quantify water vapor diffusion coefficients. Determining these material properties is fundamental to develop numerical models to study the deleterious effects of moisture vapor on the mechanical performance of asphalt mixtures. In order to exemplify the significance of the experimental measurements, a numerical si...
TL;DR: In this paper, the applicability of developing bio-binders from switchgrass bio-oil fractions to be utilized as a direct alternative has been investigated, and the relationship between viscosity and temperature and shear rate can be well described by Arrhenius-type and Power law models, respectively, or by a log linear relationship.
Abstract: An alternative approach for decreasing the demand and dependency for crude petroleum/bitumen binders is the use of bio-binders in three different ways: a direct alternative binder (100% replacement), a bitumen extender (25% to 75% replacement), or a bitumen modifier (10% replacement). In this paper, the applicability of developing bio-binders from switchgrass bio-oil fractions to be utilized as a direct alternative has been investigated. The results showed that the relationship between viscosity and temperature and shear rate can be well described by Arrhenius-type and Power law models, respectively, or by a log linear relationship. As an overall conclusion, the rheological properties of switchgrass bio-oils are similar and comparable to bitumen binders and represent a viable renewable alternative to petroleum derived asphalt binders.
TL;DR: In this article, a new theory is derived that takes into account the impact of oil saturation and relative permeability on the oil mobility profile at the edge of a steam chamber, and the results reveal that the higher the thermal diffusivity of the oil sand, the deeper the location where the oil phase velocity is maximum.
Abstract: The use of steam-assisted gravity drainage (SAGD) to recover bitumen from Athabasca deposits in Alberta has been growing. Butler [Butler, J. Can. Pet. Tech. 1985;24:42–51] derived a simple theory to calculate the production rate of oil during SAGD in an ideal reservoir. This simple and useful theory made several assumptions about the properties of the reservoir and operating conditions of the process. The theory also assumed that the highest mobility oil is at the edge of the steam chamber and that the oil phase velocity is highest at the chamber edge and reduces with distance into the oil sand. This research examines flow conditions at the edge of the steam chamber. Specifically, a new theory is derived that takes into account the impact of oil saturation and relative permeability on the oil mobility profile at the edge of a steam chamber. It is shown that the flow behaviour at the edge of a steam chamber is more complex and is not fully represented by Butler's theory. Contrary to Butler's theory, the oil mobility has its maximum some distance away from the edge of the steam chamber. The results reveal that the higher the thermal diffusivity of the oil sand, the deeper the location where the oil phase velocity is maximum. The developed model has been validated against published experimental and field data.