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The compatibility between waste plastic polymers and bitumen is the most challenging issue hindering the improvement of modified bitumen performance. The current practice of recycled waste plastics includes the use of polyvinyl chloride (PVC), polypropylene (PP), polyethylene (PE), etc. This study was designed to investigate the compatibility of different waste plastic polymers with bitumen binders by conducting molecular dynamics (MD) simulations at different temperatures. The molecular models of these materials were constructed in this study for the compatibility analysis, and they include the base bitumen, polymers (PVC, PP, and PE), polymer- bitumen blending systems. Using the output and related calculations of these MD models, the properties of these blending systems were measured at different temperatures through the calculation of the solubility parameter (δ) and interaction energies. The compatibility analysis is discussed in the context of these simulation results. The simulation results for the solubility parameters and interaction energies show consistent trends. The results showed that PVC and PP had better compatibility with bitumen at 433.15 K and that PE and bitumen had good compatibility at 393.15 K. Moreover, it can be deduced that the order of compatibility of the three polymers with bitumen is as follows: PVC > PE > PP. In addition, these research results can be referenced for the industry and research development of modified bitumen. [ABSTRACT FROM AUTHOR]

Styrene-butadiene-styrene (SBS) is widely used to improve the properties of the base bitumen and hence bituminous mixtures. As SBS modification induces cost increase, natural asphalts have become an important issue. In this study, the effects of gilsonite supplied from Iraq, a type of natural asphalt (NA) on conventional and rheological properties of bitumen, were investigated. NA was used 20%, 35%, and 50% by weight of bitumen. The properties of NA modified bitumen were compared to 2%, 3%, and 4% SBS modified bitumen. Conventional (penetration, softening point, rotational viscosity) and rheological (dynamic shear rheometer, bending beam rheometer) binder tests were conducted on base and modified bitumen. The index values representing together the workability, high and low temperature properties were defined by dividing the rutting parameter to viscosity and rutting parameter to low temperature stiffness. Overall, the test results show that 20% NA modified B160/220 bitumen exhibited similar performance with B160/220+3%SBS modification produced at 16% higher cost in terms of the high and low temperature properties. [ABSTRACT FROM AUTHOR]

The purpose of this work is to study the thermal stability of humic acids and bitumens extracted from brown coals of the Circumpolar Urals in the Khanty-Mansi Autonomous Okrug-Ugra. Waxes, bitumens and resins were extracted from brown coals with benzene on Soxhlet apparatuses. Extraction of humic acids was carried out by the Instorf method. Thermal analysis of all humic acid samples was performed at Novosibirsk Institute of Organic Chemistry in the Siberian Branch of the Russian Academy of Sciences on a STA 409 PC Luxx synchronous thermal analyser (Netzsch Company) in an inert atmosphere in a platinum crucible. It was found that thermal stability of humic acid macromolecules obtained from brown coals is characterized by typical thermal effects and quantitatively different value of macromolecule destruction within the ranges from 220 to 400 °C and from 400 to 800 °C. [ABSTRACT FROM AUTHOR]

The modifying effects of polymer on bitumen low-temperature performance are substantially compromised by the thermal breakdown of styrene–butadiene rubber (SBR) polymer during bitumen mixture production operations. The efficacy of the utilization of Sasobit/waste cooking oil (Sasobit/WCO) as a warm-mix additive has been demonstrated in mitigating the adverse consequences of thermal aging on SBR-modified bitumen binder (SB) while preserving the binder's original performance characteristics. However, few studies have been conducted to further investigate the rheological properties and aging resistance of SB modified with Sasobit/WCO compounds. In this work, three additives—Sasobit, WCO, and Sasobit/WCO composite—were selected, and their effects on the physical and rheological characteristics of SB as well as the temperatures at which the mixtures were prepared were assessed. In addition, by using dynamic shear rheometers (DSR) and bending beam rheometers (BBR), the effects of this innovative warm-mix addition on the performance grade (PG) and aging resistances of SB were evaluated. According to the results, Sasobit/WCO composites outperform Sasobit and WCO in lowering the mixture preparation temperature. Sasobit/WCO also improves both the high- and low-temperature performance of SB simultaneously. Compared to hot-mix asphalt mixtures, the addition of Sasobit/WCO reduces the preparation temperature of the bitumen mixtures by 19 °C, which in turn helps to minimize the negative effects of temperature aging on the functioning of the SB. Additionally, the Sasobit/WCO composite addition can improve the SB mixture's resistance to thermal cracking. After the introduction of Sasobit/WCO, the high-temperature PG of SB was raised by two levels, regardless of whether the warm-mix impact was taken into account. With the addition of Sasobit/WCO, SB's resilience to short-term aging was enhanced. [ABSTRACT FROM AUTHOR]

This paper presents a United Atom (UA) force field for simulating hydrocarbon molecules in bituminous materials, integrating explicit hydrogens into beads with their parent atom. This method simplifies all-atom molecular models, significantly accelerating Molecular Dynamics (MD) simulations of bitumen by 10 to 100 times. Key advantages include halving the particle count, eliminating complex hydrogen interactions, and decreasing the degrees of freedom of the molecules. Developed by mapping forces from an all-atom model to the centers of mass of UA model beads, the force field ensures accurate replication of energies, forces, and molecular conformations, mirroring properties like pressure and density. It features 17 bead types and 287 interaction types, encompassing various hydrocarbon molecules. The UA force field's stability, surpassing all-atom models, is a notable achievement. This stability, stemming from smoother potential energy surfaces, leads to consistent property measurements and improved stress tensor accuracy. It enables the extension of MD simulations to larger spatiotemporal scales, crucial for understanding complex phenomena such as phase separation in bituminous materials. This foundational work sets the stage for future developments, including refining parameters and introducing new bead types, to enhance the modeling capabilities of the force field, thereby advancing the application and understanding of bituminous materials.

An experimental investigation of an innovative recycling method to reuse dredged sludge in asphalt pavements is presented. According to this method, semifinished products or agglomerates, made of dried sludge and bitumen, are produced. These products may be used to partially substitute fine sand and bitumen in the asphalt mix. In this paper, the practical aspects of the manufacture, storage, and transportation of these agglomerates are simulated in order to demonstrate the feasibility of the method. The technical properties of asphalt mixes prepared with these new products are compared to those of a reference asphalt mix, in terms of Marshall characteristics, stiffness, complex modulus, permanent deformation, and water sensibility. Environmental and economic issues are also analyzed. A simplified cost factor analysis shows that this method is economically advantageous compared to the disposal of contaminated sludge. [ABSTRACT FROM AUTHOR]

This paper deals with the influences of phenol formaldehyde resin on the rheological properties of petroleum bitumen. Different amounts of phenol formaldehyde were doped into the bitumen of penetration grade and variations in viscosity as a function of temperature and additive concentration were determined. The effects of the phenol formaldehyde additive were examined by conventional and Superpave test methods. Adhesion and stability of bitumen aggregate mixtures prepared using pure and modified bitumen were compared using Nicholson stripping and Marshall tests. The appropriate dosage of the additive yielding the best rheological and performance properties in hot climates was found to be 2% (w/w). Appreciable decreases in the formation of rutting, bleeding, stripping, and cracking in bitumen may be obtained through phenol formaldehyde addition. [ABSTRACT FROM AUTHOR]

Permeability of open-graded asphalt mixes is defined as the ability to transmit fluids through the voids. The infiltration of water affects the durability and safety of pavement systems. Traditionally, an empirical approach, based on laboratory tests or on field measurements, is used to evaluate hydraulic permeability. In general, such an approach allows the ex post calculation of the drainage capability of the open-graded pavement. In order to evaluate the hydraulic permeability during the phase of mix design, in this paper a novel method is proposed, based on simulation of unsteady flow of water through open-graded mixture. In particular, a real sample of asphalt mix is simulated in the shape of a Marshall test sample. It is composed of a set of particles, selected according to the real grading, positioned in the space domain following the random sequence adsorption approach (RSA) and covered by a film of bitumen. The flow of water through the synthetical sample is simulated through the lattice Boltzmann method. In this method, the particles of water propagate and collide while moving on a lattice, obtained by discretizing the physical space. This lattice is formed by equidistant nodes, where each node corresponds to a void or to a solid. The velocity of the particles depends on a set of microscopic velocity vectors. Simulation results allow prediction of the permeability of open-graded pavement through a theoretical calculation based on the Kozeny-Carman equation. The model is validated using experimental tests. [ABSTRACT FROM AUTHOR]

In this paper, an attempt was made (through theoretical analysis) to solve the problem of fatigue life and strength of an asphalt material modified with crumb rubber. The authors used the developed earlier idea of the possibility of micro-cracks propagation retardation and their arrest in heterogeneous systems (Kaplan and Chekunaev (2010)). In this paper, the authors calculated size of crumb rubber particles significantly slowing down rate of microcracks conversion into macrocracks. It was shown that the most optimal size of bitumen modifier particles (crumb rubber) is ultra-small (200 - 600 nm). [ABSTRACT FROM AUTHOR]

Abstract: Canada's oil industry is a growing energy source, with proven reserves exceeding 174 billion barrels. The majority of the production is attributable to oil sands. Thermal bitumen extraction is the predominant production method, and is poised to grow at an annual rate of 23% to 2025. This has important long-term GHG emissions implications. To date, CO2 emissions mitigation efforts have overwhelmingly focused on implementing CCS in bitumen upgrading operations, rather than in thermal bitumen extraction processes. The paper covers the application of CO2 capture to the main thermal bitumen extraction process: SAGD (Steam-assisted gravity drainage). The paper presents four SAGD-oxy-fuel integration configurations and compares their techno-economics to a SAGD process featuring natural gas-fired co-generation without CO2 capture (reference case). Configuration one is a natural-gas fired co-generation boiler retrofitted for oxy-fuel operation. Configuration two is an oxy-fuel fluidized boiler using bitumen as fuel. The third configuration features a natural gas oxy-fuel boiler integrated with a cryogenic Air Separation Unit (ASU). The pressurized “waste” N2 is expanded in a turbine with additional heat integration. The fourth configuration features natural gas oxy-combustion with O2 from an Oxygen Transport Membrane (OTM) unit. Other integration concepts, including Chemical Looping combustion (CLC) are introduced. Because these concepts are in an earlier stage of development, the discussion covers their qualitative aspects and potential benefits over the previously mentioned cases. [Copyright &y& Elsevier]

There is a constant effort to improve the performance of asphalt-concrete (AC) mixtures. Among various modifiers for asphalt, fibers have received much attention for their improving effects. This paper introduces the novel concept of hybrid reinforcement of AC mixtures using polypropylene (PP) and glass fibers. Individually, glass fiber reinforced AC and PP fiber modified AC mixtures have exhibited superior performance compared to other fiber reinforced samples. Therefore, in this work, these two types of fibers were used simultaneously to improve the performance of the AC mixtures. This type of hybrid AC composite can be engineered by taking advantage of the tacky property of PP fiber around its melting point and the high modulus of glass fiber. In this way, PP fibers with the length of 12 mm were blended with bitumen at different percentages. Glass fibers with the length of 12 mm were also added to aggregates. Marshall and Specific Gravity tests were performed on hybrid reinforced asphalt-concrete (HRAC) samples by taking advantage of a Superpave Gyratory Compactor. In the case of the bituminous specimens, penetration, softening point and ductility tests were carried out. The results revealed that PP fibers decrease penetration and ductility of modified bitumen, while the softening point value is increased compared to unmodified bitumen specimen. Marshall Test results illustrate that PP can statistically affect the properties and improve the consistency of the mixture. Using a combination of 0.1% of glass fiber plus 6% of PP presented the best hybrid reinforcement through increasing stability and decreasing flow. Therefore, it is concluded that this novel HRAC is suitable for use in hot regions due to growth in the void total mix (VTM) and stability. [ABSTRACT FROM AUTHOR]

In this paper, an atomic force microscope (AFM) was used to study the nano-morphology characteristics of styrene-butadiene-styrene block copolymer (SBS) modified bitumen. The effects of SBS content and short-term aging on the nano-morphology parameters of bitumen were studied. The correlation between nano-morphology parameters and main pavement performances of SBS modified bitumen was analyzed. The results show that with the increase of SBS content, the average area of bee-like structure and the proportions of bee-like structure area of SBS modified bitumen increases gradually, the roughness of the whole image and the roughness of the lightweight component region decreases gradually, but the increasing or decreasing trend is no longer obvious when the content of SBS is more than 4%. The maximum height difference of SBS modified bitumen is linear with the content of SBS. The larger the content of SBS, the smaller the influence of short-term aging on the nano-morphology of SBS modified bitumen. The penetration degree will decrease and the softening point will increase with the increase of the proportion of bee-like structure area of SBS modified bitumen. The ductility will decrease with the increase of the roughness of the lightweight component region. The ductility and the Brookfield viscosity will increase with the increase of the maximum height difference. The research results provided a reference for defining quantifiable nano-parameters of SBS modified bitumen and establishing the relationship between nano-parameters and pavement performances. [ABSTRACT FROM AUTHOR]

Five types of material, styrene-butadiene-styrene block copolymer (SBS), ethyl-vinyl-acetate (EVA), naphthenic oil, maleic anhydride grafted ethylene-vinyl acetate copolymer (EVA-g-MAH) and butylated hydroxytoluene (BHT) were used as the raw ingredients for manufacturing direct-to-plant SBS in this paper. Thirteen kinds of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS were prepared as well as the processes diagrammatic sketch of dispersion and swelling of direct-to-plant SBS modifier in bitumen were discussed. Microscopic images of direct-to-plant SBS modified bitumen with different components were obtained using fluorescence microscopy. The micro-images were analysed and quantified with MATLAB software. The influence of key components on the micro-morphology of direct-to-plant SBS-modified bitumen is discussed, followed with the tests on melting points and the melting indexes of direct-to-plant SBS with different EVA/SBS and naphthenic oil/SBS. The performances test of bitumen and bituminous mixture modified by these direct-to-plant SBS were also conducted. Results show that, with the ratio improvement of EVA/SBS or naphthenic oil/SBS, the number of the pixel dot number of area (SBS) in microscopic images increased. Enlargement of the pixel dot number of centre line elongate and the structure fineness was observed, indicating that the dispersion and swelling effect of the SBS modifier in bitumen had been improved. Meanwhile, the macro index, such as the melting point and melting index of direct-to-plant SBS, was also improved corresponding to the increase of EVA/SBS ratio or naphthenic oil/SBS ratio. With the addition of EVA or naphthene oil content, penetration and ductility of direct-to-plant SBS modified bitumen received gradual enhancement, but the softening point and viscosity were found out to be decreased. The high-temperature and low-temperature performances of direct-to-plant SBS modified bituminous mixture can be effectively improved by adding EVA or naphthenic oil. By meeting the required performances of direct-to-plant SBS, modified bitumen and bituminous mixture, the component of direct-to-plant SBS is recommended as, SBS:EVA:naphthenic oil:EVA-g-MAH:BHT is 1:0.1–0.5:0.05–0.2:0.03:0.05. For the compatibleness of SBS with different bitumen are different, necessary tests verification is recommended to be carried out prior to usage. [ABSTRACT FROM AUTHOR]

Irrigation canals are primary hydraulic infrastructures from an agricultural point of view, and their performance is highly dependent on the efficiency and durability of their coatings. This paper presents the main conclusions of a survey undertaken in Portugal, which concluded that in most situations, the following technologies are used: concrete cast on site, precast concrete slabs, and prefabricated membranes (polymer bitumen or synthetic). These linings may manifest various pathologies with significant consequences on the amount of water lost as a result of lack of watertightness. These defects are classified by lining solution, and their main causes identified. Finally, an exhaustive set of recommendations and rehabilitation techniques are described to minimize water leakage from the canals. [ABSTRACT FROM AUTHOR]

A material exhibits thixotropic behavior if its apparent viscosity decreases under stress and if it recovers its initial viscosity when unloaded. This thixotropy is well defined for fluids, but it is not well understood for viscoelastic materials. For bituminous binders, it a priori corresponds to a decrease in material stiffness under cyclic loading and a recovery of this stiffness after rest. Rheological tests, in which the stress distribution in the material is simple and controlled, appear interesting to gain relevant observations concerning the thixotropic behavior of bitumens. The materials were tested under simple shear flows with the help of a controlled stress rheometer, and the influence of temperature, frequency, and conditioning time were studied. This paper proposes a new experimental procedure for studying binder thixotropy in cyclic mode by means of shear tests. The procedure relies on the observation of the breakdown curves in the nonlinear domain and modulus recovery curves at different frequencies and temperatures. Stiffness variations are demonstrated to be linked to a rearrangement of molecular structure and not to crack formation and healing. Moreover, fatigue performance appears better for the binder that shows the most important capacity to be destructured. [ABSTRACT FROM AUTHOR]

Plastic waste disposal is a serious and growing challenge to all major metropolitan areas around the world. If not disposed of properly, plastic waste can degrade in the environment for several years. This study investigated using recycled plastic bags in road construction. The purpose was to find a reuse for plastic waste and to improve road properties. Traditionally, bitumen is used in road surfacing and coating. Shredded plastic bags were mixed with bitumen in different ratios to determine which ratios could enhance road quality in terms of asphalt strength and durability. To identify the optimal plastic percentage content, Marshall stability, retained strength and stripping tests were applied using various of bitumen to plastic ratios. Results show that a bitumen mixture of 8% recycled plastic was the strongest and most durable for all tests. [ABSTRACT FROM AUTHOR]

Bitumen from Asbuton can be used as an alternative of oil or bituminous materials. This paper presents results connected with determination of the parameters of the water process of bitumen recovery. They include the process temperature, the concentration of sodium dodecyl benzene sulfonate (SDBS) as a surfactant and that of Na2CO3 as a sealing agent. The experiments carried out show that the recovery of bitumen increases with increase of the temperature and the concentration of Na2CO3. It increases with increase of the concentration of SDBS up to 0.375 %. The recovery of bitumen decreases with further increasing SDBS concentration from 0.375% to 0.5%. The highest percentage of recovery amounting to 91.92 % is obtained at 90°C in presence of 1 % of Na2CO3 and 0.375 % of SDBS. An optimization using the response surface methodology (RSM) was also carried out. The predicted optimal bitumen recovery condition refers to 1 % concentration of Na2CO3, 0.385 % concentration of SDBS and a digesting temperature of 89.99°C. These parameters values provide an optimal percentage of bitumen recovery of 89.78 %. The process temperature and Na2CO3 concentration are the significant terms of the model. The analysis of the variance (ANOVA) indicates that the model is significant as evidenced by R² value of 0.9589 and the model F value of 18.13. The percentage recovery of bitumen envisaged by the model is close to the value determined experimentally (80.683 % and 80.6825 %, respectively). This provides the conclusion that the model can be used for predicting the percentage of bitumen recovery from Asbuton using the hot water process method. [ABSTRACT FROM AUTHOR]

• Solvent-extracted bitumen was refined into fuels with and without upgrading. • Life cycle energy and greenhouse gas emissions were evaluated. • Energy consumption ranges between 0.74 and 1.03 GJ/bbl of bitumen. • Emissions range from 84.6 to 138.2 kg CO 2 eq./bbl of bitumen. • Fuels from solvent-extracted bitumen are less energy- and emissions-intensive. The vapor solvent extraction process is one of the newly proposed bitumen extraction methods that use less energy and emit fewer greenhouse gases than conventional approaches. Through life cycle assessment, this paper examines the energy requirements and associated greenhouse gas emissions of three pathways of producing transportation fuels from the solvent extraction process: delayed coking upgrading, hydroconversion upgrading, and direct refining processes. A Monte Carlo simulation was performed to determine the uncertainty in the model input parameters. The hydroconversion pathway was found to be more energy- and emissions-intensive (1.03 GJ/bbl and 138.2 kg CO 2 eq./bbl) than delayed coking upgrading (0.86 GJ/bbl and 92.3 kg CO 2 eq./bbl) and direct refining (0.74 GJ/bbl and, 84.6 CO 2 eq./bbl), but it offers a higher yield than delayed coker upgrading. Direct refining of bitumen from a vapor solvent extraction process reduces the overall life cycle emissions of transportation fuels. [ABSTRACT FROM AUTHOR]

Abstract This paper has been prepared in the frame of a research focused on the development of Cold Mix pavement materials made with calcium-alginate Capsules (CMC) instead of with just bitumen emulsion, as it is normally made. The initial objective was to remove most of the water in cold mix asphalt by encapsulating bitumen droplets. The encapsulation method allowed the preparation of polynuclear capsules with bitumen emulsion encapsulated, which membrane was made of calcium-alginate. Capsules were mixed with aggregates at the ambient temperature. During mixing, the capsules containing bitumen emulsion would break, release their content and coat the aggregates. To study CMC, an extensive experimental programme has been carried out to evaluate the effect of compaction energy, cement content, curing time and binder type on the mechanical properties of CMC. It was found that CMC test samples increased their Marshall stability linearly with the increase of the compaction energy. Test samples could be demoulded immediately after compaction. Furthermore, the Marshall stability of CMC increased with the curing time, and the general strength improved with the increasing amount of capsules in the mixture. It was found that the bitumen in CMC did not have an important role on the strength of the pavement material, which came mainly from the alginate in the capsules. In short, cold mix pavement materials made with calcium-alginate (Ca-alginate) capsules is a novel material for pavements that has shown potential to be an alternative for conventional cold mix asphalt made with bitumen emulsion. Highlights • Alginate and Portland cement have been tested as a new binder for pavements. • The materials could be mixed and compacted at the ambient temperature. • The mechanical stability of the new pavement material was evaluated. • The strength of the material was equivalent to that of a hot mix asphalt after 24 h curing. • The new material could be loaded by traffic after less than 24 h curing. [ABSTRACT FROM AUTHOR]

Abstract Vacuumable gels have been developed in the nuclear industry to decontaminate solid surfaces with little or no mechanical operations and without producing any liquid effluents. These gels can be spread on the contaminated surface and rapidly trap the radio-contaminants by sorption after corroding the substrate down to several tens of microns if necessary. The gel then dries and eventually fractures into a non-powdery solid that is easily removable by brushing or vacuum cleaning. This process was initially developed for the nuclear decontamination of metallic surfaces but innovative formulations are being developed for wide range of applications. This paper introduces two such formulations designed to remove sticky organic layers, bitumen in this study. We show that adding an organic bio-solvent, limonene, allows bitumen layers to be dissolved, absorbed in the liquid state into the gel matrix, and then removed from the substrate as solid waste after drying. Substituting an organic co-solvent (ethanol) for some of the limonene improves the overall efficiency of the process by decreasing the drying time of the gel and limiting the diffusion of the dissolved bitumen without affecting the dissolving power of the gel. Finally, the performance of these gels is demonstrated for the removal of nuclear contaminated (137Cs) bitumen stains. Highlights • Gels have been prepared using inorganic nanoparticles and organic solvents. • These gels are designed to remove bitumen stains without mechanical operations. • Adding ethanol to the gel improves the efficiency and efficacy of the process. • Radioactive 137Cs contamination in the bitumen is also removed. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Highlights • A new specimen was proposed for determining mixed mode fracture toughness of asphalt bitumen. • K Ic and K IIc values were obtained for 30/40 binder under different mode mixities, low temperatures and loading rates. • Shear mode fracture resistance value was less than the tensile mode fracture resistance in the tested bitumen. • The obtained results were predicted theoretically using the GMTS criterion. Abstract Crack growth in asphalt concretes or bitumen is a major failure mode at low temperature conditions. However, the vast majority of fracture toughness studies for such materials have been mainly performed on asphalt mixtures and the crack growth analysis and fracture behavior of pure and neat bitumen has rarely been studied in the past. Therefore, in this paper low temperature crack growth behavior of bitumen (with penetration grade of 30/40) is investigated experimentally using a new and novel test configuration called inclined notched bend beam (INBB) specimen. In order to investigate the effect of environmental conditions on the cracking response of bitumen, the fracture toughness experiments were performed at two temperatures of −15 and −25 °C and two loading rates of 10 and 50 mm/min. It was shown that the tested 30/40 bitumen behaves as a brittle material for the whole testing conditions and mode I and II mixities ranging from pure mode I to pure mode II. Empirical fracture toughness envelopes were then extracted for the tested bitumen to understand typical fracture resistance values for any desired mode mixity. It was observed that the fracture toughness value decreases by moving from pure mode I to pure mode II demonstrating weaker strength of bitumen against shear type fracture in comparison with the tensile one. The reduction of mode II and mixed mode I/II fracture toughness values relative to the K Ic was also predicted successfully by means of a well-known fracture condition. [ABSTRACT FROM AUTHOR]

Copyright of Ciencia e Ingenieria Neogranadina is the property of Ciencia e Ingenieria Neogranadina and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The True Boiling Point (TBP) analysis according to ASTM D-2892 standard is the single reliable tool for characterization of crude oil and petroleum mixtures in terms of their boiling point distribution. However, the analytical procedure is expensive and time consuming, which is inappropriate for quick estimation of crude oil distillation characteristics. Thirty three crude oil samples were characterized by means of TBP distillation and ASTM D-86. This paper presents an attempt to test the applicability of the major methods available in the open literature for converting ASTM D-86 to TBP for the whole range of the distillation curve. The whole distillation curve was obtained by using the Riazi's distribution model ((Ti-To)/To=[?T/?T.Ln( 1/(1-xi))]1/BT), which demonstrated high accuracy with r2 ≥ 0.99. All methods demonstrated lower accuracy in converting the ASTM D-86 into TBP than the reproducibility of the ASTM D-2892. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Engineering Geology & the Environment is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Nowadays warm mix asphalt (WMA) is recognized as a very competitive alternative to hot mix asphalt (HMA). This technology allows to obtain an excellent and environmentally-friendly material for road construction. This paper focuses on the effect of a reduced short-term ageing temperature on the binder behaviour and on the effect of WMA chemical additives on the performance of short-term aged binders. Three asphalt binders (one polymer modified bitumen combined with two WMA chemical additives) were aged through the rolling thin film oven test (RTFOT) at different temperatures (120, 130 and 163 °C). Conventional, rheological and chemical tests were used for characterising the binders. Lower ageing temperatures provided reduced oxidation, implying lower oxidative hardening but also reduced permanent deformation resistance. A general reduction of ageing effects is observed in the WMA binders, with both positive (moderate deceleration of the ageing process) and negative (more noticeable reductions in the permanent deformation resistance) outcomes. The microscopic analysis showed that the chemical additive likely alters the structural interactions of bitumen and polymer. A comparison between WMA binders short-term aged in laboratory and in field, indicates that the RTFOT performed at reduced temperature could properly simulate the field ageing when WMA production temperatures are considered. Graphical abstract Unlabelled Image Highlights • Chemical additives tend to reduce the effect of short-term ageing on binder performance. • Chemical additive type and ageing temperature affect the binder recoverable behaviour. • The structural interactions of bitumen and polymer are altered by the chemical additives. • Short-term ageing at reduced temperature properly simulates field ageing of warm mix asphalts. [ABSTRACT FROM AUTHOR]

Abstract The paper describes work to design, build and test an asphalt 3D printer. The main difficulty encountered is that asphalt behaves as a non-Newtonian liquid when moving through the extruder. Thus, the rheology and pressure in relation to set temperature and other operational parameters showed highly non-linear behaviour and made control of the extrusion process difficult. This difficulty was overcome through an innovative extruder design enabling 3D printing of asphalt at a variety of temperatures and process conditions. We demonstrate the ability to extrude asphalt into complex geometries, and to repair cracks. The mechanical properties of 3D printed asphalt are compared with cast asphalt over a range of process conditions. The 3D printed asphalt has different properties from cast, being significantly more ductile under a defined range of process conditions. In particular, the enhanced mechanical properties are a function of process temperature and we believe this is due to microstructural changes in the asphalt resulting in crack-bridging fibres that increase toughness. The advantages and opportunities of using 3D printed asphalt to repair cracks and potholes in roads are discussed. Graphical Abstract Highlights • We have created a technique to 3D print asphalt — we believe it is the first of its kind. • 3D printed asphalt is more ductile than cast asphalt. • The changes in mechanical properties are related to the microstructural changes in asphalt that occur during 3D printing. • The mechanical properties of 3D printed asphalt depend on process conditions, this can be advantageous allowing toughness to be tailored to the repair. • The technique has the potential to be used on autonomous vehicles or drones to autonomously repair roads and complex infrastructure. [ABSTRACT FROM AUTHOR]

A novel construction unit (Bitublock) composed entirely of recycled and waste aggregates and bound with bituminous binders is currently being developed. At present, the manufacturing process requires the new units to be heat cured to convert the bitumen binder from a viscoelastic material into an elastic-brittle material (known as hardening or bitumen aging). The paper investigates the effect of aging and curing processes on the compressive strength of Bitublocks. In this investigation, samples were compacted at pressures of between 8 and 20 MPa and cured at temperatures of between 60 and 160°C for up to 48 h. Compressive strengths approaching 45 MPa were achieved. The range of compressive strengths achieved indicated that the behavior of the bituminous binder during heat curing significantly influences the performance of the Bitublocks and suggested that bitumen hardening is highly influenced by the curing temperature. Oxidation as opposed to polymerization and loss of volatiles was confirmed to be the key role in the bitumen hardening process (only approximately 7% of the total long-term hardening was due to volatilization). The oxidation process can be directly linked to the compressive strength development of Bitublock. [ABSTRACT FROM AUTHOR]

The mechanochemically devulcanized ground tire rubber (m-GTR) prepared by solid-state mechanochemical reactor was used in the modification of bitumen with styrene-butadiene-styrene block (SBS) copolymer powder. The conventional properties (such as penetration index, softening point, 5°C ductility, and aging test) and rheological properties of bitumens modified by 8, 10, and 12 wt %m-GTR/SBS were investigated in this paper. The conventional properties except penetration of m-GTR/SBS modified bitumen were improved, compared with 5.5 wt % SBS modified bitumen. Rheological data demonstrated that all of the testing results of 10 wt %m-GTR/SBS modified bitumen were better than those of SBS modified bitumen under the condition of high temperature. The scanning electron microscope observation of the fractured surfaces showed that the m-GTR/SBS mixed powder had a better interface adhesion with matrix than SBS. [ABSTRACT FROM AUTHOR]

Polymers are widely used to improve the mechanical performance of asphalt mixtures. Among them, styrene butadiene styrene (SBS) is the most commonly used, especially in the wet modification of virgin bitumen. This method, which is extensively utilized, has several advantages, but also some disadvantages, concerning its performance (such as the risk of instability or a lack of homogeneity) and logistical management (such as the need for special equipment, the transport of materials, and the dependence on the refinery that modifies the bitumen). This paper analyses the use of the most conventional types of polymers (two types of SBS, one type of BS, and rubber from end-of-life tires), dry added, as an alternative method. They have been used in porous asphalt mixtures. This type of bituminous mixture is usually designed with commercial polymer-modified bitumen, due to the mechanical requirements, and it is very sensitive to the properties of the binder used. The mechanical behavior of experimental porous asphalt mixtures has been significantly improved, especially in the case of SBS, although the performance did not reach that of commercial polymer-modified bitumen. The results have shown that the dry method is a suitable and feasible option to manufacture modified mixtures, especially considering its advantages, from a logistical viewpoint, in comparison with the wet method. [ABSTRACT FROM AUTHOR]

The adopted TD–GC–MS/O method helps determine the correlation between the odour signals and compounds separated on the chromatographic column, from the analysed gas mixture. It is possible to compare the retention times at which the odour signals were identified with the retention time of eluting compounds, when the test system and matrix are known. The presented study describes the details of representative samples obtained from (1) indoor air samples from a room where floor materials containing bitumen are present, (2) wooden floor staves placed in an emission chamber, and (3) fragments (chips) of the materials mentioned above, placed in glass tubes, exposed to an elevated desorption temperature. The results, presented in the paper, describe the identified odours and their intensity and assign chemical compounds to each odour, indicating their likely source of origin. The results presented in the manuscript are intended to show what methodology can be adopted to obtain intense odours from the tested samples, without losing the sensitivity derived from GC–MS. The manuscript presents representative results—case studies. The results for various types of samples were not very reproducible, related to the complex matrix of bituminous products. The enormity of compounds present in tar adhesives makes it possible to indicate only the groups of compounds that emit from these systems. They include, primarily, aliphatic, aromatic and heteroaromatic hydrocarbons, particularly Naphthalene and Phenol derivatives. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemical Engineering is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Chemical Engineering is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Undertaking a chronic inhalation study on bitumen fume presents a challenge in terms of generating sufficient amounts of representative fume. The objective of the study described in this and in previous publications was to collect sufficient fume and use this to develop a laboratory-generated exposure atmosphere, for use in chronic inhalation toxicity studies in rats that resembles, as closely as possible, personal exposures seen in workers during road paving operation. To achieve this goal, atmospheric workplace samples were collected at road paving work sites and compared with bitumen fume condensate samples collected from the headspace of hot bitumen storage tanks. In Parts 1 and 2, we described the collection and analysis of workplace samples, the strategy for in-line extraction of a suitable fraction of bitumen fume collected from the headspace of a bitumen storage tank and the comparison of the collected condensate to the workplace samples. This paper (part 3) describes the regeneration of bitumen fume for inhalation and the exposure setup used for inhalation studies. [ABSTRACT FROM PUBLISHER]

Objectives: The objective of the study described in this and an accompanying series of papers was to develop a laboratory generated exposure atmosphere to be used for chronic inhalation toxicity studies in rats that resembles, as closely as possible, personal exposures seen by workers during road paving operations. [ABSTRACT FROM PUBLISHER]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Wax crystallisation and melting in bitumen is usually considered detrimental to bitumen quality and asphalt performance. The objectives of this paper are to study wax morphology in bitumen and to investigate effects of time, temperature, and thermal cycling on wax crystallisation. Various samples were selected, including eight waxy bitumens of different sources and three laboratory blends prepared by adding a slack wax and two isolated bitumen waxes to the non-waxy bitumen. Test methods used were differential scanning calorimetry (DSC), polarised light microscopy (PLM), confocal laser scanning microscopy (CLSM), and freeze etching (fracture) in combination with transmission electron microscopy (FF-TEM). The DSC results indicated that the selected bitumen samples differ widely in wax content and wax crystallisation starting and melting out temperatures. It was found that non-waxy bitumen displayed no structure or crystals neither in PLM, CLSM or FF-TEM, while waxy bitumens from different crude origins showed a large variation of structures. The morphology of wax crystals was highly dependent on crystallisation temperature as well as temperature history. The wax which has been isolated from waxy bitumen and mixed into non-waxy bitumen displayed similar morphology as the wax in the original bitumen. It was also found that bitumen wax usually melted at temperatures lower than 60°C although in one case a temperature of 80°C was needed until complete melting of the wax. [ABSTRACT FROM AUTHOR]

Asphalt is a common material that is used extensively for roadways. Furthermore, bituminous mixes have been used in railways, both as asphalt and as mortar. Different agencies and research institutes have investigated and suggested various applications. These studies indicate the benefits of bituminous material under railways, such as improving a substructure’s stiffness and bearing capacity; enhancing its dynamic characteristics and response, especially under high-speed train loads; waterproofing the subgrade; protecting the top layers against fine contamination. These potential applications can improve the overall track structure performance and lead to minimizing settlement under heavy loads. They can also guarantee an appropriate response under high-speed loads, especially in comparison to a rigid slab track. This review paper documents the literature related to the utilization of asphalt and bituminous mixes in railway tracks. This paper presents a critical review of the research in the application of asphalt and bituminous mixes in railway tracks. Additionally, this paper reviews the design and construction recommendations and procedures for asphalt and bituminous mixes in railway tracks as practiced in different countries. This paper also provides case studies of projects where asphalt and bituminous mixes have been utilized in railway tracks. It is anticipated that this review paper will facilitate (1) the exchange of ideas and innovations in the area of the design and construction of railway tracks and (2) the development of unified standards for the design and construction of railway tracks with asphalt and bituminous mixtures.

This paper investigates the reinforcement mechanism of bitumen mixed with fibers. Fibers including cellulose, rock wool and polyester types were added to bitumen. The viscosity, toughness and tenacity, microscopy and rheological tests were conducted to characterize the engineering properties of bitumen-fiber mastics. Test results indicate that the reinforcing effect increases with increasing fibers up to a critical fraction. With higher mixing temperatures, there is a higher viscosity ratio of mastic to bitumen. The tensile strength of bitumen-fiber mastics also increases with increasing fiber concentrations because the fibers carry parts of tensile loads. With the increasing tensile strength, it is implied that there is a good adhesion between bitumen and fibers. Scanning electron micrographs show that fibers reinforce bitumen through a three dimensional structure. However, there is a critical fiber fraction when fibers start to interact with each other, resulting in lower toughness. The optimum fiber content is dependent on fiber type, length and diameter. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemical Engineering is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Journal of Chemical Engineering is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper describes the polymer modification of road bitumens with SBS. Six polymer modified bitumens (PMBs) were produced by mixing bitumen from two crude oil sources with an SBS copolymer at three polymer contents. The rheological characteristics of the SBS PMBs were analysed by means of dynamic mechanical analysis using a dynamic shear rheometer (DSR). The results of the investigation indicate that the degree of SBS modification is a function of bitumen source, bitumen-polymer compatibility and polymer concentration. When the polymer concentration and bitumen-polymer compatibility allow a continuous polymer network to be established, modification is provided by a highly elastic network which increases the viscosity, stiffness and elastic response of the PMB, particularly at high service temperatures. However, ageing of the SBS PMBs tends to result in a reduction of the molecular size of the SBS copolymer with a decrease in the elastic response of the modified road bitumen. [ABSTRACT FROM AUTHOR]

The relaxation behavior affected by aging and rejuvenation plays a crucial role in its low-temperature cracking potential of bitumen. However, there are limited studies on the relaxation performance of rejuvenated bitumen under different rejuvenation conditions. This paper aims to propose critical indicators to assess the rejuvenation efficiency of low-temperature relaxation performance of various rejuvenated binders. The effects of rejuvenator type/dosage and aging level on relaxation parameters are investigated. The τ 50s , t 25% , and A are recommended as critical indicators based on their high sensitivities to influence factors and rejuvenation percentage scope. Additionally, molecular dynamic simulation outputs on virgin/aged bitumen and rejuvenators explain the difference in rejuvenation effectiveness of different rejuvenators. The results show that bio-oil rejuvenator exhibits the highest efficiency on regenerating the relaxation performance. All relaxation parameters of aged bitumen can be regenerated by adding rejuvenators. MD simulations reveal that the molecular mobility and free volume ratio of rejuvenators mainly cause the difference in rejuvenation efficiency on the relaxation property between various rejuvenators. The diffusion capacity of rejuvenator shows a more dominant effect on rejuvenation efficiency than fractional free volume. [Display omitted] • Rejuvenator type/dosage and aging level influence on relaxation performance of bitumen is explored. • The critical relaxation parameters for rejuvenation efficiency evaluation are compared and proposed. • The relaxation model parameters reflect the rejuvenation effectiveness on low-temperature performance. • Molecular simulation outputs explain the underlying mechanism on relaxation behavior difference. [ABSTRACT FROM AUTHOR]

The ethylene-vinyl acetate (EVA) polymers are always doped into waxy bitumen to inhibit network of wax crystals in bitumen. However, the compatibility improvement behaviors between wax-based warm mix (WWM) additives and bitumen by EVA are not clear, and the sustainable components of EVA for corresponding WWM additives to achieve better compatibility improvement are also not determined. This paper investigated compatibility improvement behaviors between commonly used WWM additives and bitumen after the addition of EVA to obtain sustainable components of EVA through experimental method of activation energy of viscous flow (AEVF) and density function theory-molecular dynamic (DFT-MD) calculations. The results show that the repulsions between the end of main-chain with highest electronegativity in WWM additives and polar molecules of EVA can alleviate the aggregation behaviors of WWM additives and EVA displays the best and worst compatibility improvements for additives with shortest and longest carbon chains, respectively. The dispersed asphaltenes combined with EVA can form the composite wax inhibitors (WIs) systems to increase diffusion coefficient and reduce percentage increment values of cohesive energy density (CED) to further disrupt ordered degree of WWM additives. On this basis, the sustainable carbon numbers of main-chain for EVA that are slightly less than average carbon numbers of WWM additives will help to better improve the compatibility of WWM additives. This investigation can provide the inspiration on how to choose the sustainable components of EVA to achieve high-efficiency compatibility improvement for corresponding warm mix asphalts (WMAs) with different average carbon numbers. [Display omitted] • The compatibility of WWM additives with virgin bitumen was characterized by AEVF method. • The atom charges distribution of WWM additives and EVA monomer were calculated by DFT. • The molecular models of WWM additives-asphaltenes- EVA -solvent system were established. • The crystallization and compatibility improvement behaviors of WWM additives were investigated. • The sustainable components of EVA for corresponding WWM additives were determined. [ABSTRACT FROM AUTHOR]

This paper introduces the maximum and minimum pavement temperatures of Estonian asphalt pavements in accordance with calculation models developed for North America and Norway. Historical meteorological data from 1992 to 2021 obtained from 25 different weather stations in Estonia were used as an input for the respective models. Comparison between the calculation models demonstrated high variability of the pavement design temperatures, thus significantly impacting the bitumen grade selection. Based on the road weather stations data, the Norwegian and Canadian models provide the most accurate pavement temperature estimations for Estonian conditions. Calculated upper and lower-bound pavement design temperatures varied between +52 °C to +58 °C and −22 °C to −34 °C, respectively. All models showed milder pavement temperatures and lower seasonal temperature amplitudes for coastal and offshore areas. The results also indicated the importance of validating model suitability as well as correlation with actual pavement temperatures in the Baltic region.

This paper describes results from a laboratory investigation into the effects of the interaction between a styrene-butadiene-styrene (SBS) modified bitumen and recycled crumb rubber on the mechanical performance of impact absorbing asphalt (IAA), an asphaltic material that has applications as a sports and safety surface. Curing tests at high temperatures have been undertaken using different rubber-bitumen ratios to assess the amount of bitumen absorbed by the rubber. The changes in bitumen constitution through this interaction have been monitored and related to changes in the rheological characteristics of the residual bitumen. The results show that significant absorption takes place and that the residual bitumen undergoes alterations in terms of its stiffness and viscoelastic balance, together with a reduction in cohesion. A significant finding has been the loss of the polymeric nature of the residual SBS polymer modified bitumen. This has been due to the precipitation of the SBS polymer as the compatibility between the base bitumen and polymer has decreased following the absorption of the lighter, solvating fractions of the binder. To assess the effect of the rubber-bitumen interaction on the mechanical durability of IAA, an abrasive wear test has been developed to simulate the contact between a twisting foot and the surface. This test has been used to compare the mechanical durability of laboratory prepared specimens that have been artificially aged at high temperatures (to simulate the mixing and transportation period before the material is laid and compacted). Results show that there is a detrimental effect on the mechanical durability of the aged material due to the interaction between the rubber and the bitumen. [ABSTRACT FROM AUTHOR]

During the hot application of bitumen-containing materials, e.g. in road paving or roofing, fumes are emitted that contain traces of polycyclic aromatic compounds (PACs). Although worker's exposure to these fumes is low, it might lead to health problems. For studying DNA adduct formation as a consequence of inhalation of bitumen fumes we developed and validated an inhalation system (a dynamic fume generator plus a nose only inhalation chamber). This paper presents and discusses the analytical results from the different laboratories involved in this study on the fumes sampled in the inhalation chamber during three series of experiments where the animals were exposed to fumes at the 5 mg/m3 and 50 mg/m3 level, coming from bitumen heated at 200°C and, as a positive control, fumes from coal tar, heated to 110°C at the 5 mg/m3 level. The following parameters were controlled: temperatures at different key places in the generator; humidity of the chamber; the bitumen or coal tar flow rate; and Total Particulate Matter (TPM). Analyses were performed for Benzene Soluble Matter (BSM), the EPA polycyclic aromatic hydrocarbon (PAH) mixture and for a number of heteroatom-containing PACs. The data show that the coal tar fumes produced at 110°C were very volatile and that most of the differences in particulate matter found between the laboratories can be attributed to evaporative losses. The bitumen fumes boil 25-50°C higher and contain higher boiling compounds. A comparison is made between the PAC exposure profiles for bitumen experiments aimed at 5 and 50 mg/m3. Although the same molecules are found in both fumes their proportion is dramatically different. This effect is largest with the 2- and 3-ring PACs, the ratio of the concentrations found in the 50 mg/m3 TPM concentration to that in the 5 mg/m3 experiment gradually declines from 5500 for acenaphthene to 500 for pyrene, for the 5-ring PACs this ratio is 20-30. As function of their vapour pressure, the ratios of the concentrations of the hetero PACs follow the same trend as that of the 16 EPA PAHs and are of the same order of magnitude. In conclusion, for the compounds investigated, the equipment delivers a fume atmosphere in a reproducible manner. The 50 mg/m3 bitumen fumes are not representatives of field fumes. The reason for these quantitative differences is unclear and further work would be needed to clarify this. Nevertheless it was felt that these fumes at 50 mg/m3 might be a useful tool for qualitative detection of DNA adducts in an animal exposure study. [ABSTRACT FROM AUTHOR]