Asphalt Content Research Articles

Poisson's ratio testing method and multi-factor influence quantification model of asphalt pavement materials

The current standard in China does not specify the standard test method for determining Poisson's ratio, and the Poisson's ratio used in pavement design is often roughly fixed, which can result in large errors in the calculations and analysis of road structure. In this paper, the research on different test methods for Poisson's ratio is carried out and the non-linear characteristics of tensile and compressive Poisson's ratio on pavement materials under different influencing factors are analyzed. The results indicate that the absolute value of the ratio between transverse rebound strain and longitudinal rebound strain under 50% of the maximum destructive load can objectively characterize the mechanical properties of Poisson's ratio, and it is the optimal measurement method for Poisson's ratio in asphalt pavement materials. The Poisson's ratio of two pavement materials both decreases with the increase of loading rate and gradually tends to a constant value. Cement dosage and temperature are the most significant factors affecting the tensile and compressive Poisson's ratio of cement stabilized crushed stone and asphalt mixture, respectively. Specifically, when cement dosage increases by 1%, the Poisson's ratio of cement stabilized crushed stone decreases by approximately 10%, and the temperature has a significant influence on the difference in tension and compression for Poisson's ratio of asphalt mixture (up to 40%). The asphalt content corresponding to the minimum Poisson's ratio is basically consistent with the optimal asphalt content obtained by the Marshall volume method. Based on these, a quantification value-taking model is established of the tensile and compressive Poisson's ratios of typical asphalt pavement materials varying with multiple factors. The research results can serve as a reference for the scientific value-taking of pavement structural design parameters considering the different mechanical characteristics of materials in tension and compression.

Development of Rainwater Filtration System with Porous Asphalt

Rainwater that is not properly collected causes stagnant water, where the water will be polluted by pollutants and contaminants. Thus, it is necessary to innovate to increase the availability of clean water using porous asphalt which is researched to reduce pollutants in polluted water. In this study, filtration of rainwater and stormwater runoff will be carried out using porous asphalt as a filter media with six different filtrate variations. Parameters analysed were pH, Total Dissolved Solids (TDS), and conductivity. The tests carried out were Optimum Asphalt Content (OAC) testing using the Marshall test method with a percentage of asphalt content used was 4-6%, Cantabro Loss testing, porosity, and permeability tests on porous asphalt specimens, as well as testing the filtration effect of porous asphalt. Rainwater and stormwater runoff that flowed through porous asphalt samples without the addition of filter media increased pH, TDS, and conductivity. In rainwater and stormwater runoff filtration, the highest increase in pH occurred in variation 3, namely porous asphalt + aggregate + limestone. The largest reduction in TDS and conductivity values occurred in Variation 7, namely porous asphalt + aggregate + coconut shell activated carbon + sponge + cotton.

Interfacial Interaction and Fatigue Behavior of Asphalt Mastics

Rheological characteristics of five road bitumens with different group composition and penetration at 25оС from 60 to 115х0.1 mm and asphalt binders based on them with volume content of filler (mineral powder of MP1 grade) – 0.275 (mass ratio bitumen: filler – 1:1) have been determined in the range from 30 to -10оС on dynamic shear rheometer. The influence of temperature and frequency on the parameter of interfacial interaction K-B-G* and thickness of adsorbed layer of original and thermal oxidative aging samples of asphalt mastic has been investigated. It is shown that in all samples K-B-G* decreases with decreasing temperature and increasing test frequency. A decrease in K-B-G* and adsorbed layer thickness in mastics after aging was observed in the case of bitumen with Gestel colloidal index CI=0.46–0.53, defined as CI=(S+A)(/R+Ar), and was stability of K-B-G* and adsorbed layer thickness in the case of bitumen with CI=0.61. No relationship was found between group chemical composition of bitumen and adsorbed layer thickness in original mastics. In aged mastic the greater thickness of adsorbed layer has samples based on bitumen with higher content of asphaltenes. The peculiarities of fatigue behavior of bitumen and mastic in the linear amplitude sweep test were investigated. The correlation between the thickness of the adsorbed layer and the angle of slope of the curves of dependence of the maximum shear stress (τmax) on the complex modulus (G*) was noted for aged samples.

The Usage of Additives on Porous Asphalt

Roads are an important infrastructure component, but often face problems such as changes in temperature, humidity, and standing water. To overcome this problem, a layer of porous asphalt which has air voids to reduce standing water on the road surface can be a solution. However, although porous asphalt has water-related benefits, its structure is less durable and requires increased resistance. Therefore, this study aims to analyze the effect of adding additives on the strength, permeability, and porosity of porous asphalt. Three types of additives studied were crumb rubber (CR), nano silica (NS), and Wetbond-SP. Several laboratory tests were conducted on the prepared specimens, namely the Marshall, Cantabro Loss, and permeability tests. The results showed that adding NS onto the specimen was able to increase the stability value of porous asphalt, while the addition of CR and Wetbond-SP had no significant effect on the stability parameter. However, the addition of Wetbond-SP improved the adhesion between the aggregate and asphalt, resulting in a denser mixture. The three additives also increased moisture resistance and cohesion loss in the mixture, as indicated by a decrease in Cantabro Loss (CL) percentage. Additives also impact the permeability and porosity values, where adding more additives in the mixture will reduce the permeability and porosity values. Based on the results of the study, the optimum concentration of CR added was 1% of the total weight of the mixture, NS was 4% of the weight of asphalt content, and Wetbond-SP was 0.4% of the weight of asphalt content.

Analysis Stability Of Asphalt Concrete Binder Course (AC-BC) With Fly Ash And Bottom Ash Substitution Material

Fly ash and bottom ash are ash produced from the process of burning coal as a source of energy in the steam generating unit of a coal-fired power plant (PLTU). Bottom ash is ash that forms at the bottom of a coal-burning furnace and settles there. In this research, fly ash is used as filler substitution and bottom ash is used as fine aggregate substitution (sand). The purpose of the study was to obtain a suitable Job Mix Design (JMD) for Asphalt Concrete - Binder Course (AC-BC) with fly ash and bottom ash substitution materials. To determine the effect of optimum asphalt content on the values of stability, flow, Marshall Quotient, VMA, VIM and VFB obtained from result of the Masrhall test. Based on the results of Marshall testing, the results show that Analysis Stability Of Binder Course Asphalt Concrete (AC-BC) With Fly Ash And Bottom Ash Substitution Material produces the highest VMA value of 14.462% and the highest VIM value of -1.88%, meaning that there are many gaps in the mixture containing asphalt so that it becomes waterproof and hermetic. The highest stability and MQ values are stability of 1955.55.34 kg and MQ of 1241.13 kg/mm. The appropriate Job Mix Design (JMD) for Asphalt Concrete - Binder Course (AC-BC) with fly ash and bottom ash substitution materials is the composition of Fly Ash at 0%, 50%, and 60% of the total cement while for the use of Bottom Ash from the total sand at 0%, 50%, and 60%.

Recovery of oil viscosity values according to its additive parameters

Considering the complexity of mixtures formed within extensive and intricate pipeline networks, determining the viscosity of mixtures through a computational method that utilizes parameters conducive to additivity is advantageous. These parameters may include the density and component composition, as well as corresponding derivatives, such as the content of paraffins, resins, asphaltenes, and fractional composition. This study explored the relationship between the viscosity and these parameters. A linear regression model for estimating the logarithm of the viscosity was developed, where significant regression coefficients were identified, and the prediction error was assessed through cross-validation. A similar approach was adopted for the second-order regression analysis. This analysis incorporated linear regression including parameters pertaining to the fractional composition. Formulas for calculating the viscosity based on the identified properties were derived and the respective errors were evaluated. Keywords: oil; viscosity; Arrhenius formula; cross-validation; paraffin; resins; asphaltenes; database.

Alterations in paraffin wax crystal networks induced by asphaltenes and pour point depressants, investigated by atomic force microscopy

Wax crystallization in pipelines in cold environments is a key factor affecting flow assurance during crude oil production. Polar crude oil components, such as asphaltenes, and polymeric pour point depressants (PPDs) have been demonstrated to interact with wax during gelation and crystallization through complex formation during nucleation or crystal growth alteration which leads to co-crystallization. This study introduces a methodology based on atomic force microscopy (AFM) to characterize features of solid surfaces precipitated from model wax, wax-PPD, wax-asphaltene and asphaltene systems. Height data collected from AFM measurements enabled the quantification of modifications in crystal sizes and shapes induced by the presence of asphaltenes and PPDs. The 2D Fourier transform of the height was used to generate statistics for the frequency of height amplitude, revealing information about the pore size and the height patterns. A stiffness/elasticity analysis was used to calculate the Young Modulus of the upper layers. In wax and wax-asphaltene systems, two nano-scale layers with different Young Modulus profiles emerged. The nano-scale layer on the top was softer and corresponded to more amorphous wax crystal networks with trapped dissolved wax. The nano-scale layer on the bottom was stiffer, comprising of more crystalline structures, corresponding to wax crystals with lower deviations from full crystallinity, with properties independent of asphaltene concentration. A bilayer did not form in the presence of PPD, which prevented the formation of amorphous phases with trapped dissolved wax or gel. After a methodology for model systems was established, the focus moved to systems based on production wax i.e. recovered from deposits. This was complemented by a comparison between model precipitation conditions and precipitation by cold finger, resembling industrial processes. Results highlighted the effect of change in chemical composition on topography, elasticity and adhesion of the surface. AFM provided new insights into wax crystallization patterns in the presence of inhibitors, which can be used to quantify the extent of wax-inhibitor interactions and project it on production systems. The method could be used to explain macro-scale rheological properties of oils during flow assurance in the future.

The effect of Polyethylene Terephthalate (PET) plastic addition to AC-WC in a wet mixture on increase of asphalt stability

PET (Polyethylene Terephthalate) plastic is one of the most common types of plastic used in Indonesia. Its existence has contributed significantly to various sectors, including the food and beverage, cosmetic, pharmaceutical, and other consumer product packaging industries. However, the use of PET plastic also creates a number of impacts that need to be considered. PET (Polyethylene Terephthalate) plastic has become an attractive alternative in the construction industry in Indonesia, particularly in its use as an asphalt mixture in road construction. This study aimed to determine the effect of the addition of PET waste to the asphalt on the value of Marshall characteristics as well as the optimum asphalt content and plastic content in the AC - WC mixture. Basic testing of 4 %, 5 %, and 6 % (by weight of asphalt) PET plastic mixture with wet mixing method where PET plastic is put into hot asphalt and stirred until homogeneous. Marshall test data will go through Formality Test, Homogeneity Test, Two-Way ANOVA, Duncan Test, and Correlation Regression Analysis to get the 3D graph equation. The result is that PET plastic affects the asphalt mixture by increasing the stability value and MQ value, for flow, VFB, and VMA values have decreased. VIM value increased at 4 % level and decreased at 6 % level. From the ribbon graph, the optimum asphalt content for each percentage of PET content is obtained, namely 4 % PET KAO value of 6.2 %, 5 % PET KAO 6.25 %, and 6 % KAO 6.28 %. It can be concluded that the mixing of PET with asphalt in AC-WC mixtures can be maximum if the right percentage combination of asphalt and PET content. From the 3D Graphic Method, it results that the maximum use of plastic PET is at a content of 5.40 %, and an asphalt content of 6.35 %, will produce an asphalt stability of 1714.232 kN

Investigating the Dynamic Creep and the Tensile Performance of Zeolitic Tuff-modified Warm Asphalt Mixtures

Aims This research investigates the effect of adding natural Jordanian Zeolitic tuffs to the SUPERPAVE asphalt mixture at the dynamic creep and the indirect tensile performance. Background Rutting and fatigue are considered the most common types of distress that affect pavements all over the world. Many factors can affect these properties, such as different aggregate properties, asphalt grades, and properties, as well as the type and amount of the mineral filler. Mineral fillers play an important role in enhancing the asphalt mixtures' performance by filling the voids in the mixture besides improving the cohesion of the binder as it has a small weight in addition to a very large surface area. Generally, the powder of limestone is the most used type of filler. However, studies showed that many materials could also be used as mineral fillers successfully. The focus of this study is using natural Jordanian Zeolitic tuff as a mineral filler. Jordanian zeolitic tuff mainly consists of Phillipsite, chabazite, and faujasite, which are considered the most abundant Zeolitic tuff minerals. The pyroclastic material is widely distributed in the Badia region of northeast Jordan. Zeolitic tuffs are located in Jabal Aritayn (30km northeast of Azraq), Tlul AlShahba (20 km east of Al Safawi), Tal Al-Rimah (35 km northeast of Al Mafraq), and other small deposits in central and south Jordan. Objectives The aim of this research was to study the impact of Zeolitic tuffs on overall Superpave asphalt mixture performance. Methods The specimens were prepared using the optimum asphalt content obtained by the SUPERPAVE method. Dynamic Testing System DTS-16 was used to apply both dynamic creep and indirect tensile tests that give a good idea about the rutting and fatigue behavior of asphalt mixtures. Both tests were conducted at 25 °C. Results The Zeolitic tuffs modified asphalt mixtures have lower accumulated strains and higher creep stiffness compared to the control mixture. Subsequently, the indirect tensile test results showed that the modified asphalt mixtures have a higher resilient modulus than the control asphalt mix. Generally, using Zeolitic tuffs as a modifier of asphalt mixtures enhanced the rutting and fatigue resistance. The results showed that asphalt mixtures fortified with 25% Zeolitic tuffs emerged as the best contenders for rutting resistance. Also, mixtures enriched with 50% Zeolitic tuffs stood out in fatigue resistance performance. Conclusion The best dynamic creep performance was by adding 25% Zeolitic tuffs by the mineral filler mass, while the best resilient modulus was by adding 50% Zeolitic tuffs by the mineral filler mass. Other The overarching goals encompass understanding the dynamic creep behavior of Zeolitic tuff-infused asphalt blends, deciphering its indirect tensile performance, pinpointing the ideal replacement ratio for mineral fillers, and drawing a performance comparison between WMA and conventional Hot Mix Asphalt (HMA) compositions.

Asphaltene Adsorption on Solid Surfaces Investigated Using Quartz Crystal Microbalance with Dissipation under Flow Conditions.

Asphaltenes can cause operational challenges in petroleum production facilities and adversely affect production by adsorption on mineral surfaces and alteration of the oil wettability of reservoirs. Therefore, understanding asphaltene adsorption mechanisms and their effects is crucial to improving the efficiency of oil production and reducing costs. In this study, we focus on understanding the impact of asphaltene concentration and the depositing environment of asphaltene adsorption on solid surfaces using the quartz crystal microbalance with dissipation (QCM-D) technique. The initial and long-term kinetics of adsorption at different concentrations were examined on three different solid surfaces including silicon dioxide to represent quartz mineral, stainless steel, and gold. The frequency-dissipation data showed evidence of monolayer adsorption initially, followed by multilayer formation. At short times, the adsorbed mass increased linearly with time, suggesting that the process was kinetically controlled rather than diffusion-controlled. The results were reproducible and did not depend on convection velocity but did depend on the surface material. At later stages, the monolayer development appeared to follow the random sequential adsorption (RSA) theory. Once multilayer adsorption commenced, the rates agreed well with the two-layer model of Zhu and Gu, 1990. The impact of asphaltene adsorption on the wettability of the surface was examined using contact angle studies, which showed decreasing water wettability with an increase in the adsorbed mass. The contact angle of water after 12 h of adsorption leveled off at around 100° on all three surfaces. Contact angle measurements were also used to evaluate if brine salinity causes the wettability alteration of surfaces with the adsorbed asphaltene. The results indicate that at 3% NaCl solution, the contact angle decreased only slightly by less than 2°.

The Neglected Role of Asphaltene in the Synthesis of Mesophase Pitch.

This study investigates the synthesis of mesophase pitch using low-cost fluid catalytic cracking (FCC) slurry and waste fluid asphaltene (WFA) as raw materials through the co-carbonization method. The resulting mesophase pitch product and its formation mechanism were thoroughly analyzed. Various characterization techniques, including polarizing microscopy, softening point measurement, Fourier-transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA), were employed to characterize and analyze the properties and structure of the mesophase pitch. The experimental results demonstrate that the optimal optical texture of the mesophase product is achieved under specific reaction conditions, including a temperature of 420 °C, pressure of 1 MPa, reaction time of 6 h, and the addition of 2% asphaltene. It was observed that a small amount of asphaltene contributes to the formation of mesophase pitch spheres, facilitating the development of the mesophase. However, excessive content of asphaltene may cover the surface of the mesophase spheres, impeding the contact between them and consequently compromising the optical texture of the mesophase pitch product. Furthermore, the inclusion of asphaltene promotes polymerization reactions in the system, leading to an increase in the average molecular weight of the mesophase pitch. Notably, when the amount of asphaltene added is 2%, the mesophase pitch demonstrates the lowest ID/IG value, indicating superior molecular orientation and larger graphite-like microcrystals. Additionally, researchers found that at this asphaltene concentration, the mesophase pitch exhibits the highest degree of order, as evidenced by the maximum diffraction angle (2θ) and stacking height (Lc) values, and the minimum d002 value. Moreover, the addition of asphaltene enhances the yield and aromaticity of the mesophase pitch and significantly improves the thermal stability of the resulting product.

Bioremediation of Oil-Contaminated Soils of the Zhanazhol Deposit from West Kazakhstan by Pseudomonas mendocina H-3

The culture of Pseudomonas mendocina H-3 was selected as the microorganism for oil destruction, and its effect on oil-contaminated soil from the Zhanazhol deposit in West Kazakhstan was studied. After conducting model laboratory experiments, field experiments were carried out. Six and twelve months after the treatment of the oil-contaminated field with microorganisms, the amount of oil fractions in the soil decreased noticeably, while the content of asphaltenes remained constant. Analyses show that the composition of the oil fraction changes—the concentration of paraffin-naphthenic—polycycloaromatic components decreases, whereas the relative amount of mono- and bicycloaromatic hydrocarbons increases. The results of the efficiency assessment showed that the use of Pseudomonas mendocina H-3 cell suspension in natural conditions leads to a decrease in the content of hydrocarbons in the soil from 55 to 70%. The lower efficiency of bioremediation with cell cultures in field experiments (on average, 61%) compared with laboratory model studies (reduction of oil content to 79%) is apparently associated with climatic conditions.

Remediation of petroleum‐contaminated soil by Fenton oxidation–pyrolysis

AbstractPetroleum‐contaminated soil (PCS) is urgently to be remediated due to its risk to ecological environment and human health. In this study, a Fenton oxidation–pyrolysis strategy was employed to accomplish effective petroleum removal and PCS remediation. The highest total petroleum hydrocarbon removal efficiency could achieve 99.6% after 2 h Fenton oxidation, with H2O2/Fe2+, 6:1, and pH 3, followed by pyrolysis at 370°C. The organic compositions of the soil after Fenton oxidation, the kinetics and process of the pyrolysis, morphologies and structures of the treated soil, as well as energy consumption and cost savings were comprehensively researched and analyzed. Through the Fenton oxidation–pyrolysis treatment, the macromolecules were effectively degraded and the contents of asphaltenes and resins were significantly reduced in the soil. Graphitized carbon was dominatingly existed after the pyrolysis. A 1.5 order reaction model was proposed to reasonably describe the pyrolysis remediation process of PCS. The Fenton oxidation–pyrolysis treatment can reduce energy consumption and cost compared with pyrolysis alone. This work not only offered an alternative approach of PCS remediation, but also provided theoretical guidance for practical soil remediation.

Continuous visbreaking of heavy oil in medium and high-pressure steam environments

Continuous visbreaking of heavy oil in a tubular reactor was studied under pressurized steam environments at 10 MPa (MPS) and 18 MPa (HPS). Within the operating range considered, heavy oil and pressurized steam exhibit a liquid-vapor two-phase structure. During the transition from the MPS environment to the HPS environment, the dissolution of water into the oil phase is promoted, thereby reducing the viscosity of the oil phase. According to the lumped reaction kinetics analysis, the reaction behavior of the lumped component VR2 with a boiling point higher than 700 °C determines the visbreaking efficiency in the early visbreaking stage to a large extent. Dealkylation of VR2 and condensation of the lightest lumped component show sensitive responses to improved diffusion in the oil phase. At 400 °C and a space time of 37 min, visbreaking in HPS environment can achieve a viscosity reduction rate of 90%. Meanwhile, the asphaltene content of the product is lower than the feedstock value.

Role of fiber-reinforced chip seal interlayers in asphalt pavement bonding strength

ABSTRACT This study investigates the influence of seal coat parameters – rubber-modified asphalt content, fiber content, fiber length, and chip content – on the bonding characteristics of asphalt pavement layers. Employing a full factorial experiment and utilizing direct shear and tensile tests, the research identified the optimal material composition for improving interlayer bonding. The results showed that fiber content notably enhanced shear strength, whereas rubber-modified asphalt content significantly influenced tensile strength. The inclusion of fibers in the seal coat notably increased bonding strengths by up to 45.6% and 61.5% in shear and tensile strengths, respectively, demonstrating considerable performance enhancements at room temperature. In addition, the study explored the economic advantages of fiber-reinforced chip seal treatments, revealing substantial improvements in interlayer strength, particularly under diverse temperature conditions. This research contributes valuable insights into optimizing reinforced bituminous interfaces for asphalt pavements, offering a promising avenue for enhancing pavement durability and performance.

Investigating the Impact of Hydrocarbon Solvent on In-Situ Asphaltene Precipitation in Solvent-Assisted Cyclic Steam Technique

Summary Heavy oil recovery techniques often confront a significant challenge in in-situ asphaltene precipitation. This procedure significantly affects the characteristics of reservoirs and impedes optimal oil extraction. The purpose of this research was to examine how hydrocarbon solvents affect asphaltene precipitation occurring naturally in the reservoir as well as the resulting asphaltene content in processed oil. This was conducted using a laboratory-level dynamic model and the solvent-assisted cyclic steam stimulation (CSS) method. Throughout this experiment, which comprised six cycles, the steam-solvent blend’s pressure was consistently maintained close to 680 psi and the temperature was maintained at 500°F at the injection point. The findings revealed crude oil cracking at this temperature and noticeable in-situ asphaltene precipitation during the solvent-assisted CSS process. Notably, asphaltenes demonstrated mobility within porous media, contributing to their production in subsequent CSS cycles. Compared to a steam-only CSS control experiment, a higher asphaltene content in the original oil was observed, indicating that thermodynamic changes during the experiments likely caused asphaltene cracking. To sum up, this research provides an understanding of the effects of heavy oil recovery methods that rely on solvents on the precipitation of in-situ asphaltene and the content of asphaltene in the refined oil.

Pickering stabilization of water-in-crude oil emulsions by paraffin wax crystals: Insights from X-ray scattering

Previous studies suggest asphaltenes are active materials at the oil-water interface, affecting the formation and stability of crude oil emulsions. However, even oils of low asphaltene content generate stable emulsions, indicating the involvement of other oil fractions. Due to the role of paraffin waxes as Pickering stabilizers or gel network formers in emulsions from other applications, this study explores their stabilization capacity in water-in-oil (W/O) emulsions and their interaction with other fractions with interfacial activity. The extraction and physicochemical characterization of paraffin waxes from two Brazilian crude oils allowed us to correlate their properties with the emulsification of both crude and model oils. Removal of asphaltenes enhances emulsion stability. Emulsion preparation with crude oils without waxes and asphaltenes demonstrates the participation of other amphiphilic components in emulsion formation, whereas waxes are necessary for their stabilization. Experiments with emulsions formed by a model oil confirmed the combined action of waxes and an amphiphilic material in the formation and stabilization of the interfacial film. However, the combination of waxes and asphaltenes are ineffective. Small-angle X-ray scattering (SAXS) analysis revealed that waxes only form a lamellar structure when highly purified, suggesting Pickering stabilization rather than the formation of a gel network. In conclusion, polar oil fractions other than asphaltene play a crucial role in emulsion formation, whereas paraffin wax provides Pickering stabilization, even beyond the wax appearance temperature (WAT). This study enhances our understanding of the mechanisms governing waxy Brazilian crude oil emulsions.

Study on the development and performance optimization of gussasphalt containing high percent of fine reclaimed asphalt pavement

Currently, the utilization rate of fine reclaimed asphalt pavement (FRAP) in hot recycled asphalt mixtures is low. Therefore, this study focuses on the development and performance optimization of recycled gussasphalt (RGA) with a FRAP content of 38.5%. The total content of reclaimed asphalt pavement (RAP) is 50%. The impact of various factors on the pavement performance of RGA, including modifier dosage, asphalt content, type of asphalt, rejuvenating agent, mixing time, and RAP preheating temperature was analyzed. The results show that RGA has good workability and fatigue resistance. Its high- and low-temperature performance meets the requirements of the Chinese specification for gussasphalt, but it is still slightly inferior to gussasphalt made from virgin materials. Increasing the preheating temperature of RAP and extending the mixing time of RGA can enhance the performance of RGA. But excessive increases will cause asphalt aging, which negatively affects RGA's low-temperature performance and fluidity. More attention should be given to improving the low-temperature performance of RGA, which can be improved by selecting asphalt with better resistance to aging or by incorporating a rejuvenating agent. RGA offers significant economic benefits, with a cost reduction of approximately 27% compared to GA.

The Effect of Nano-Hydrated Lime on the Durability of Hot Mix Asphalt

Recently, some of Iraq's newly constructed asphalt concrete pavements showed premature failures with significant negative impacts on roadway safety and the economy. Using Nano hydrated lime (NHL) in pavement construction could be one of the possible steps to improve pavement durability. This article discusses how NHL affects the durability of hot mix asphalt. NHL was added in two methods to the asphalt concrete mixture for the wearing course. The first is the dry method, i.e., on the aggregate, whereas the second is the wet addition method, i.e., to the bitumen. The percentages were tried for each additional method; 1, 2, and 3% by weight of aggregate for the dry method and 0.5, 1, and 1.5% by weight of asphalt concrete for the wet method. The optimum asphalt cement contents were evaluated using the Marshall procedure. Asphalt concrete mixes were prepared at their optimum asphalt content and then tested to evaluate their durability properties, including moisture damage and permanent deformation. These properties have been evaluated using indirect tensile strength and uniaxial repeated loading tests. The results show that the NHL has improved the permanent deformation characteristics and resistance to moisture susceptibility.

Workability of low-density polyethylene modified asphalt mixtures: A statistical analysis of particle kinematics

The utilization of recycled plastics in asphalt pavements has gained considerable attention due to its economic, environmental, and engineering benefits. However, incorporating plastics into asphalt mixtures poses challenges to their workability, sometimes leading to a detrimental impact on engineering performance. To address this limitation, this study introduces an innovative analytical approach to examine the impact of Low-Density Polyethylene (LDPE) and its processing techniques on the workability of the asphalt mixture. A particle-size wireless sensor, SmartKli, was utilized to collect the particle kinematic behaviors during compaction. The effect of various mix designs or production methods on the mixture's workability was determined by statistically analyzing the sensing data, including Two One-Sided T-tests and one sample T-test. In this project, seven mixtures with various asphalt content, and LDPE dosage were studied. The recycled plastic-modified asphalt (RPMA) was produced using two dry processing methods and one wet processing method. The results validate the significance of asphalt content on the mixture's workability. A linear correlation was observed between the active asphalt content and the mixture's workability, even in the presence of plastics. Under the identical mix design, the wet processing method proved more effective than the dry methods in integrating LDPE, as evidenced by the workability of the RPMAs. For asphalt mixtures with plastics, ensuring sufficient binder content is essential for maintaining workability, particularly in RPMAs processed via dry methods.