Special Issue "Asphalt Materials"

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Materials".

Deadline for manuscript submissions: 31 December 2019.

Special Issue Editors

Prof. Dr. Cesare Oliviero Rossi
E-Mail
Guest Editor
Department of Chemistry and Chemical technologies, University of Calabria, Via P. Bucci, Cubo 14/D – 87036 Arcavacata, Italy
Interests: Bitumen: Physical Chemistry Characterization and Modification, Surfactant self-assembly, Biodegradable surface-active molecules; Shear-induced formation of multi-lamellar vesicles, Emulsions
Prof. Dr. Bagdat Teltayev
E-Mail
Guest Editor
Kazakhstan Highway Research Institute, Nurpeisova Str., 2A, Almaty 050061 Kazakhstan

Special Issue Information

Dear Colleagues,

In last few years, the standards imposed by companies operating in road construction have become higher and higher; consequently, the need for increasingly high performance and wear-resistant pavements push research to explore new materials.

In every part of the world, new roads or pavement maintenance works are carried out.

New asphalt materials have to provide solutions for today's requirements, such as durability, reduction of emissions, high performances, and energy consumption.

Life span and sustainability are very important for the paving industry.

For the purpose of improving the qualitative properties of bitumen and asphalts, additives are applied, e.g., to increase elasticity, improving the heat stability, improving adhesion to aggregate, to decrease viscosity, increasing resistance to aging, to prevent binder drainage from the aggregate surface, etc.

The aim of this Special Issue is to attract world-leading researchers in the area of bitumen and asphalt materials in an effort to highlight the latest exciting developments, discuss the underlying properties of various investigated materials, and promote concrete applications.

This Special Issue is going to provide an information source on material characterization, theoretical aspects, and experimental techniques for asphalt and modified asphalt binder properties; modeling of pavement materials; testing and investigation of binders; and new techniques for material modification.

We would like to extend our sincere gratitude and appreciation to all authors.

Prof. Dr. Cesare Oliviero Rossi
Prof. Dr. Bagdat Teltayev
Guest Editors

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Keywords

  • Asphalt
  • Bitumen
  • Advanced Binder
  • Additives
  • Road Materials
  • Materials Modelling
  • Advanced Techniques
  • Road data collection

Published Papers (30 papers)

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Open AccessArticle
Silane Modification of Crumb Rubber on the Rheological Properties of Rubberized Asphalt
Appl. Sci. 2019, 9(22), 4831; https://doi.org/10.3390/app9224831 - 12 Nov 2019
Abstract
Because there is a lack of studies on rubberized asphalt based on silane coupling agent modification, KH-550 modified crumb rubber and rubberized asphalts incorporating normal rubber and modified rubber were prepared, respectively. The rheological properties of asphalt samples were evaluated by a dynamic [...] Read more.
Because there is a lack of studies on rubberized asphalt based on silane coupling agent modification, KH-550 modified crumb rubber and rubberized asphalts incorporating normal rubber and modified rubber were prepared, respectively. The rheological properties of asphalt samples were evaluated by a dynamic shearing rheometer and a bending beam rheometer; then, mechanisms of KH-550 on rubber surface and functional group changes were analyzed by a Brunauer–Emmett–Teller specific surface area measurement and a Fourier transform infrared spectroscopy. The results imply that: (i) rubber surface area rises and chemical reactions accrue between rubber and asphalt; (ii) modified rubber achieves a more stable state within asphalt, which helps to enhance the mechanical properties of asphalt; (iii) modified rubber helps asphalt to dissipate stress so as to resist the formation of cracks and deformation under low temperature conditions. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Effect of Characteristics of Different Types of Bauxite Clinker on Adhesion
Appl. Sci. 2019, 9(22), 4746; https://doi.org/10.3390/app9224746 - 07 Nov 2019
Abstract
Based on the fact that bauxite clinker has minor thermal conductivity and better skid resistance and wear-resisting property, it can be used in HFST (high friction surface treatment) or the abrasion layer of asphalt mixture to replace or partly replace the existing aggregate. [...] Read more.
Based on the fact that bauxite clinker has minor thermal conductivity and better skid resistance and wear-resisting property, it can be used in HFST (high friction surface treatment) or the abrasion layer of asphalt mixture to replace or partly replace the existing aggregate. Bauxite clinker is classified into mainly six types according to different chemical composition contents. The selection of bauxite clinker as aggregate is not only for the economic value, but also for improving the adhesion between aggregate and asphalt, which has a certain blindness This study evaluated the characteristics of different types of bauxite clinker. The adhesion of different types of bauxite clinker with asphalt was evaluated by means of agitating hydrostatic adsorption method and surface free energy theory. The effect of characteristic parameters of bauxite clinker on adhesion was evaluated by grey correlation entropy analysis. The results show that Type B and D bauxite clinker aggregates have the best adhesion to asphalt. The outcome of grey entropy correlation analysis shows that the parameters which characterize the structural indexes of bauxite clinker, such as porosity, water absorption and apparent density, have the greatest effect on the adhesion. The results of study can provide some reference for the selection of bauxite clinker, which is used in different types of highway construction, and a theoretical reference for the applicability research of bauxite clinker in asphalt mixture and the improvement of skid resistance and durability of pavement. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Improvement Methods for Reduction of the High Stress of Ultra-High Asphalt Concrete Core Dams
Appl. Sci. 2019, 9(21), 4618; https://doi.org/10.3390/app9214618 - 30 Oct 2019
Abstract
With the rapid development of asphalt concrete core rockfill dams (ACCRDs), the construction of ultra-high asphalt concrete core rockfill dams (UACCRDs) has been improved significantly. However, the security problems of asphalt concrete core (ACC) become very prominent with the increase of dam height. [...] Read more.
With the rapid development of asphalt concrete core rockfill dams (ACCRDs), the construction of ultra-high asphalt concrete core rockfill dams (UACCRDs) has been improved significantly. However, the security problems of asphalt concrete core (ACC) become very prominent with the increase of dam height. The shear failure control standard and tensile failure control standard of ACC are suggested. The mechanisms of ACC that generate high shear stress and high tensile stress are investigated. Based on the definition of stress level and the transmission mechanism of arch structures, the improvement methods that reduce the high shear stress and high tensile stress of ultra-high asphalt concrete core (UACC) are proposed and investigated. The results show that the stress level of ACC can be reduced significantly by the increase of the strength parameters of ACC (failure ratio, cohesion, and internal friction angle). The following value ranges of the failure ratio, cohesion, and internal friction angle of ACC for the suitable construction of UACCRDs are recommended: Rf ≥ 0.75, C ≥ 0.30 MPa, and φ ≥ 28.5° (h = 150 m), with the growth gradient adjusted by 5%, 15%, and 5%/25 m. The tensile stress and tensile stress area can be reduced obviously by the new type of dams (curved asphalt concrete core rockfill dams (CACCRDs)). The value ranges of the curvature of CACC (k ≥ 1.0 × 10−3) for the suitable construction of UACCRDs are recommended. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Viscoelastic Properties of Asphalt Mixtures with Different Modifiers at Different Temperatures Based on Static Creep Tests
Appl. Sci. 2019, 9(20), 4246; https://doi.org/10.3390/app9204246 - 11 Oct 2019
Abstract
To obtain the viscoelastic parameters of asphalt mixtures and analyze the effect of temperatures and modifiers on viscoelastic properties of asphalt mixtures, the creep compliances of the neat asphalt mixture (AM), compound diatomite and basalt fibers reinforced asphalt mixture (DBFAM), and styrene-butadiene-styrene modified [...] Read more.
To obtain the viscoelastic parameters of asphalt mixtures and analyze the effect of temperatures and modifiers on viscoelastic properties of asphalt mixtures, the creep compliances of the neat asphalt mixture (AM), compound diatomite and basalt fibers reinforced asphalt mixture (DBFAM), and styrene-butadiene-styrene modified asphalt mixture (SBSAM) were tested and calculated by the static creep tests. And the creep compliances of the three asphalt mixtures at −20 °C, −10 °C, and 0 °C are deducted by the time–temperature equivalence principle (TTEP) and Arrhenius equation. Further, the relaxation modulus of the three asphalt mixtures from −20 °C to 50 °C at 10 °C increments are calculated by the convolution integral and Simpson method. Subsequently, the Burgers model, the generalized Kelvin model, and the generalized Maxwell model are applied to analyze the viscoelastic properties of the three asphalt mixtures at different temperatures. The results show that the generalized Kelvin model and the generalized Maxwell model are superior to the Burgers model in describing the variation of viscoelastic properties of asphalt mixtures with loading time. At low temperatures, asphalt mixtures have excellent properties in resisting permanent deformation and releasing internal stress. Besides, the addition of SBS modifier and compound diatomite and basalt fibers modifier can significantly raise the viscosity η1 and the elastic modulus E1 of the asphalt mixture, respectively. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Characterization of Air Voids Distribution in the Open-Graded Asphalt Mixture Based on 2D Image Analysis
Appl. Sci. 2019, 9(19), 4126; https://doi.org/10.3390/app9194126 - 02 Oct 2019
Abstract
The air voids distribution has a significant effect on the pavement performance related distresses such as rutting, cracking, moisture damage and permeability. However, most studies only quantified the air voids by average content, ignoring the heterogeneity inside the materials. This study focuses on [...] Read more.
The air voids distribution has a significant effect on the pavement performance related distresses such as rutting, cracking, moisture damage and permeability. However, most studies only quantified the air voids by average content, ignoring the heterogeneity inside the materials. This study focuses on the heterogeneity of air voids distribution inside the open-grade asphalt mixture based on 2D image analysis. Equivalent aperture is proposed to measure the area of each air void. Results showed that along both vertical and horizontal sections inside the open-grade asphalt mixture, the number of voids with 0~2 mm equivalent aperture would have a great impact on the total number of voids, while large amounts of small voids would not significantly affect the total voids number. Additionally, voids with 0~4 mm equivalent aperture account for the largest proportion, and when the equivalent aperture is beyond 4 mm, the number of voids would decrease as the equivalent aperture increases, regardless of the void areas. Furthermore, in both vertical and horizontal sections, as the equivalent aperture increases, the speed to accumulate voids area would firstly increase and then decrease. As the equivalent aperture increases, the contribution to the total voids area would increase accordingly, and it would approach the peak when the equivalent aperture reaches about 8 mm. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Effects of Cement–Mineral Filler on Asphalt Mixture Performance under Different Aging Procedures
Appl. Sci. 2019, 9(18), 3785; https://doi.org/10.3390/app9183785 - 10 Sep 2019
Abstract
Cement-containing mineral powder can effectively improve the moisture stability of an asphalt mixture; therefore, this study systematically summarizes the research status of cement–mineral fillers on the performance of an asphalt mixture and determines the limitations of related studies. In this study, long-term performance [...] Read more.
Cement-containing mineral powder can effectively improve the moisture stability of an asphalt mixture; therefore, this study systematically summarizes the research status of cement–mineral fillers on the performance of an asphalt mixture and determines the limitations of related studies. In this study, long-term performance tests of styrene-butadiene-styrene- (SBS)-modified asphalt mixtures are designed and evaluated with different blending ratios of the cement–mineral powder under three aging conditions. Moreover, the effect of the cement–mineral composite filler on long-term performance of the asphalt mixture using different blending ratios is determined. Cement improves the high-temperature performance and water stability of asphalt mixtures, but only for certain aging conditions. Considering the regulations for the road performance of asphalt mixtures for three aging conditions, as well as long-term performance considerations, the results indicated that the mass ratio of Portland cement to mineral powder must not exceed 2:2. Low-temperature bending and splitting tensile tests confirmed that an excessive amount of cement filler will embrittle the modified asphalt mixture during long-term aging, thereby deteriorating the tensile properties. The mechanism by which the filler influences the performance of the asphalt mixture should be further studied from the perspective of microscopic and molecular dynamics. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Durability Evaluation Study for Crumb Rubber–Asphalt Pavement
Appl. Sci. 2019, 9(16), 3434; https://doi.org/10.3390/app9163434 - 20 Aug 2019
Abstract
In this study, the failure mechanism of crumb rubber–asphalt pavement was analyzed under the combined effects of low temperature, water, and traffic load. The investigation was carried out based on the mechanical and deformational properties of crumb rubber–asphalt mixture and the typical environmental [...] Read more.
In this study, the failure mechanism of crumb rubber–asphalt pavement was analyzed under the combined effects of low temperature, water, and traffic load. The investigation was carried out based on the mechanical and deformational properties of crumb rubber–asphalt mixture and the typical environmental and load conditions such pavement is typically exposed to. A method was proposed for objective evaluation of the interfacial adhesion between rubber crumbs and asphalt through consideration of the effects of the characteristics of the materials and the working environment. The main evaluation method used herein included the indirect tensile strength test under freeze–thaw–boiling cycle, and the Cántabro abrasion test under water-immersion was adopted as an auxiliary method. The evaluation system has the advantages of simple implementation, realistic simulation of the actual working state of the mixture, and reliable results. Moreover, it is a durability evaluation method that can be specifically applied to asphalt mixtures with some special aggregates or stone mastic asphalt (SMA) mixtures. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessFeature PaperArticle
Microtexture Performance of EAF Slags Used as Aggregate in Asphalt Mixes: A Comparative Study with Surface Properties of Natural Stones
Appl. Sci. 2019, 9(15), 3197; https://doi.org/10.3390/app9153197 - 06 Aug 2019
Cited by 1
Abstract
Steelmaking industries produce a large amount of solid wastes that need to be adequately managed in order to ensure environmental sustainability and reduce the impact of their disposal on earth pollution. Electric arc furnace (EAF) slags are those wastes deriving from secondary steelmaking [...] Read more.
Steelmaking industries produce a large amount of solid wastes that need to be adequately managed in order to ensure environmental sustainability and reduce the impact of their disposal on earth pollution. Electric arc furnace (EAF) slags are those wastes deriving from secondary steelmaking production; these slags can be re-used and recycled in many industrial applications such as the production of asphalt mixes. In this paper authors investigate the surface performance of EAF slags used as second-hand aggregate in asphalt mixes. In particular, slags behavior under polishing is compared to other types of aggregate commonly used for asphalt concrete such as limestone, basalt, and kinginzite. Several devices (skid tester, laser profilometer, polishing machine) were used to collect experimental data; the analysis of microtexture was carried out by comparing aggregate surface performance before and after polishing. Results show that EAF slags are positively comparable to basalt as concerns the polishing behavior; good correlations between skid resistance and some microtexture indicators are also carried out. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Effect of Thermo-Oxidative Ageing on Nano-Morphology of Bitumen
Appl. Sci. 2019, 9(15), 3027; https://doi.org/10.3390/app9153027 - 26 Jul 2019
Abstract
In recent years, the research on bitumen has reached the nanometer level, but there are still some problems in the study of the relationship between the atomic force microscope (AFM) nano-morphology and ageing of bitumen. The purpose of this paper is to find [...] Read more.
In recent years, the research on bitumen has reached the nanometer level, but there are still some problems in the study of the relationship between the atomic force microscope (AFM) nano-morphology and ageing of bitumen. The purpose of this paper is to find out the effect of thermal oxygen ageing on the nano-morphology of bitumen. Atomic force microscope (AFM) test sample of bitumen was prepared in this paper. Area ratio of bee-like structure, roughness, and maximum amplitude were selected as the nano-morphological parameters of the bitumen. The calculation method of nano-parameters was also proposed. Bitumen with different ageing degrees was prepared by thin film oven test (TFOT). Nano-morphological parameters of bitumen with different ageing degrees were obtained by AFM and analyzed with NanoScope Analysis, and the relationships between nano-morphological parameters and bitumen technical indexes after ageing, such as penetration, ductility, softening point, and viscosity were analyzed. The test results show that the wave crests and wave troughs of the bee-like structure on the surface of the bitumen alternate, while the other areas are relatively flat. The bee-like structure continues to develop as the ageing time prolongs, and the number of bee-like structures decreases, but the volume and the undulation degree increase. With the ageing time prolonging, the nano-parameters of bitumen, such as the area ratio of bee-like structure, roughness, and maximum amplitude, show a trend of increasing gradually, but the increasing rates become smaller and smaller. During the ageing process of bitumen, with the increase of nano-morphological parameters (area ratio of bee-like structure, roughness, and maximum amplitude), penetration at 25 °C and ductility at 15 °C of the bitumen decrease, and softening point and viscosity at 60 °C increase. AFM testing technology and image analysis method in this paper can be used for a reference in the nano-scale study of bitumen. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Performance and Reinforcement Mechanism of Modified Asphalt Binders with Nano-Particles, Whiskers, and Fibers
Appl. Sci. 2019, 9(15), 2995; https://doi.org/10.3390/app9152995 - 26 Jul 2019
Abstract
The asphalt binders could be modified to improve road perfo rmances by using various methods, and the reinforcement mechanisms are obviously different and quietly affect the road performances. According to the composite reinforcement theory, nano-CaCO3 particles, CaCO3 whiskers, and aramid fibers [...] Read more.
The asphalt binders could be modified to improve road perfo rmances by using various methods, and the reinforcement mechanisms are obviously different and quietly affect the road performances. According to the composite reinforcement theory, nano-CaCO3 particles, CaCO3 whiskers, and aramid fibers were used as reinforcements to prepare modified asphalt binders, and the conventional technical performances and dynamic shear rheometer (DSR) rheological properties were measured and investigated. In addition, scanning electron microscopy (SEM) was applied to observe the interfaces between reinforcements and asphalt matrixes and the different reinforcement mechanisms were analyzed. The test results showed that the use of nano-CaCO3 particles, CaCO3 whiskers, and aramid fibers can improve the high-temperature stability of modified asphalt binders by different reinforcement mechanisms. The nano-CaCO3 particles were still effective under high-temperature conditions and could last for a long time through the principle of dispersion enhancement. The CaCO3 whiskers segregate easily and cannot be well dispersed in asphalt binders. The aramid fibers played an important role of stress transmission and fiber reinforcement in asphalt binders, and 2 mm-aramid fibers hold the best reinforcement effects. The conclusions can provide a reference for the selection and application of modifiers in the preparation of modified asphalt in laboratory and engineering projects. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Blistering Mechanism Analysis of Hydraulic Asphalt Concrete Facing
Appl. Sci. 2019, 9(14), 2903; https://doi.org/10.3390/app9142903 - 19 Jul 2019
Abstract
Two years after the Zhanghewan Pumped-Storage Power Station was put into operation, more than 500 blisters appeared in the asphalt concrete facing of the upper reservoir, and nearly half of them ruptured at the surface. The blistering mechanism of the asphalt concrete facing [...] Read more.
Two years after the Zhanghewan Pumped-Storage Power Station was put into operation, more than 500 blisters appeared in the asphalt concrete facing of the upper reservoir, and nearly half of them ruptured at the surface. The blistering mechanism of the asphalt concrete facing was studied in this paper. Through on-site inspection and coring inspection, it was found that the blistering was caused by the vapor pressure formed by the water enclosed in the middle of the impervious layer during high temperatures. Numerical analysis showed that the temperature 5 cm below the surface could reach 50–60 °C. Through numerical analysis and model tests, the internal water at this temperature may form a vapor pressure of 20 kPa. Finally, the blister size of the asphalt concrete facing at this temperature and pressure was studied with a model test. The possible sources of moisture inside the impervious layer were also analyzed through a core test, which found that moisture was most likely to be introduced by water spraying during rolling. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Investigation of Crack Propagation and Healing of Asphalt Concrete Using Digital Image Correlation
Appl. Sci. 2019, 9(12), 2459; https://doi.org/10.3390/app9122459 - 16 Jun 2019
Cited by 2
Abstract
The fatigue performance and healing ability of asphalt pavements are important for mixture design, rehabilitation, and maintenance of the roads. By analyzing these parameters in an asphalt mixture, it is possible to predict the crack formation and propagation in asphalt pavements and healing [...] Read more.
The fatigue performance and healing ability of asphalt pavements are important for mixture design, rehabilitation, and maintenance of the roads. By analyzing these parameters in an asphalt mixture, it is possible to predict the crack formation and propagation in asphalt pavements and healing of these cracks during the rest periods. The healing effect in asphalt mixtures has been observed and verified by many researchers and different methods exist to evaluate this phenomenon. However, current methods are still inadequate to fully observe and quantify the healing phenomenon in asphalt mixtures. In this study, a digital image correlation (DIC) method is used to calculate the strain map on the surface of cylindrical asphalt specimens during the indirect tensile fatigue test. This strain map is used to detect the location of crack initiations and development of the microcracks during the experiments. Next, the specimens are unloaded and the temperature of the climate chamber is increased to 60 °C for 18 h to investigate the healing phenomenon on the surface of the specimens. It is observed that the strain reduces near the microcrack areas especially at the tip of the microcracks. Furthermore, using DIC it is possible to observe the healing rate and the minimum time required to heal the microcracks on the surface of the specimens. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Experimental Study on Hydraulic Fracturing of High Asphalt Concrete Core Rock-Fill Dam
Appl. Sci. 2019, 9(11), 2285; https://doi.org/10.3390/app9112285 - 03 Jun 2019
Cited by 2
Abstract
In this paper, we experiment on the hydraulic fracturing of asphalt concrete with a voids content higher than 3%, which has arisen from the possible local shear dilatancy of Quxue asphalt’s core wall of concrete core dam, the highest one of the sort [...] Read more.
In this paper, we experiment on the hydraulic fracturing of asphalt concrete with a voids content higher than 3%, which has arisen from the possible local shear dilatancy of Quxue asphalt’s core wall of concrete core dam, the highest one of the sort constructed in the world. The model test has shown that under the sole water pressure 0.13 MPa—relevant to the pressure where the dilatancy could appear at core wall of Quxue dam—the asphalt concrete with a voids content of 3.5% underwent hydraulic fracturing. Furthermore, the asphalt concrete with a voids content of 3.0% was tested for nearly 500 h and no sign of hydraulic fracturing was found, which again confirmed the threshold requirement for a 3% voids content to the impervious asphalt concrete to the hydraulic fracture concern. According to the analysis of the test result, the theory of fracture mechanics could be applied to the hydraulic fracture of asphalt concrete with a voids content between 3.4~4.0%, which behaved during hydraulic fracturing like a quasi-brittle material, similar to concrete. Because the hydraulic fracturing could occur in the shear dilatant asphalt concrete, a proper mix proportion of asphalt concrete to a project with adverse stress state should be carefully designed to rule out the possibility of shear dilatancy. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Influence of Ultraviolet Aging on Adhesion Performance of Warm Mix Asphalt Based on the Surface Free Energy Theory
Appl. Sci. 2019, 9(10), 2046; https://doi.org/10.3390/app9102046 - 17 May 2019
Cited by 1
Abstract
To explore the effect of ultraviolet (UV) aging on the adhesion properties of warm mix asphalt (WMA), WMA binders were prepared by adding Evotherm M1 and Sasobit into base asphalt. The base asphalt and two WMA binders were aged using a self-made UV [...] Read more.
To explore the effect of ultraviolet (UV) aging on the adhesion properties of warm mix asphalt (WMA), WMA binders were prepared by adding Evotherm M1 and Sasobit into base asphalt. The base asphalt and two WMA binders were aged using a self-made UV aging box after a rolling thin-film oven test (RTFOT). As a comparison, pressure aging vessel (PAV) tests were performed for asphalt binders after RTFOT. The contact angles between the WMA binder and distilled water, glycerol, and formamide, before and after UV aging, were measured using the sessile drop method. On the basis of the surface free energy (SFE) theory, the SFE and its components, cohesion work, adhesion work, peeling work, and compatibility rate, before and after the UV aging of WMA, were obtained. The results show that the contact angle between WMA and water gradually increases with the degree of UV aging, which indicates that the aging increases the hydrophobicity of asphalt. After the RTFOT aging, UV aging at different times, and PAV aging, the SFE and its component, as well as cohesion work for all asphalt binders were reduced. The attenuation was severe after UV aging, followed by PAV aging and RTFOT aging. With the extension of UV aging time, the adhesion work, hot mix asphalt, and limestone aggregate compatibility rate gradually reduced, the peeling work increased, and the overall adhesion performance became poor. Under the aging effect of RTFOT and PAV, the Evotherm M1 WMA had the strongest anti-peeling ability, better compatibility, and the best adhesion. When the UV aging time of Sasobit WMA reached 100 h, the adhesion performance increased. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
A Study on the Design Method for the Material Composition of Small Particle-Size Asphalt Mixture for Controlling Cracks in Asphalt Pavement
Appl. Sci. 2019, 9(10), 1988; https://doi.org/10.3390/app9101988 - 15 May 2019
Cited by 1
Abstract
Generally, various kinds of cracks are the main type of distresses during the service period of asphalt pavements. To save maintenance costs and improve the crack resistance of asphalt pavements effectively, this paper presents a unique design method for the material composition of [...] Read more.
Generally, various kinds of cracks are the main type of distresses during the service period of asphalt pavements. To save maintenance costs and improve the crack resistance of asphalt pavements effectively, this paper presents a unique design method for the material composition of small particle-size (SPS) asphalt mixture for controlling cracks in asphalt pavement. First, Stone Mastic Asphalt (SMA)-II was designed as a basic gradation according to the A.N. Talbot curve and SMA-II-1, SMA-II-2 and SMA-II-3 were designed according to the Superpave mix design method, the Bailey method and the Particle interference theory, respectively. Second, based on Marshall test results, the optimal fiber content and optimal asphalt content of three gradations were determined. Then, the influence of the passing rate of 1.18-mm sieve and 0.075-mm sieve on the air voids of SMA-II and the influence of the filler-asphalt ratio on the performance of SMA-II were investigated, and an appropriate range of filler-asphalt ratio was obtained. Finally, a high-temperature performance test, a water stability test, and a skid resistance test demonstrate that the overall performance of SMA-II can satisfy the specifications. A low-temperature bend test and analysis of bending strain energy density show that SMA-II with a crumb rubber modifier and a polymer fiber has better crack resistance performance than SMA-I (SBS-modified mixture). Life-cycle cost analysis shows the economic advantage of SPS asphalt thin overlays over traditional AC-13 thin overlays. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Timely and Durable Polymer Modified Patching Materials for Pothole Repairs in Low Temperature and Wet Conditions
Appl. Sci. 2019, 9(9), 1949; https://doi.org/10.3390/app9091949 - 12 May 2019
Abstract
Aiming to solve the contradiction between the workability and performance of pothole patching using cold mixtures, this paper proposed new patching materials based on the microcapsule technique and polymer reinforcement, namely cold mixtures with polymer modified asphalt and dense graded (DG) of aggregates [...] Read more.
Aiming to solve the contradiction between the workability and performance of pothole patching using cold mixtures, this paper proposed new patching materials based on the microcapsule technique and polymer reinforcement, namely cold mixtures with polymer modified asphalt and dense graded (DG) of aggregates (PADG) mixtures. Laboratory tests were conducted to compare the PADG mixtures with commonly used DG mixtures and open graded (OG) mixtures concerning workability, storability, cohesion, stability, and durability of each mixture. The results found that the PADG mixtures were satisfactory in their workability and storability and were as satisfactory as the OG mixtures. Meanwhile, stability and durability of the PADG mixtures was better than the DG mixtures and OG mixtures, i.e., the PADG mixtures showed stability in the conditions of the timeliness, low temperature, and immersion, as well as the freeze-thaw resistance and wear resistance in wet conditions. Therefore, it can be concluded that PADG mixtures are applicable in timely and durable pothole repairs in low temperatures and wet conditions. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Effects of Vehicular Speed on the Assessment of Pavement Road Roughness
Appl. Sci. 2019, 9(9), 1783; https://doi.org/10.3390/app9091783 - 29 Apr 2019
Cited by 2
Abstract
Good ride quality is a fundamental requirement for all road networks in modern countries. For this purpose, it is essential to monitor and evaluate the effect of irregularities on road pavement surfaces. In the last few decades, many roughness indices have been proposed, [...] Read more.
Good ride quality is a fundamental requirement for all road networks in modern countries. For this purpose, it is essential to monitor and evaluate the effect of irregularities on road pavement surfaces. In the last few decades, many roughness indices have been proposed, with the aim to represent shortly the pavement surface characteristics and the relative performances, using a single number and a correspondent scale of values. In this work, a comparison between three different evaluation methods (International Roughness Index, ISO 8608 road profile classification and frequency-weighted vertical acceleration awz according to ISO 2631) was carried out, applying these methods to some real road profiles. The similarities and differences between the obtained results are described, evaluating the effect of the road characteristic speed on the roughness thresholds. In fact, the specific aim of the analyses is to underline the need to use different thresholds depending on the speed at which the vehicular traffic can travel on the road sections. In this way, it will be possible to identify appropriate thresholds for the various types of roads, having for each of them a specific range of design or operating speed. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Labeling Strategy for Evaluating the Performance of Thin Asphalt Wearing Courses
Appl. Sci. 2019, 9(8), 1694; https://doi.org/10.3390/app9081694 - 24 Apr 2019
Abstract
Traditional design procedures of asphalt mixtures are based on volumetric parameters and the compliance with the mechanical performance, while functional properties receive less attention. Additionally, even though the potential of sustainable technologies is proven, this is not sufficiently reflected in the technical specifications [...] Read more.
Traditional design procedures of asphalt mixtures are based on volumetric parameters and the compliance with the mechanical performance, while functional properties receive less attention. Additionally, even though the potential of sustainable technologies is proven, this is not sufficiently reflected in the technical specifications and their use is not widely spread. In order to face these challenges, the development of a useful tool that allows infrastructure managers an easy evaluation of the mechanical, functional, and environmental performance and the pursuit of balance between properties will encourage the optimization of road surfaces. The aim of this research is to develop a multi-labeling scheme for asphalt mixtures for thin wearing courses according to their mechanical, functional, and environmental attributes. In particular, the study focuses on the Spanish case, because all the collected data belong to the Spanish road network; however, the approached methodology is flexible enough to be adjusted to the requirements of individual countries. The findings in this research show promise because the developed labeling scheme allows not only the assignation of performance labels to any asphalt mixture based on its properties, but also the comparison of features between different asphalt mixtures. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Assessment of Thermal Stresses in Asphalt Mixtures at Low Temperatures Using the Tensile Creep Test and the Bending Beam Creep Test
Appl. Sci. 2019, 9(5), 846; https://doi.org/10.3390/app9050846 - 27 Feb 2019
Abstract
Thermal stresses are leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when the temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of [...] Read more.
Thermal stresses are leading factors that influence low-temperature cracking behavior of asphalt pavements. During winter, when the temperature drops to significantly low values, tensile thermal stresses develop as a result of pavement contraction. Creep test methods can be suitable for the assessment of low-temperature properties of asphalt mixtures. To evaluate the influence of creep test methods on the obtained low-temperature properties of asphalt mixtures, three point bending and uniaxial tensile creep tests were applied and the master curves of stiffness modulus were analyzed. On the basis of creep test results, rheological parameters describing elastic and viscous properties of the asphalt mixtures were determined. Thermal stresses were calculated and compared to the tensile strength of the material to obtain the failure temperature of the analyzed asphalt mixtures. It was noted that lower strain values of creep curves were obtained for the Tensile Creep Test (TCT) than for the Bending Beam Creep Test (BBCT), especially at lower temperatures. Results of thermal stress calculations indicated that higher reliability was obtained for the viscoelastic Monismith method based on the TCT results than for the simple quasi-elastic solution of Hills and Brien. The highest agreement with the TSRST results was also obtained for the Monismith method based on the TCT results. No clear relationships were noted between the predicted failure temperature and different methods of thermal stress calculations. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Evaluating the Role of Aggregate Gradation on Cracking Performance of Asphalt Concrete for Thin Overlays
Appl. Sci. 2019, 9(4), 628; https://doi.org/10.3390/app9040628 - 13 Feb 2019
Cited by 3
Abstract
Thin asphalt concrete overlays are a maintenance technique that mainly restore the functional properties of pavements. One of the main issues in thin overlays is reflective cracking that can cause early deterioration and reduce their service life. For this reason, the purpose of [...] Read more.
Thin asphalt concrete overlays are a maintenance technique that mainly restore the functional properties of pavements. One of the main issues in thin overlays is reflective cracking that can cause early deterioration and reduce their service life. For this reason, the purpose of this investigation is to evaluate the effect of material selection on cracking performance of asphalt concrete mixtures for thin overlays. In particular, this paper evaluates the role of aggregate skeleton gradation. The study of the effect of aggregate gradation was divided into two stages: (1) fine fraction content and (2) maximum nominal aggregate size. Based on this, up to seven asphalt mixture gradations were designed and evaluated through the Fénix test at different test temperatures. The results showed a significant correlation between the fine fraction content, and maximum nominal aggregate size, and the cracking performance of the asphalt concrete mixtures. Mixtures manufactured with a low content of fine aggregates, as well as small nominal maximum size, experienced a further improvement of their toughness. These results reflected the importance of considering not only the effect of asphalt binder and environmental conditions but also aggregate gradation in the design of asphalt concrete mixtures in order to achieve a desirable cracking performance. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessFeature PaperArticle
Effect of Freeze-Thaw Cycles on Mechanical Characteristics of Bitumens and Stone Mastic Asphalts
Appl. Sci. 2019, 9(3), 458; https://doi.org/10.3390/app9030458 - 29 Jan 2019
Cited by 4
Abstract
The present article investigates in laboratory conditions the effect of cyclic freezing and thawing (CFT) on characteristics of the neat bitumen and bitumens modified with different polymers, as well as stone mastic asphalt concretes prepared with the use of the neat and the [...] Read more.
The present article investigates in laboratory conditions the effect of cyclic freezing and thawing (CFT) on characteristics of the neat bitumen and bitumens modified with different polymers, as well as stone mastic asphalt concretes prepared with the use of the neat and the modified bitumens. Maximal and minimal temperature in cycles of freezing and thawing (FT) is accepted equal to +20 °C and −18 ± 2 °C respectively. Characteristics of low temperature resistance of bitumens (stiffness S and m-value) have been determined on bending beam rheometer at the temperatures of −24 °C, −30 °C, and −36 °C. Strength at direct tension of the stone mastic asphalt concretes has been evaluated in the device TRAVIS (Infratest Ltd., Brackenheim, Germany) at the temperatures of 0 °C, −10 °C, −20 °C, and −30 °C. Resistance of stone mastic asphalt concretes to rutting has been determined on a Hamburg wheel tracking machine. The characteristics of the bitumens have been determined in the initial condition and after 25 and 50 cycles of FT, and the characteristics of stone mastic asphalt concretes, in the initial condition and after 50 cycles of FT. The results obtained experimentally have shown that CFT impacts essentially on the investigated characteristics of bitumens and stone mastic asphalt concretes. Modification with polymers improves the mechanical characteristics of the bitumens and decreases the effect of CFT. It is also found out that when selecting a bitumen for specific climatic conditions it is necessary to take into account both the number of cycles of FT and the characteristic low temperature. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Dynamic Responses of Asphalt Concrete Waterproofing Layer in Ballastless Track
Appl. Sci. 2019, 9(3), 375; https://doi.org/10.3390/app9030375 - 22 Jan 2019
Cited by 2
Abstract
The application of asphalt concrete waterproofing layer (ACWL) for the subgrade has been a trend in Chinese high-speed railway. The purpose of this research is to discuss the dynamic characteristics of full cross-section ACWL in the ballastless track structure under the train loads. [...] Read more.
The application of asphalt concrete waterproofing layer (ACWL) for the subgrade has been a trend in Chinese high-speed railway. The purpose of this research is to discuss the dynamic characteristics of full cross-section ACWL in the ballastless track structure under the train loads. The laboratory tests were conducted to evaluate the performance of the asphalt mixtures for the ACWL and a test section of ACWL was constructed on the high-speed railway in north China. The linear viscoelastic behavior of the asphalt concrete obtained from the test section was characterized by the generalized Maxwell model according to the results of dynamic modulus test. Then a 3D finite element model for the interaction system of vehicle and ballastless track structure was presented and validated by field measured data. The results indicated that the tensile strain at the bottom of the ACWL was at a relatively low level and the vertical dynamic responses of each structural layer are obviously reduced due to the application of ACWL. Therefore, the full cross-section ACWL helps to reduce the vibration of the track structure and maintain the long-term stability of the subgrade. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Investigation on Microstructural Damage Properties of Asphalt Mixture Using Linear and Damage-Coupled Viscoelastic Model
Appl. Sci. 2019, 9(2), 303; https://doi.org/10.3390/app9020303 - 16 Jan 2019
Abstract
This paper presents an image-based micromechanical modeling approach for simulating the damage-couple viscoelastic response of asphalt mixture. Details of the numerical damage-couple viscoelastic constitutive formulation implemented in a finite element code are presented and illustrated by using the ABAQUS user material subroutine (UMAT). [...] Read more.
This paper presents an image-based micromechanical modeling approach for simulating the damage-couple viscoelastic response of asphalt mixture. Details of the numerical damage-couple viscoelastic constitutive formulation implemented in a finite element code are presented and illustrated by using the ABAQUS user material subroutine (UMAT). Then, an experimental procedure based on the Linear Amplitude Sweep test for obtaining the viscoelastic and damage parameters at a given temperature was conducted. An improved morphological multi-scale algorithm was employed to segment the adhesive coarse aggregate images. We developed a pixel-based digital reconstruction model of asphalt mixture with the X-ray CT image after being processed. Finally, the image-based FE model incorporated with damage-coupled viscoelastic asphalt mastic phase and elastic aggregates was used for the compressive test simulations successfully in this study. Simulation results showed that the damaged simulation results have a larger stress distribution compared with the undamaged simulation due to the irregularity of the coarse aggregates. The von Mises stress distribution is smaller as the loading time increases due to the viscoelastic behavior of asphalt mastic. It can also provide insight on the damaged mechanisms and the possible location in asphalt mixture where microscopic cracking would most likely occur. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Quantitative Analysis of the Blending Degree of Virgin and RAP Binders in Recycled Asphalt Mixtures with a High RAP Content
Appl. Sci. 2018, 8(12), 2668; https://doi.org/10.3390/app8122668 - 18 Dec 2018
Cited by 3
Abstract
Recycled asphalt mixtures (RAM), which are prepared by blending reclaimed asphalt pavement (RAP), virgin bitumen and mineral additives, provide a variety of advantages, including resource recycling, reductions in costs, and reduced negative environmental impacts. However, multiple agencies have expressed concerns about the utilization [...] Read more.
Recycled asphalt mixtures (RAM), which are prepared by blending reclaimed asphalt pavement (RAP), virgin bitumen and mineral additives, provide a variety of advantages, including resource recycling, reductions in costs, and reduced negative environmental impacts. However, multiple agencies have expressed concerns about the utilization ratio of RAP; thus, a comprehensive understanding of the blending degree of virgin and RAP binders in RAM would be significantly helpful for promoting the application of RAP. This study aims to quantitatively analyze the blending degree of virgin and RAP binders in RAM with high RAP contents. Carboxyl-terminated butadiene acrylonitrile (CTBN) was utilized as a tracer to mark the virgin bitumen; in addition, Fourier transform infrared (FTIR) spectroscopy was used to develop the structural index of CTBN (ICTBN). By establishing the standard curve between ICTBN and the CTBN content, the blending degree of virgin and RAP binders at different locations within RAM can be determined quantitatively. The study results indicate that the RAP binder was completely blended with the virgin bitumen in the outer RAP layer. However, the blending degree decreased with an increase in the RAP depth, and the blending degree in the inner RAP layer was only approximately half that which was found in the case of complete blending. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Pavement Performance Investigation of Nano-TiO2/CaCO3 and Basalt Fiber Composite Modified Asphalt Mixture under Freeze‒Thaw Cycles
Appl. Sci. 2018, 8(12), 2581; https://doi.org/10.3390/app8122581 - 12 Dec 2018
Cited by 4
Abstract
The objective of this research is to evaluate the pavement performance degradation of nano-TiO2/CaCO3 and basalt fiber composite modified asphalt mixtures under freeze‒thaw cycles. The freeze‒thaw resistance of composite modified asphalt mixture was studied by measuring the mesoscopic void volume, [...] Read more.
The objective of this research is to evaluate the pavement performance degradation of nano-TiO2/CaCO3 and basalt fiber composite modified asphalt mixtures under freeze‒thaw cycles. The freeze‒thaw resistance of composite modified asphalt mixture was studied by measuring the mesoscopic void volume, stability, indirect tensile stiffness modulus, splitting strength, uniaxial compression static, and dynamic creep rate. The equal-pitch gray prediction model GM (1, 3) was also established to predict the pavement performance of the asphalt mixture. It was concluded that the high- and low-temperature performance and water stability of nano-TiO2/CaCO3 and basalt fiber composite modified asphalt mixture were better than those of an ordinary asphalt mixture before and after freeze‒thaw cycles. The test results of uniaxial compressive static and dynamic creep after freeze‒thaw cycles showed that the high-temperature stability of the nano-TiO2/CaCO3 and basalt fiber composite modified asphalt mixture after freeze‒thaw was obviously improved compared with an ordinary asphalt mixture. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Comparison of Relaxation Modulus Converted from Frequency- and Time-Dependent Viscoelastic Functions through Numerical Methods
Appl. Sci. 2018, 8(12), 2447; https://doi.org/10.3390/app8122447 - 01 Dec 2018
Cited by 1
Abstract
Due to the difficulty of obtaining relaxation modulus directly from experiments, many interconversion methods from other viscoelastic functions to relaxation modulus were developed in previous years. The objectives of this paper were to analyze the difference of relaxation modulus converted from dynamic modulus [...] Read more.
Due to the difficulty of obtaining relaxation modulus directly from experiments, many interconversion methods from other viscoelastic functions to relaxation modulus were developed in previous years. The objectives of this paper were to analyze the difference of relaxation modulus converted from dynamic modulus and creep compliance and explore its potential causes. The selected methods were the numerical interconversions based on Prony series representation. For the dynamic to relaxation conversion, the time spectrum was determined by the collocation method. Meanwhile, for the creep to relaxation conversion, both the collocation method and least squares method were adopted to perform the Laplace transform. The results show that these two methods do not present a significant difference in estimating relaxation modulus. Their difference mostly exists in the transient reduced time region. Calculating the average of two methods is suggested to avoid great deviation of single experiment. To predict viscoelastic responses from creep compliance, the collocation method yields comparable results to the least squares method. Thus, simply-calculated collocation method may be preferable in practice. Further, the master curve pattern is sensitive to the Prony series coefficients. The difference in transient reduced time region may be attributed to the indeterminate Prony series coefficients. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Microstructure Analysis of Modified Asphalt Mixtures under Freeze-Thaw Cycles Based on CT Scanning Technology
Appl. Sci. 2018, 8(11), 2191; https://doi.org/10.3390/app8112191 - 08 Nov 2018
Cited by 2
Abstract
The modifiers NTC (nano-TiO2/CaCO3) and BF (basalt fiber) were adopted to modify a base matrix asphalt mixture. The base matrix asphalt mixture and three kinds of modified asphalt mixture under F–T (freeze–thaw) cycles were scanned by computed tomography. The [...] Read more.
The modifiers NTC (nano-TiO2/CaCO3) and BF (basalt fiber) were adopted to modify a base matrix asphalt mixture. The base matrix asphalt mixture and three kinds of modified asphalt mixture under F–T (freeze–thaw) cycles were scanned by computed tomography. The air voids and morphological changes of asphalt mixture were summarized by image processing technology, and the development process of F–T damage to asphalt mixture was explained from a micro-view. The porosity of NTC-modified asphalt mixture changed little, and the void distribution between base matrix asphalt mixture and NTC-BF (nano-TiO2/CaCO3 and basalt fiber) composite modified asphalt mixture was more uniform. The macro-pores in the asphalt mixture under 15 F–T cycles began to connect gradually, and the pore characteristics also changed. The number and shape of the pores changed under 15 F–T cycles. According to the state characteristics, the change amplitude of the pore characteristics of matrix asphalt mixture and NTC-BF composite modified asphalt mixture were the most stable under F–T cycles. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessArticle
Fatigue Resistance Characterization of Warm Asphalt Rubber by Multiple Approaches
Appl. Sci. 2018, 8(9), 1495; https://doi.org/10.3390/app8091495 - 31 Aug 2018
Cited by 17
Abstract
Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR [...] Read more.
Warm asphalt rubber (WAR) mixture is a sustainable paving material with advantages including waste recycling and noise reducing. A comprehensive understanding of the fatigue performance of WAR specimens is helpful to its wide application. However, research on evaluating the fatigue performance of WAR binder and mixtures is very limited. This paper applies five fatigue analysis approaches to evaluate the fatigue life of WAR samples with three different warm mix asphalt (WMA) additives. The conventional G*sinδ, linear amplitude sweep (LAS), indirect tensile fatigue test (ITFT), and four-point bending beam (4PB) test were conducted based on available standards. In addition, a novel shear fatigue test was performed on WAR mortars. Test results indicated that the incorporation of crumb rubber has a significantly positive effect on fatigue resistance. WAR with chemical and foaming additives exhibited a poorer performance than asphalt rubber (AR), but their fatigue performance was still greatly superior to the non-rubberized samples. Finally, LAS as well as mortar shear fatigue and 4PB tests provided the same prediction of fatigue resistance, while the results of G*sinδ and the ITFT were inconsistent. It is recommended to use LAS, the mortar shear fatigue test, and the 4PB test for the fatigue resistance evaluation of rubberized specimens. The validation of the findings with more materials and field performances is recommended. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessReview
A Review on Bitumen Rejuvenation: Mechanisms, Materials, Methods and Perspectives
Appl. Sci. 2019, 9(20), 4316; https://doi.org/10.3390/app9204316 - 14 Oct 2019
Abstract
This review aims to explore the state of the knowledge and the state-of-the-art regarding bitumen rejuvenation. In particular, attention was paid to clear things up about the rejuvenator mechanism of action. Frequently, the terms rejuvenator and flux oil, or oil (i.e., softening agent) [...] Read more.
This review aims to explore the state of the knowledge and the state-of-the-art regarding bitumen rejuvenation. In particular, attention was paid to clear things up about the rejuvenator mechanism of action. Frequently, the terms rejuvenator and flux oil, or oil (i.e., softening agent) are used as if they were synonymous. According to our knowledge, these two terms refer to substances producing different modifications to the aged bitumen: they can decrease the viscosity (softening agents), or, in addition to this, restore the original microstructure (real rejuvenators). In order to deal with the argument in its entirety, the bitumen is investigated in terms of chemical structure and microstructural features. Proper investigating tools are, therefore, needed to distinguish the different mechanisms of action of the various types of bitumen, so attention is focused on recent research and the use of different investigation techniques to distinguish between various additives. Methods based on organic synthesis can also be used to prepare ad-hoc rejuvenating molecules with higher performances. The interplay of chemical interaction, structural changes and overall effect of the additive is then presented in terms of the modern concepts of complex systems, which furnishes valid arguments to suggest X-ray scattering and Nuclear Magnetic Resonance relaxometry experiments as vanguard and forefront tools to study bitumen. Far from being a standard review, this work represents a critical analysis of the state-of-the-art taking into account for the molecular basis at the origin of the observed behavior. Furnishing a novel viewpoint for the study of bitumen based on the concepts of the complex systems in physics, it constitutes a novel approach for the study of these systems. Full article
(This article belongs to the Special Issue Asphalt Materials)
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Open AccessFeature PaperReview
Bitumen and Bitumen Modification: A Review on Latest Advances
Appl. Sci. 2019, 9(4), 742; https://doi.org/10.3390/app9040742 - 20 Feb 2019
Cited by 4
Abstract
This synthesis explores the state-of-the-knowledge and state-of-the-practice regarding the latest updates on polymer-modified bitumens (PmBs). The information in this study was gathered from a thorough review of the latest papers in the literatures related to modified bituminous materials, technologies, and advances. For this [...] Read more.
This synthesis explores the state-of-the-knowledge and state-of-the-practice regarding the latest updates on polymer-modified bitumens (PmBs). The information in this study was gathered from a thorough review of the latest papers in the literatures related to modified bituminous materials, technologies, and advances. For this purpose, the paper is presented in two principle sections. In the first part, the bitumen itself is investigated in terms of chemical structure and microstructural systems. In the second part, the paper focuses on bitumen modification from different aspects for assessing the effectiveness of the introduced additives and polymers for enhancing the engineering properties of bitumen in both paving and industrial applications. In conclusion, the knowledge obtained in this study has revealed the importance of the chemical composition of base bitumen for its modification. It can be declared that while some polymers/additives can improve one or some aspects of neat bitumen properties, they can lead to compatibility problems in storage and production. In this respect, several studies showed the effectiveness of waxes for improving the compatibility of polymers with bitumen in addition to some benefits regarding warm mix asphalt (WMA) production. Full article
(This article belongs to the Special Issue Asphalt Materials)
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