In recent years, flexible pavement construction technology has relied heavily on the use of reclaimed asphalt pavement (RAP). However, the brittle nature of RAP, which stems from the use of an aged ...asphalt, has introduced numerous complexities into the process, with important implications to pavement service life. The properties of the aged asphalt can be rejuvenated to improve the performance and the behavior of RAP mixtures. This paper presents a review of past works that have used rejuvenating materials with RAP, including their benefits and drawbacks, as well as the optimal approach to increase RAP content in asphaltic mixtures. The method of rejuvenating aged asphalt and the mechanism of rejuvenation are also reviewed. The findings of this review can be used to predict the current and future challenges in the regeneration of RAP mixtures using rejuvenating materials.
Environmental issues and fluctuations in the price of asphalt binders have increased the demand in usage of reclaimed asphalt pavement (RAP) material for asphalt mixtures. The RAP binder, ...nevertheless, is often highly aged and has several drawbacks, for instance, low cracking resistance, low workability, and low fatigue in the resulting mixtures. These issues can be resolved by using rejuvenators. As such, this research work assessed the engineering properties of reclaimed hot-mix asphalt (HMA) mixture rejuvenated by maltene-derived asphalt. The tests examined Marshall properties, moisture damage, resilient modulus (M
R
), dynamic creep, Cantabro loss, and rutting resistance, including the stripping and coating tests. The results showed that maltene had been effective in mitigating the aging effect of RAP asphalt, while the rejuvenated mixture exhibited considerable enhancement, especially when compared to the virgin and RAP mixtures without maltene. A simple cost analysis revealed that maltene was cost-effective as it compensated for the adverse effects of RAP, hence can be used to raise the content of RAP in asphalt mixture.
Reclaimed asphalt pavement (RAP) has received much attention recently due to its increased use in hot mix asphalt (HMA) pavements to enhance pavement sustainability. The use of aged asphalt in RAP, ...which is highly oxidised and has lost its properties due to exposure to traffic loads and climatic conditions throughout its lifespan, can cause asphalt mixtures to stiffen and embrittle, thus negatively affecting the behaviour of asphalt mixtures. This issue may be resolved by including rejuvenating agents that can restore both physical and rheological properties of aged asphalt by increasing maltene fractions and decreasing asphaltene. However, the high restoration capacity of any kind of rejuvenating agent does not assure the durability of restored aged asphalt. This study explored the performance and durability of rejuvenated asphalt mixtures embedded with several types of rejuvenators identified from the extensive literature review. The study serves as a significant reference to predict future challenges in rejuvenating aged asphalt.
Nanomaterials are small-sized materials between 1 and 100 nm which produce a greater surface area than common size materials. Coconut shell is one of the potential agricultural wastes to be used as ...nanomaterial due to its high strength and hardness. However, poor adhesion bonding was the problem of using this agricultural waste material as a modifier in the bitumen matrix. Therefore, in this study nanocarbon from coconut shell ash (NCA) was produced as bitumen modifier. NCA was produced and characterised using various techniques prior to be utilised at 0.0%, 1.5%, 3.0%, 4.5%, 6.0% and 7.5% by weight of bitumen PEN 60/70. The rheological test, using a dynamic shear rheometer (DSR), was performed on the unaged, rolling thin film oven and pressure ageing vessel samples. Subsequently, X-ray diffraction and atomic force microscopy were performed on the unaged samples. The DSR results revealed that NCA improved the rutting and fatigue cracking parameter of the bitumen. Also, the observations from microstructure properties showed that NCA delayed the ageing of the bitumen, produced a homogenous structure and increased the cohesion and adhesion properties of the bitumen. As a result, a strong bonding between the NCA and bitumen was formed and the properties of bitumen were altered.
Rejuvenating agents are considered desirable options in rejuvenating recycled asphalt's properties. Hence, the capability of integrating waste engine oil (WEO) and maltene to rejuvenate the traits of ...recycled asphalt was investigated. The penetration, softening point, ductility and viscosity were measured to determine an ideal amount of hybrid rejuvenating agent. Then, the rejuvenated asphalt was evaluated against different samples through maltene to asphaltene ratio, rolling thin film oven (RTFO), storage stability, dynamic shear rheometer (DSR) and bend beam rheometer (BBR) tests. Later, the Fourier Transform Infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA) and contact angle were employed. Based on the physical tests and the statistical analysis, the properties of recycled samples were restored approximately to that of the virgin asphalt by adding appropriate doses of hybrid rejuvenating agent. Meanwhile, the DSR and BBR results reported comparable performance between the rejuvenated and virgin samples. The hybrid rejuvenating agent has reduced the chemical ageing index and asphaltene content of the recycled asphalt. Moreover, TGA exhibited that the rejuvenated samples became more sensitive to temperature compared to recycled asphalt. In conclusion, 5% and 10% of the hybrid rejuvenating agent can renovate recycled asphalt for subsequent reuse in pavements depending on the characteristics of recycled asphalt.
Abstract The issue of road deterioration in Mosul, Iraq, has become a matter of concern for local communities. The instability of road surfaces under the stress of vehicular traffic necessitates ...significant intervention to mitigate and manage this problem. This study has developed an asphalt mixture by following the Bailey method for aggregate gradation. The impact of aggregate gradation on the mechanical properties of the asphalt mixture was thoroughly analysed. Additionally, two separate mixtures were conducted using the conventional Marshall method to assess indirect tensile strength, Marshall properties, and susceptibility to moisture damage. The primary objective of this research is to design an aggregate structure that acts as a robust unit capable of withstanding heavy loads, repeated stresses, and high temperatures. The findings of the study indicate that the asphalt mixture created using the Bailey method exhibited superior stability with values of 13.6 kN, compared to the two traditional mixtures (11.8 kN, 9.2 kN), and. However, it is worth noting that the flow values also indicated a relative preference for the Bailey method, with values of and 3.1 mm, compared with 3.85 mm and 3.2 mm of the traditional mixtures. The results of Tensile strength ratio further corroborated the efficacy of Bailey’s technique, with outcomes of 85.1 %, thus enhancing the applicability of this method. This observation is attributed to the concept of granular interlocking, which forms the foundation of the Bailey method.
This research addresses the significant challenge posed by early water damage in highway asphalt pavement, a critical concern affecting pavement service performance. To counteract this issue, the ...utilization of anti-stripping agents in asphalt is explored as a highly effective technical intervention. In this investigation, a carefully selected amine-free additive was employed to modify the asphalt binder. A comprehensive array of physical and rheological tests, covering aspects such as storage stability, penetration, softening point, ductility, elastic recovery, rolling thin-film oven, retained penetration, the ductility of residue, and rotational viscometer assessments, were conducted to examine the multifaceted impact of the anti-stripping agent on the asphalt binder. Additionally, we assessed the asphalt mixture’s sensitivity to moisture through Marshall stability tests after conditioning for 40 min and 24 h, followed by an enhanced immersion test and moisture susceptibility measurement. The results reveal a nuanced interplay of chemical and physical mechanisms influencing the behavior of the asphalt binder. Notably, the incorporation of an anti-stripping agent at a concentration of 0.25–0.5% (by weight of asphalt binder) led to a substantial improvement in the tensile strength ratio (TSR) to 94.9%, a noteworthy enhancement compared to the 80.6% observed with virgin asphalt mixture. Furthermore, the retained stability index (RSI) exhibited a remarkable increase to 98.1%, surpassing the 87.6% recorded for virgin asphalt. This study not only provides crucial insights into the intricate dynamics of asphalt binder performance but also emphasizes the pivotal role of anti-stripping agents in augmenting the structural integrity and resilience of asphalt pavement.
The wide application of reclaimed asphalt pavement (RAP) is hindered due to the highly brittle nature of the material, which contributes a major factor towards cracking-related distresses. While the ...utilisation of rejuvenating agents has been shown to enhance the flexibility of RAP, they also trigger certain negative effects on the performance of asphalt mixtures. In view of this, potential rejuvenators should be able to alter the rheological properties of asphalts to limit fatigue issues and enhance the potential of low-temperature cracking. Therefore, this study aimed to investigate the possibility of extraction and characterisation of maltene from virgin asphalt (VA) as a potential rejuvenating agent in RAP. Several physicochemical characteristics were examined, including density, viscosity, gas chromatography–mass spectrometry (GC–MS), Fourier-transform infrared (FTIR) spectroscopy, CHNS elemental analysis, and energy dispersive X-ray (EDX) analysis. Finally, the stiffness modulus characteristics of the different types of asphalt binders were evaluated at low and high temperatures. The results demonstrated that maltene was successfully extracted from VA using petroleum ether. In addition, the GC–MS showed that the extracted maltene contained polar and non-polar compounds with low molecular weights compared to VA. Furthermore, the spectra curve of maltene was very similar to that of asphalt, indicating its compatibility with asphalt binder and prospective use. Finally, adding maltene to aged asphalt decreased stiffness values to 0.0063, 0.0499, and 0.0108 MPa, which are equivalent to VA values (0.0061, 0.0481, and 0.0104 MPa) at loading times of 1.0, 0.1, and 0.55 s, respectively. Meanwhile, the stiffness modulus characteristics at low temperature were restored with the addition of maltene.
The properties of aged asphalt can be renewed using rejuvenating agents. Rejuvenators can improve the performance of reclaimed asphalt pavement (RAP) by reducing the asphaltene-to-maltene ratio back ...to their initial state. This study assessed the function of maltene as a rejuvenator to renew aged asphalt. Penetration, softening point, ductility and viscosity tests were performed to determine the ideal maltene content to be incorporated into RAP. The rejuvenated asphalt samples were evaluated using rolling thin film oven (RTFO), dynamic shear rheometer (DSR), bending beam rheometer (BBR), Fourier transform infrared (FTIR), thermogravimetric (TGA) and atomic force microscopy (AFM) measurements. The outcomes were compared with virgin and aged asphalts. Both oxygenated groups and asphaltene content decreased by adding 12% maltene. Essentially, DSR, BBR, TGA, and AFM analyses divulged the comparable performance of rejuvenated asphalt with virgin asphalt, signifying the potency of maltene for practical applications.
A good asphalt mixture is very important to maintain the triangle of sustainability. Many accidents occur due to pavement damage such as permanent deformation caused by the external loads induced by ...heavy traffic. Stone Mastic Asphalt (SMA) has a low resistance to moisture and other performances. Many researchers have conducted on SMA using various types of fiber. However, not much research has been done using steel fiber in the SMA mixture and has analyzed the result obtained using a statistical approach. The objective of this research was to identify the optimum amount of steel fiber in a modified asphalt mixture and characterize the performance of steel fiber in the SMA mixture using the statistical approach of Response Surface Methodology (RSM) in Design Expert Software. In this study, various steel fiber proportions of 0 percent, 0.3 percent, 0.5 percent, and 0.7 percent by the total weight of the SMA mixture were used. The Marshall stability and flow test, dynamic creep and moisture susceptibility test, and ultimately, RSM analysis were used to evaluate the properties and performance of the steel fiber-modified SMA, which contained 6.2 percent of PEN 60/70 asphalt binder content. The testing findings unmistakably demonstrated that the addition of steel fiber greatly improves the SMA mixture’s resistance to moisture and permanent deformation. An amount of 0.3 percent was found to be the most optimum steel fiber content from the optimization by using Response Surface Methodology, thus proven with additional steel fiber in the SMA mixture enhancing the performance of the mixture. As a result, it can be determined that the addition of steel fiber to SMA asphalt mixtures has improved the properties and performance in the construction of asphalt pavements, and the RSM method is an efficient statistical method for producing an appropriate empirical model for relating parameters and predicting the best performance of an asphaltic mixture.
PDF
