Dynamic Shear Rheological Test Research Articles

Towards the high RAP dosage obtained by refined processing influence on comprehensive performance of recycled asphalt mixture

The severe agglomeration of Reclaimed Asphalt Pavement (RAP) particles not only leads to high gradation variability during recycling, but also impedes the miscibility between new-old binders. This phenomenon imposes significant limitations on maximizing the utilization of RAP with high content and value. This paper first realized the effective separation of asphalt milling material by the self-developed RAP refined processing equipment to obtain coarse RAP with low binder content and fine RAP with high binder content. The fine RAP with high binder content underwent a deep rejuvenation process, and the recovery efficiency of the asphalt mortar was evaluated by CT scanning test, microscope observation test, and dynamic shear rheology test. Moreover, to investigate the strength formation characteristics of recycled asphalt mixtures with high RAP content, specific tests including wheel tracking test, three-point bending test, Hamburg Wheel Tracking test, dynamic modulus test, and two-point bending fatigue test, were conducted. By using the refined processing equipment, the asphalt film on the RAP can be precisely removed, thereby addressing the issue of aged binder agglomeration. In the coarse RAP with low binder content, the binder content was reduced to 1.48 %, allowing it to be used as a direct substitute for new aggregate, whereas the binder content of fine RAP exceeded 10 %. It was found that the direct incorporation of unrefined RAP enhanced the high-temperature stability and dynamic modulus of recycled asphalt mixture, but impacted their low-temperature cracking resistance, moisture stability, and fatigue performance. After refined processing and differentiated recycling design, the agglomeration of aged binder was reduced and the miscibility of new-old binders was improved, effectively enhancing the comprehensive performance of the recycled asphalt mixture. It should be noted that the mixing homogeneity and miscibility decrease as the RAP content exceeds 75 %, resulting in the reduction of moisture stability, cracking resistance, and fatigue performance of recycled asphalt mixture.

Effects of bonding enhancers on shear stress and bonding strength of modified asphalt binders under different aging and moisture conditions

Insufficient bonding within pavement material causes widespread propagation of traffic-induced stresses, leading to accelerated damage accumulation and significant reduction in the service life of flexible pavements. This research aimed to examine the effects of using bonding enhancers, specifically Polyalkylene Glycol-based (PLG) and Alkylamines-based (ALM), on modified asphalt binders to improve the bonding characteristics. These additives were utilized at different concentration levels, i.e., 0.5 % and 1.0 %, based on the mass of asphalt binders, with the aim of enhancing the bonding performance between the materials within the asphalt mixture composite. The effectiveness of the modified asphalt binders was compared to the conventional ones through laboratory tests, which included shear-compression and pullout tests. These tests were conducted to assess the bonding performance of the modified asphalt binders by preparing different sets of sandwich samples using concrete cube substrates. A sodium carbonate solution was used as a medium to accelerate the effect of moisture damage on samples during the conditioning process. Additionally, the bonding performance of the asphalt binders was evaluated through a series of pullout and shear-compression tests under designated moisture and aging conditions. The dynamic shear rheological (DSR) test results of Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV)-aged binders incorporating bonding enhancers showed superior resistance to rutting and fatigue failure. Significant improvements in stress and shear strength were observed under moisture and aging conditions, highlighting improvements in the bonding performance of the modified asphalt binders. The incorporation of additives has positively contributed to the pavement performance, despite only a modest increase in bonding performance, tensile strength, and shear stress resistance.

Study on the Performance of Modified Qingchuan Rock/Rubber Asphalt

This paper developed a new environmentally friendly composite modified asphalt material and studied the composite modification of Qingchuan rock asphalt (QRA) and waste tire rubber powder (RP) was studied in this paper. QRA/RP composite modified asphalt was prepared by adding these two materials as modifiers into matrix asphalt and compared with matrix asphalt and QRA modified asphalt. The basic properties of asphalt before and after aging were evaluated by the rotating thin film oven test. The high-temperature performance and permanent deformation resistance at different temperatures and frequencies were analyzed by the dynamic shear rheological test. The bending creep stiffness test was used to evaluate the low-temperature performance. In addition, the microstructure and modification mechanism of composite-modified asphalt were analyzed by scanning electron microscopy and infrared spectroscopy. The results show that QRA-modified asphalt is superior to matrix asphalt in terms of mass loss, viscosity ratio, and residual penetration, while QRA/RP composite-modified asphalt is further improved on this basis, QRA/RP composite modified asphalt can effectively improve the high and low temperature performance of asphalt.. Although the addition of RP is mainly based on physical modification, it also causes weak chemical reactions and enhances the adhesion of asphalt. The interaction between Qingchuan Rock asphalt and rubber powder significantly improves the overall stability of asphalt structure.

Analysis of viscoelastic rheological properties and storage stability of solvent cold patching asphalt

Solvent cold patching asphalt (CPA) is commonly mixed with aggregate for rapid pavement pothole repairing in cold and wet seasons, as its ordinary temperature fluidity and gradually increased viscosity. Currently, the evaluation criteria and expectations for the CPA are often related to the modified asphalt without considering the metastable viscoelastic properties of CPA required to ensure the preparation and storage effectiveness. This paper selects diesel oil, kerosene, aromatics solvent oil and isomeric hexadecane four solvents to prepare CPAs, and investigates the viscoelastic properties and storage stability of CPAs with considering the storage time, temperature and solvents incorporation proportion based on penetration test, viscosity test and dynamic shear rheological test. The experimental results show that the optimal dosage of the four diluents is 20%, among which IH-CPA has better storage stability at 30℃, and its 30d viscosity change is the smallest, which is 19.2%. Moreover, the interaction mechanism between solvent and asphalt is explored through molecular simulation model. The research outcome shows that findings from this research can contribute to a better understanding of the metastable structure of CPA, and furnish the high-performance CPA production and storage strategies.

Degradation performance and mechanism of VOCs in asphalt by alkali metal-doped La2Ce2O7-based fluorite through pyroelectric and photocatalytic synergy

Under high-temperature construction conditions, the use of asphalt can release a large amount of volatile organic compounds (VOCs), which has adverse effect on the environment and human health. Part of fluorite oxides show potential application in VOCs conversion due to their excellent photoresponse and chemical stability in addition to ferroelectricity, piezoelectricity and pyroelectricity properties. In this paper, La2Ce2O7-based fluorite was modified with alkali metal doping and its photo-thermal coupling catalytic effects on the degradation performance of VOCs in asphalt were investigated. The results show that the fluorite catalysts La1.85A0.15Ce2O7 (A=Li, Na, K, Rb, Cs) have efficient electron-hole pair separation ability. Among them, the Rb+ doped La2Ce2O7 sample not only has stronger pyroelectric effect due to increased lattice distortion and oxygen vacancies, but also has the best photogenerated charge transport property and more favorable valence band position for oxidation reaction. Under the photo-thermal synergistic effect, the catalytic degradation performance of VOCs in asphalt by Rb+ doped La2Ce2O7 catalyst can reach 82.61 % at 50 min. Additionally, dynamic shear rheological tests indicate that the addition of catalysts at this blending ratio can enhance the rutting resistance of the asphalt material. This study introduces an innovative approach to enhance the efficiency of multi-field coupled degradation processes of volatile organic compounds (VOCs) in asphalt.

The Rejuvenation Effect of Bio-Oils on Long-Term Aged Asphalt.

Generally, rejuvenators are used to supply missing components of aged asphalt, reverse the aging process, and are widely used in asphalt maintenance and recycling. However, compared with traditional rejuvenators, bio-oil rejuvenators are environmentally friendly, economical and efficient. This study looks into the effect of the three different bio-oils, namely sunflower oil, soybean oil, and palm oil, on the physical properties, rheological properties and chemical components of aged asphalt at different dosages. The asphalt physical properties and Dynamic Shear Rheological (DSR) test results show that with the increase in bio-oil, the physical properties and rheological properties of rejuvenated asphalt are close to those of virgin asphalt, but the high-temperature rutting resistance needs to be further improved. The results of Fourier Transform Infrared Spectroscopy (FTIR) show that the carbonyl and sulfoxide indices of rejuvenated asphalt are much lower than those of aged asphalt. Moreover, the rejuvenation efficiency of aged asphalt mixed with sunflower oil is better than that with soybean oil and palm oil at the same dosage.

Effects of Silicone Rubber on Rheological Properties and Aging Characteristics of Asphalt Binder.

Silicone rubber (SR) is a kind of polymer insulation material with excellent performance. With the service life of silicone rubber products reaching the limit, how to dispose of waste silicone rubber is an urgent problem to be solved. In this paper, silicone rubber-modified asphalt binder (SRMA) was prepared by SR and 90# base asphalt binder. The simulated short-term aging and long-term aging tests of SRMA were carried out using the thin film oven aging test (TFOT) and pressure aging vessel test (PAV). The rotary viscosity test and dynamic shear rheological test (DSR) were applied to the rheological properties of SRMA before and after aging. The degradation degree and chemical composition changes of SR were explored by the toluene insoluble matter test, Fourier transform infrared spectroscopy (FTIR), and a Fluorescence microscope (FM). The results demonstrate that SR can significantly affect the aging resistance, fatigue life, and high-temperature stability of SRMA. As the content of SR rose, the elastic component in SRMA increased, leading to a nice performance in stability at high temperatures and fatigue resistance. However, excessive content (14%wt and 16%wt) had a negative influence on the performance of SRMA. So, the optimal content was speculated to be between 12% and 14%. Furthermore, SR and asphalt binder would be aged and degraded together in the aging process, and this phenomenon was more obvious during long-term aging.

Investigation of the Properties of High-Viscosity Modified Asphalt Binder under Hygrothermal Environments.

High-viscosity modified asphalt binder (HVMA) is used widely as a polymer-modified binder in porous asphalt pavement because it can improve the cohesiveness of the asphalt mixture. However, because of the high voidage in the mixture, HVMA is vulnerable to aging induced by temperature, oxygen, water, sunlight, and other climatic conditions, which degrades the performance of pavement. The properties of asphalt binder are affected adversely by the effects of hygrothermal environments in megathermal and rainy areas. Therefore, it is essential to study the aging characteristics of HVMA under the influence of hygrothermal environments to promote its application as a high-viscosity modifier. A hygrothermal cycle aging test (HCAT) was designed to simulate the aging of HVMA when rainwater was kept inside of the pavement after rainfall in megathermal areas. One kind of base bitumen and three kinds of HVMA (referred to as SBS, A, and B, respectively) were selected in this study. Short-term aging tests, hygrothermal cycling aging tests, and long-term aging tests were performed on the base bitumen and three kinds of modified asphalt binder. Fourier-transform infrared spectroscopy (FTIR), thermo-gravimetric analysis (TGA), and dynamic shear rheological (DSR) tests were used to evaluate the properties of the binders on the micro and macro scales. By comparing the index variations of the four binders before and after aging, the effects of the hygrothermal environment on the properties of HVMA were studied. It was found that the effects of the hygrothermal environment expedited the decomposition of the polymer and the formation of carbonyl groups compared with the TFOT and PAV test, which TGA confirmed further. Moreover, the thermal stability of the samples was improved after HCAT. In addition, the master curves of the complex modulus showed that hygrothermal cycles made the high-temperature rutting resistance of asphalt binder increase significantly. All of the results above verified that the effect of hygrothermal cycling could accelerate the aging of HVMA and shorten its service life.

Study of High-Temperature Rheological Properties of Emulsified Asphalt Residues

The residue of emulsified asphalt is its final state when it becomes part of an asphalt mixture. Therefore, the mechanical properties of the residue have a significant impact on the performance of emulsified asphalt mixtures. Dynamic shear rheological tests and fluorescence microscopy were conducted to explore the effects of emulsification and aging on the rheological properties and micro-morphology of emulsified asphalt residue. The results of both the temperature sweep and multiple stress creep recovery tests indicated that the emulsification of the asphalt had different effects on the rheological properties of the base asphalt and the styrene-butadiene-styrene (SBS)-modified asphalt. For the base asphalt, emulsification increases the complex shear modulus by about 5% and reduces irrecoverable creep flexibility by 30%. However, the physical grinding effect of the colloid mill during the emulsification process could destroy the internal spatial network structure of SBS, leading to a reduction in the complex shear modulus by about 5% and a 10% increase in irrecoverable creep flexibility. This phenomenon is similar to the aging of SBS-modified asphalt, which, in turn, leads to a decline in the performance of emulsified SBS-modified asphalt residues.

Friction Characteristics and Lubrication Properties of Spherical Hinge Structure of Swivel Bridge

A spherical hinge structure is a key swivel bridge element that must be considered when evaluating friction characteristics and lubrication properties to meet the rotation requirement. Polytetrafluoroethylene (PTFE)-based spherical hinge sliders and lubrication coating have been employed for over 20 years, but with the growing tonnage of swivel bridge construction, their capacity to accommodate the required lubrication properties can be exceeded. In this manuscript, the optimal friction coefficient of the spherical hinge is obtained through the finite element analysis method. Four lubrication coatings and four spherical hinge sliders are prepared and tested through a self-developed rotation friction coefficient test, four-ball machine test, dynamic shear rheological test, and compression and shear performance test to evaluate the lubrication and friction properties of the spherical hinge structure. The results of the finite element analysis show that the optimum rotation friction coefficient of the spherical hinge structure is 0.031–1.131. The test results illustrate that the friction coefficient, wear scar diameter, maximum non-seize load, phase transition point, and thixotropic ring area of graphene lubrication coating are 0.065, 0.79 mm, 426 N, 14.6%, and 64,878 Pa/s. The graphene lubrication coating has different degrees of improvement compared with conventional polytetrafluoroethylene lubrication coating, showing more excellent lubrication properties, bearing capacity, thixotropy, and structural strength. Compressive and shear tests demonstrate that polyether ether ketone (PEEK) has good compressive and shear mechanical properties. The maximum compressive stress of PEEK is 87.7% higher than conventional PTFE, and the shear strength of PEEK is 6.07 times higher than that of PTFE. The research results can provide significantly greater wear resistance and a lower friction coefficient of the spherical hinge structure, leading to lower traction energy consumption and ensuring smooth and precise bridge rotation.

Rheological properties of warm mixed high viscosity asphalt at high and low temperatures.

The rheological properties of asphalt can well reflect its road performance, but the rheological properties of warm mix high viscosity asphalt (HVA) are unclear. In order to study the effect of warm mixing agent on rheological properties of HVA, two kinds of warm mixing agent EC120 (EC) and Evotherm M1 (M1) were selected to prepare warm mix HVA. The rheological properties of warm mix HVA at high temperature (135~195°C), medium temperature (0~80°C) and low temperature (-6~18°C) were studied by Brinell rotary viscosity test, dynamic shear rheological test (including temperature scanning, frequency scanning, linear amplitude scanning) and bending beam rheological test. The test results show that both EC and M1 have good viscosity reduction effect on HVA at high temperature, and can effectively reduce the construction temperature. At medium temperature, M1 can effectively improve the fatigue resistance of HVA, and the fatigue life can be increased by about 30% when the dosage is 0.6%. EC can increase the rutting factor of HVA and improve its resistance to deformation, but it will reduce its fatigue performance. When the dosage is 4%, the fatigue life will be reduced by about 9%. At low temperature, M1 can reduce the creep stiffness S, increase the creep rate m, and improve the low temperature performance of HVA, while EC has the opposite effect, weakening the low temperature performance of HVA. The results are helpful to understand the rheological properties of warm mix HVA and promote its application.

Effect of non-thermal effects in microwave heating on the rheology and chemical properties of petroleum asphalt

This study systematically analyses the rheological properties of typical petroleum asphalt heated by microwaves at different temperatures through viscosity, penetration, dynamic shear, low-temperature bending, and other rheological tests. The results show that the non-thermal effect of microwaves enhances the fluidity of petroleum asphalt in the high-temperature viscous flow state, becomes softer in the medium-temperature viscoelastic state, and becomes hard and brittle in the low-temperature glassy state. The effect of microwaves also causes some specific changes in the properties of bitumen, including softening point and glass transition temperature in the opposite direction, as well as a large difference in the response of bitumen of different viscosities. The chemical changes in microwave-heated bitumen were analyzed using component tests and microscopic observation. It was found that microwave heating homogenized and dispersed the asphaltene aggregates into small particles, with the heavy components significantly reduced and the light components increased.

Enhancing the physical properties of styrene-butadiene-styrene (SBS)-modified asphalt through polyetheramine-functionalized graphene oxide (PEA-GO) composites

To enhance the dispersion of graphene oxide (GO) in Styrene-butadiene-styrene (SBS) modified asphalt (SA) and the comprehensive physical properties of GO/SBS-modified asphalt (GSA), PEA-GO composites were prepared by grafting polyetheramine (PEA) onto GO for the preparation of PEA-GO/SBS-modified asphalt (PGSA). In this study, the chemical structure of PEA-GO was examined using fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The conventional properties of GSA and PGSA were analyzed. The effects of GO and PEA-GO on the high and low-temperature prevalent properties of SA were investigated by dynamic shear rheology (DSR) test and bending beam rheology (BBR) test. The adhesion properties of GSA and PGSA were investigated by surface free energy theory (SFE). The surface micro-morphology of GSA and PGSA and the dispersion state of GO in SA were analyzed using atomic force microscopy (AFM) and fluorescence microscopy (FM). The results showed that the characteristic absorption peaks of N-H, CH2-CH2, and C-N appeared in the FTIR diagram of PEA-GO. A new peak appeared in the XPS diagram: C-N. The high-temperature performance, low-temperature crack resistance, and adhesion of PGSA were superior to those of GSA. The size of the "bee structure" in PGSA is larger than in GSA, and PEA-GO demonstrates uniform dispersion in SA. This study serves as a reference for fine-tuning graphene oxide (GO) at the microscopic level to enhance the physical properties of GSA.

Study on Rheological Properties and Modification Mechanism of Budun Rock Asphalt/Nano-Silica Composite Modified Asphalt

To enhance the high and low-temperature performance of asphalt materials and extend the service life of asphalt pavement, two types of external admixtures, Butonite rock asphalt, and nano-silica are added to the asphalt. By conducting dynamic shear rheological tests and bending creep stiffness tests, the high and low-temperature rheological properties of Budun rock asphalt/nano-silica composite-modified asphalt were evaluated. The distribution of Budun rock asphalt and nano-silica in asphalt was studied using scanning electron microscopy and infrared spectroscopy tests, revealing the synergistic modification mechanism of Budun rock asphalt and nano-silica. The results show that the optimal dosage of Butonite rock asphalt and nano-silica composite-modified asphalt is 25% and 5%, respectively. At this dosage, the rutting factor G*/sinδ of composite-modified asphalt at 82 °C Compared with the matrix asphalt, the frequency main curve of Budun rock asphalt/nano-silica composite-modified asphalt is higher than that of the matrix asphalt and nano-silica-modified asphalt by 4 kPa. The creep modulus S at −18 °C decreases by 117.2 MPa, indicating that the high-temperature performance, low-temperature performance, and temperature sensitivity of Budun rock asphalt/nano-silica composite-modified asphalt are significantly improved compared to the matrix asphalt; The distribution of nano-silica particles in Budun rock asphalt/nano-silica composite-modified asphalt is uniform, and together with Budun rock asphalt, it forms a stable three-dimensional network skeleton structure; Budun rock asphalt/nano-silica composite-modified asphalt has generated new functional groups, and the blending process is mainly based on physical reactions, supplemented by weak chemical reactions.

Investigation on One-Component Waterborne Epoxy Emulsified Asphalt (OWEEA) Used as Bonding Material

Due to the issue of weakened adhesion between ultra-thin surface overlays, higher demands have been placed on bonding layer materials in practical engineering. This study proposed a method for preparing a one-component waterborne epoxy resin-modified emulsified asphalt (OWEEA) and explored the impact of different ratios on its performance. The basic physical and mechanical properties of the OWEEA, as well as its rheological characteristics, were investigated through penetration tests, softening point tests, ductility tests, tensile tests, and dynamic shear rheological tests. Pull-out tests and shear tests considering different substrates were used to evaluate the interfacial bonding performance of the OWEEA as a bonding layer material, and comparative analysis was conducted with conventional waterborne epoxy resin-modified emulsified asphalt. Based on microscopic testing and analysis, the laws of physical and chemical changes and secondary curing characteristics of the one-component waterborne epoxy emulsion (OWE) during the modification of emulsified asphalt were elucidated. The results indicated that the OWE prepared in this study significantly enhanced the tensile strength and bonding properties of emulsified asphalt. The results showed that the tensile strength, bonding strength, and shear strength of the OWEEA increased from 0.15 MPa, 0.36 MPa, and 0.35 MPa to 0.55 MPa, 1.29 MPa, and 2.01 MPa, respectively. The modification effect of the OWEEA surpassed that of conventional waterborne epoxy emulsion, albeit with a certain reduction in elongation at break, reduced from 1551% to 98%. Furthermore, the OWEEA showed a distinct secondary curing phenomenon. The results of the SEM tests showed that high temperatures accelerated the formation of the crosslinked network structure of OWE, promoting its integration with emulsified asphalt and resulting in a more uniform and dense structure, significantly enhancing bonding strength in a short period. In the actual road construction process, laying hot-mix asphalt mixtures on the bonding layer can further enhance its curing effect and improve its bonding performance.

Research on high and low temperature rheological properties of TPU/SBR composite modified asphalt

In road engineering, SBS modifier has been widely applied in China to enhance the quality of asphalt pavement. However, without considering the physical and chemical properties of SBS modifier and the asphalt substrate, alternative polymerization methods for asphalt modification that offer better performance and economic benefits have not been explored. In this study, an approach was taken to compound modify the base asphalt by incorporating Thermoplastic polyurethane (TPU) and Styrene Butadiene Rubber (SBR). The high and low temperature rheological properties of the modified asphalt were examined using tests such as Rotational Viscosity (RV) test, Dynamic Shear Rheological test (DSR), Multiple Stress Creep Rheological test (MSCR), and Bending Beam Rheological test (BBR). The modification mechanism of the mixed modified asphalt, combining SBR and TPU, was investigated through fluorescence microscope testing. The RV test revealed that the inclusion of TPU and SBR enhanced the viscosity of the asphalt to a certain extent, affording it favorable workability during construction and improved resistance against high temperature deformation. DSR and MSCR tests demonstrated that the incorporation of TPU significantly bolstered the external load resistance, deformation recovery, rutting resistance, and overall stability of the SBR modified asphalt under high temperature conditions; The BBR test proves that the composite modified asphalt has excellent low temperature crack resistance. The FM tests have shown that TPU are effective in reducing the segregation that may occur in SBR-modified asphalt, thus improving the performance of the composite modified asphalt.

Preparation and modification mechanism study of microwave-treated crumb rubber and waste engine oil-modified asphalt.

The objective of this study was to characterize the performance of waste engine oil (WEO) and microwave-treated crumb rubber (CR)-modified asphalt (WEO-MCRA) and analyze the modification mechanism. The viscosity and dynamic shear rheological (DSR) tests were carried out to evaluate the viscoelasticity property of WEO-MCRA. The storage stability and fluorescence microscope (FM) tests were used to characterize the compatibility of the components. The Fourier transform infrared spectroscopy (FTIR) and molecular dynamic simulation were introduced to analyze the change of function groups and modification mechanism. The results demonstrated that introducing Wt.20% CR treated with microwave and Wt.6% WEO obtained a lower viscosity, excellent storage stability, and satisfactory elasticity properties of asphalt. The morphology of modifiers presented a thread-like structure microscopic with the range of WEO content Wt.3%-Wt.6%. Molecular dynamic simulations revealed that the aromatic may be intensively absorbed by CR and increase the likelihood of phase separation. WEO reduced the binding energy of CR to aromatic from 178.0 to 151.5kcal/mol, which will contribute to the disaggregation of CR clusters. The diffusion coefficient shows a more obvious decrease with the addition of WEO and microwave treatment, which will benefit the stability of the asphalt. This study can provide a reference for the recycling of CR and WEO.

Effect of warm mix agent on the chemo-mechanical performance of binder with different oil sources

In this study, three typical oil source asphalt binders, Karamay asphalt A, CNOOC 36-1 asphalt B, Qinhuangdao CNPC asphalt C, were selected to prepare asphalt binders together with the warm mix agent Evotherm M1. The effects of warm mix agents on asphalt from different oil sources were experimentally studied via dynamic shear rheological (DSR), thermogravimetric analysis (TG), and Raman spectroscopy tests. The asphalt binders with different oil sources exhibit different properties. The rheological test results indicate that the addition of warm mix agent can slow down the decrease of asphalt viscosity during the aging process and the aging of asphalt. The results of the thermogravimetric test showed that the residual mass of asphalt with the addition of a warm mix agent significantly decreased after aging. Warm mixing agents can slow down the conversion of lightweight components to heavy components during the aging process of asphalt. By calculating the reflectivity of asphalt in Raman spectroscopy, it can be concluded that the reflectivity of asphalt decreases after adding a warm mix agent. The warm mixing agent reduces the degree of thermal evolution of asphalt. Warm mixing agents can make the chemical components in asphalt relatively stable and less prone to further pyrolysis or cracking reactions.

Evaluating the Effects of RA on the Rheological Properties and Aging Susceptibility of RAM Asphalt

Recycling agents (RAs) can mitigate the adverse effects of reclaimed asphalt pavement (RAP) on recycled asphalt, which can result in more RAP being added. To explore the effects of four RAs on recycled asphalt, this study used asphalt rheological performance experiments, including the bending beam rheometer (BBR) test, the dynamic shear rheological (DSR) test, and the indirect tensile asphalt cracking test (IDEAL-CT), to study the performance grade (PG), cracking resistance, and cracking susceptibility of recycled asphalt. In addition, an aging model for asphalt was used, and short-term and long-term aging sensitivities were evaluated according to this model. Results showed that US Soybean significantly enhanced the high-temperature and low-temperature performance grade (PGLT) and cracking resistance and reduced cracking sensitivity of the recycled asphalt. In addition, the short-term aging sensitivity was the lowest. It showed the best regeneration effect. However, the recycled asphalt with US Soybean showed the highest long-term aging sensitivity, suggesting that longer aging time results in poorer performance. Ingevity’s PG, cracking resistance, and cracking sensitivity are slightly lower than that of US Soybean, and Ingevity demonstrated the second lowest short-term aging sensitivity. However, its prolonged aging sensitivity was much lower than that of US Soybean. Asphalt and Wax Innovations and Georgia Pacific agents slightly improved recycled asphalt properties. The long-term aging sensitivity of recycled asphalt with four Ras was higher than that of recycled asphalt without Ras. These results indicated that the recycled asphalt’s performance with Ras worsened as aging time increased compared to the original recycled asphalt.

Application of the Air-Jet Laser Detection Technology for Asphalt Binders

AbstractA fast and convenient technique for Asphalt Binders was proposed in this paper, which was based on air-jet pressurized and laser to detect the transient deformation and creep recovery of asphalt. Taking five kinds of asphalt and modified asphalt commonly used in China as the research objects, the performance of asphalt were tested and analyzed by adopting the Penetration Test, Dynamic Shear Rheological (DSR) Test, Multiple Stress Creep and Recovery (MSCR) Test and the proposed test technology. The results verified the feasibility of the proposed test technology and the correlation between the traditional tests and the proposed test technology. The results demonstrated that the proposed test technology had good discrimination ability for different kinds of asphalt and could effectively reflect the performance differences. The new test protocol was similar to the Penetration Test. There was a significant correlation between the maximum deformation index and penetration index. The correlation coefficient was above 0.8, and the p value was much less than 0.01. It could be used as a possible alternative to the Penetration Test. The proposed new test was relatively convenient and fast compared with the dynamic shear test. There was a linear correlation between the maximum deflection index and the complex shear modulus G*, and the correlation coefficient between the recovery index and the phase angle is above 0.8, which indicated that the proposed new test and the DSR test had a significant correlation. There was also a good correlation between the creep recovery index of MSCR test and the recovery data of the proposed new test method. The research results provided a new solution for the performance test and evaluation of asphalt in China.