Low Temperature Rheological Properties Research Articles

Research on the Rheological Performance of Fast-Melting SBS-Modified Asphalt under Complex Environmental Factors

Currently, fast-melting SBS (Styrene-Butadiene-Styrene)-modified asphalt is widely used in pavements. However, in practical applications, complex environmental factors accelerate the deterioration of asphalt material properties, significantly affecting the service life of roads during their operational period. This study aims to examine the effects of complex environmental factors, including thermal oxidation, ultraviolet radiation, and various concentrations of salt solutions, on the high and low-temperature rheological properties of fast-melting SBS-modified asphalt (abbreviated as SBS-T-modified asphalt). Pressure aging–ultraviolet aging coupling and pressure aging–ultraviolet aging different concentration salt solution coupling were selected as the aging groups to simulate complex environmental conditions. Additionally, base asphalt and pressure-aged asphalt were used as control groups. The rheological properties of SBS-T-modified asphalt were evaluated using a dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results indicate that multiple-factor coupling aging reduces both the high-temperature and low-temperature performance of SBS-T-modified asphalt compared to single-factor aging, although the impact on rheological properties is not consistent across all conditions. After the combined effects of UV aging and pressure aging, the rutting resistance and high-temperature performance of SBS-T-modified asphalt are most severely impacted. However, when coupled with salt-solution aging, the rutting resistance of SBS-T-modified asphalt improves, with the complex modulus increasing by approximately 30%. This indicates that the presence of the salt solution enhances the high-temperature performance of the asphalt. An analysis of the low-temperature rheological properties of SBS-T-modified asphalt based on Burgers model shows that the low-temperature rheological performance of SBS-T-modified asphalt worsens under three-factor coupling aging compared to two-factor or single-factor aging, leading to poorer crack resistance. Notably, after adding salt solutions, the thermal sensitivity of SBS-T-modified asphalt increases significantly, with the ΔTc value decreasing approximately sixfold for every 2% increase in salt concentration.

Study on the performance of ground melon vine straw fiber modified asphalt

In order to reduce the waste of resources and the pollution of ecological environment caused by the large amount of waste crop straw accumulation or incineration, and to realize the high-value utilization of waste straw resources, this paper adopts the mechanical crushing method, acid and alkali solution treatment method to prepare the groundnut seedling straw fibers, and compares and analyzes the micro-morphology and chemical composition and thermal stability of the groundnut seedling straw fibers prepared by the physical method, the NaOH solution method, and the HCL solution method, through the scanning electron microscope, infrared spectroscope and the thermogravimetric analysis test; secondly, the optimal blending range of the groundnut seedling straw fibers is preferred. Secondly, the optimal dosage range of ground melon vine straw fiber was selected, the preparation process of ground melon vine straw fiber modified asphalt was proposed, five different dosages of ground melon vine straw fiber modified asphalt were prepared, and the basic properties, viscosity and temperature characteristics, and storage stability of ground melon vine straw fiber modified asphalt were analyzed; and then, a dynamic shear rheometer was used. Dynamic Shear Rheometer and Bending Beam Rheometer tests were used to study the high and low temperature rheological properties and resistance to permanent deformation of ground melon vine straw fiber modified asphalt, and the optimal dosage of groundnut seedling straw fibers was determined; finally, through Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy tests, the chemical components of ground melon vine straw fiber modified asphalt were clarified, and the chemical components of ground melon vine straw fiber modified asphalt were revealed to be the most important. The toughening mechanism of ground melon vine straw fiber modified asphalt was revealed. The results showed that the chemical alkali treatment method was the best preparation process for groundnut straw fiber, and the process flow was to use NaOH solution with a mass fraction of 3 % to treat the ground melon vine straw fiber for 50 min at a temperature of 60 °C; compared with the matrix asphalt, the needle penetration and elongation of the ground melon vine straw fiber modified asphalt decreased with the increase of the blending amount, and the softening point, the equivalent softening point, and the temperature sensitivity of the asphalt increased. Sensitivity enhancement, softening point difference in line with the specification requirements, but the ductility in the low dosage improved; with the increase in the dosage of ground melon vine straw fiber, ground melon vine straw fiber modified asphalt rutting factor, creep modulus, 0.4 %–1 % dosage of the creep rate and creep recovery rate increased, while 1.3 %–1.6 % dosage of the creep rate and the amount of unrecoverable creep flexibility decreased The results show that 0.4 %–1.6 % dosage of melaleuca alternifolia straw fiber modified asphalt high temperature performance and resistance to permanent deformation performance, and 0.4 %–1 % dosage of melaleuca alternifolia straw fiber low temperature performance has also been improved, the overall consideration, to determine the optimal dosage of melaleuca alternifolia straw fiber 1 %; melaleuca alternifolia straw fibers (NaOH) and the asphalt combined with the production of new functional groups, and melaleuca alternifolia straw fibers with each other. Lap cross to form a fiber skeleton grid structure, can play a role in the entire material to transfer stress and crack resistance, asphalt to play the role of enhanced toughening effect.

Rheological and Aging Properties of Nano-Clay/SBS Composite-Modified Asphalt.

Nano-organic montmorillonite (OMMT) not only inhibits the harmful asphalt fume generation during the production and construction processes of asphalt mixtures but also effectively improves the performance of asphalt pavements. In order to prepare asphalt materials with smoke suppression effects and good road performance, this study selects nano-OMMT and SBS-modified asphalt for composite modification of asphalt mixtures and systematically investigates its road performance. Through the temperature sweep test, the frequency sweep test, the multiple stress creep recovery (MSCR) test, the bending beam rheometer (BBR) test, and the atomic force microscope (AFM) test, the high-temperature rheological properties, low-temperature rheological properties, high-temperature properties and aging resistance of the modified asphalt are studied. The research findings indicate that OMMT can effectively reduce the sensitivity of modified asphalt to load stress and improve its high-temperature rheological properties. SBS-modified asphalt shows increased creep stiffness and a decreased creep rate after OMMT modification, resulting in reduced flexibility and decreased low-temperature crack resistance. After short-term and long-term aging, the complex modulus aging index of OMMT/SBS composite-modified asphalt is lower than that of SBS-modified asphalt, and the phase angle aging index is higher than that of SBS-modified asphalt, demonstrating that OMMT enhances the aging resistance of SBS-modified asphalt. OMMT inhibits oxidation reactions in the asphalt matrix, reducing the formation of C=O and S=O bonds, thereby slowing down the aging process of modified asphalt and improving its aging resistance.

MDI-PTMG-based TPU modified asphalt: Preparation, rheological properties and molecular dynamics simulation

Thermoplastic polyurethane elastomer (TPU) modified asphalt was prepared by a two-step process using MDI and PTMG. The improvement effects of different TPU content on high-and low-temperature rheological properties and thermal stability of asphalt were studied through experimental tests. The results showed that TPU could enhance the high-temperature properties of asphalt obviously. The improvement effect was more significant with the increase of TPU content. At the same time, glass transition temperature (Tg) of asphalt decreased with the increase of TPU content, indicating that TPU could improve the low-temperature performance of asphalt. These experimental results were further verified by the Molecular dynamics (MD) simulation results. Materials Studio 8.0 was used to establish the molecular models of asphalt, TPU and TPU modified asphalt. The effects of TPU content on mechanical modulus and Tg of asphalt were studied by MD simulation. The results revealed that TPU formed a close structure with asphalt to improve the structural stability of asphalt. And the free volume fraction of the modified asphalt decreased with the increase of TPU content. Thus, the high-temperature properties of asphalt were improved. The calculated Tg and moduli obtained from MD simulation accorded well with the experimental results from DSC and DSR, respectively. This study suggests a novel way to provide guidance for the development of TPU modified asphalt.

Influence of preparation parameters on rheological properties and relation analysis of waste rubber modified bitumen mastic

Waste rubber modified bitumen has gained significant attention as a sustainable and innovative material in the field of pavement engineering. This study aims to evaluate the performance of rubber modified bitumen mastic by considering its rheological properties, specifically focusing on preparation parameters, i.e., rubber content, mesh number, and filler to bitumen ratio. From the experimental results, the rheological properties of rubber modified bitumen mastic were significantly influenced by preparation parameters. Increasing the rubber powder content in bitumen mastic results in higher viscosity. Increasing the rubber content improves high-temperature rutting resistance to a certain extent, however, excessive rubber powder content would result in weakened high-temperature performance improvement. The rutting factor decreases gradually with an increase in the rubber mesh number. A ratio of filler to bitumen of 0.95 exhibits the best resistance to rutting at high temperatures. Higher rubber content and larger mesh number correspond to stronger low-temperature crack resistance in bitumen mastic. As the ratio of filler to bitumen increases, the low-temperature deformation capacity gradually decreases, resulting in weaker low-temperature crack resistance. Based on the grey relation analysis, the ratio of filler to bitumen has the greatest impact on the high and low-temperature rheological properties of bitumen mastic, followed by the rubber content. The rubber mesh number has a relatively lower impact. It is crucial to control the ratio of filler to bitumen to avoid excessive values. When possible, a higher rubber powder content should be used while meeting process requirements. These findings provide valuable insights into the design and optimization of rubber modified bitumen mastic, which can contribute to the development of sustainable and high-performance bitumen mixtures, promoting the use of recycled rubber in pavement engineering.

Effect of waste cooking oil on the performance of EVA modified asphalt and its mechanism analysis

The balance between the low and high temperature performance of asphalt materials is important to avoid either rutting deformation or low temperature cracking resistance of asphalt pavement. This is beneficial for improving the asphalt pavement comprehensive performance. Considering the excellent high temperature performance of Ethylene–vinyl acetate (EVA) modified asphalt, this study first modified it with Waste Biological Oil (WBO) to prepare WBO/EVA composite modified asphalt (WEMA) with different dosages. Then the samples were evaluated by the traditional physical properties, low and high temperature rheological properties. Finally, the micro mechanism of WBO on EVA modified asphalt were explored by gel permeation chromatography (GPC) test and atomic force microscope (AFM) experiments. The experimental results reveal that WBO has a softening effect on EVA modified asphalt, reducing its stiffness and improving its stretching performance and flowability. In addition, WBO can reduce the high-temperature deformation resistance of EMA modified asphalt, but it significantly enhances the low-temperature property of EVA modified asphalt. When the WBO content ranges from 1.5 to 2.5%, the high-temperature performance of WEMA is inferior to that of EVA-modified asphalt, however, its low-temperature performance is significantly better than that of EVA-modified asphalt. Importantly, within this WBO content range, the comprehensive performance of WEMA is superior to that of pure asphalt. Mechanism investigation showed that WBO reduces the content of macromolecular micelles and average molecular weight in EVA modified asphalt, and it also diluts the asphaltene components in the asphalt system, resulting in a slight weakening of the performance of WEMA at high temperatures and a significant performance enhancement at low temperatures. Ultimately, the utilization of WBO/EVA composite modified asphalt has a better comprehensive performance.

The influence mechanism of bitumen components on its macroscopic and microscopic properties: Analysis based on polyphosphoric acid modification

In order to investigate the impact of bitumen components on its overall properties, various modified bitumen with 1.0 %PPA or 2.0 %SBS/SBR + 0.6 %PPA were prepared. The influence of PPA dosage on bitumen’s physical properties were evaluated, and the macroscopic and microscopic properties of each bitumen sample were characterized by DSR, BBR and atomic force microscopy observation. The components of bitumen were separated through SARA test, and the infrared spectroscopy of asphaltenes was further analyzed. The findings suggest a significant impact on bitumen with PPA incorporation, the elastic recovery properties of bitumen at high temperatures were enhanced due to a more stable colloidal structure was formed by the dispersion and interaction of macromolecular asphaltenes. However, the low-temperature rheological properties of bitumen were impaired by reason of a relatively reduced flowable lightweight component. Specifically, the large asphaltenes clusters were dispersed cause PPA reacted with the –OH bonds of alcohols in bitumen by phosphorylation. By modeling the correlation between bitumen component contents and its microscopic surface parameters, the asphaltenes decomposition was demonstrated to be an important factor on the microscopic morphology, which was also related to the content of saturates and aromatics. Thus, a method for deconstructing bitumen from a compositional perspective is proposed.

Tuning high- and low-temperature rheological properties of warm-mixing asphalt composites by functionalized waxes

Traditional asphalt road construction utilizes hot-mixing asphalt mixtures. High temperatures not only accelerate the aging of asphalt, but also produce large amounts of toxic and greenhouse gases. To alleviate these problems, wax-based warm-mixing agents are applied, and asphalt pavement construction temperatures can be efficiently lowered, resulting in lower energy and gas emissions. To systematically evaluate the effects of composition and structure of warm-mixing agents on rheological properties of asphalt at high and low temperatures, a series of functionalized waxes (i.e., oxygen-containing groups, amide groups, and long-chain aliphatic hydrocarbons) were designed in this work, followed by a melt-mixing process with asphalt. The findings demonstrated that warm-mixing agents with long-chain aliphatic hydrocarbons could significantly improve asphalt composites’ rheological properties at high temperatures, such as good viscosity-reducing effect and superior rutting resistance or permanent deformation resistance; warm-mixing agents with oxygen groups were able to improve the asphalt composites’ resistance to low-temperature cracking; amide group-containing warm-mixing agents could improve the surface roughness of asphalt composites. This work provides a practical guide for the selection of functionalized warm-mixing agents for asphalt pavement under multiple environmental factors.

Low-temperature rheological properties and viscosity equation of Al/HTPB suspension system

The rheological behavior of propellant slurries is crucial for ensuring the feasibility of the 3D printing process, controlling print quality, regulating performance, and simulating predictions. However, there have been relatively few prior studies on the rheological properties of composite solid propellant slurries at low temperatures, which hinders the application of 3D printing propellant technology under extreme temperature conditions. In addition, the use of 3D printing technology to manufacture propellants at low temperatures is advantageous for improving safety. This paper investigates the rheological properties of monodisperse systems with aluminum powder as a solid filler and end-hydroxy polybutadiene (HTPB) as the dispersed phase at low temperatures (−15∼10 °C). It explores the effects of solid content, temperature, and particle size on their rheological properties. Results show that the viscosity of the system in the range of −15∼10 °C increases exponentially with the decrease in temperature, and the viscosity at −15 °C increases by 616.90 % compared with that at 10 °C when the volume fraction (φ) of Al-1 is 35.8 %; the larger size of the particles the larger the viscosity is when the temperature and φ are the same, which is interpretes in terms of interfacial properties between the systems. The low-temperature correction factor is introduced into the Einstein-Roscoe equation to obtain the modified viscosity-volume fraction equation, and the correction factor is 0.0173, as evidenced by its excellent agreement with the experimental data.

Investigation of rheological properties of asphalt modified with low-temperature microencapsulated eutectic phase change materials

The effects of microencapsulated eutectic phase change materials (MEPCMs) on the viscosity-temperature relationship, viscoelasticity, creep recovery, and low-temperature properties of base asphalt and SBS asphalt were investigated using dynamic shear rheometer (DSR) and bending beam rheometer (BBR). The results revealed that the incorporation of microcapsules led to a reduction in the complex modulus and viscosity of the asphalt. Notably, at a concentration of 13 wt%, microcapsules disrupted the linear viscoelastic behavior of the asphalt and compromised its phase uniformity. However, the addition of microcapsules improved the low-temperature rheological properties of the asphalt. Specifically, the S and m-values of the asphalt decreased and increased, respectively, with increasing microcapsule content. Moreover, SBS asphalt exhibited less susceptibility to the effects of microcapsules compared to base asphalt, owing to its superior performance across a wide range of temperatures. This characteristic renders SBS asphalt more compatible with MPCMs for practical applications.

Evaluation of benzaldehyd and dioctyl phthalate modified direct coal liquefaction residue asphalt binder based on rheology and microscopic mechanisms

This study intends to investigate the influence of benzaldehyde and dioctyl phthalate (DOP) on the rheological properties and microstructure of direct coal liquefaction residue (DCLR) modified asphalt binder. The high and low temperature rheological properties and fatigue properties were obtained by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) tests. The scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) tests were conducted to evaluate the mechanism of property improvement in the DCLR modified asphalt binder. The results showed that the addition of DCLR increased the complex shear modulus G*, rutting factor G*/sin δ and fatigue life Nf of base asphalt binder, significantly improving the high temperature deformation resistance and fatigue resistance of base asphalt binder. This was attributed to the hardening effect resulting from the addition of DCLR, which enhanced the elastic properties, weakened the viscous properties and fluidity of asphalt binder. Additionally, the use of benzaldehyde and DOP reduced the creep stiffness S and lower continuous grading temperature Tc of DCLR modified asphalt binder, which compensated for the shortcomings of low temperature rheological properties of asphalt binder. The SEM images indicated that benzaldehyde and DOP significantly increased the compatibility of DCLR with the base asphalt binder. The FTIR tests showed that the addition of benzaldehyde and DOP introduced the aldehyde and ester groups, which were interacted with more polar functional groups in the asphalt to reduce the resistance to movement between the heavy components in the DCLR modified asphalt binder, which promoted the flow of asphalt and the dispersion of DCLR, and as a result, the benzaldehyde and DOP modified DCLR asphalt binder exhibited satisfied rheological properties.

Nano-Scale and Macro-Scale Characterizations of the Effects of Recycled Plastics on Asphalt Binder Properties

This paper summarizes the results of one of the first comprehensive laboratory studies that was conducted to evaluate the effects of adding different contents of recycled polyethylene terephthalate (rPETE) as a modifier to an asphalt binder on the rheological and mechanical properties of the modified binder as well as on the agglomeration behavior between the rPETE and asphalt binder at a multiscale level. The high-temperature and low-temperature performances of the modified binder were investigated at the macro-scale and compared with those of the unmodified binder using dynamic shear rheometer (DSR) and bending-beam rheometer (BBR) rheological tests, as well as asphalt binder cracking device (ABCD) testing. The nano-scale evaluation of the binder properties, including the surface roughness, bonding energy, and reduced modulus, was accomplished using atomic force microscopy (AFM). The results indicated that the addition of rPETE enhanced the high- and intermediate-temperature rheological properties of the modified PG 64-22 binder. The low-temperature rheological properties and resistance to cracking decreased slightly with increasing rPETE content in the asphalt binder. However, this reduction was not remarkable when adding 4%, 8%, and 10% rPETE contents. The asphalt binder modified with 4% rPETE had a low-temperature grade of −22, similar to that of the unmodified binder, indicating that 4% rPETE can be added to the binder to improve its high- and intermediate-temperature properties without reducing its resistance to low-temperature damage. The AFM tapping-mode results indicated that the inclusion of rPETE in the asphalt binder improved the stiffness properties of the modified binder as compared with those of the control asphalt binder. In addition, the rPETE-modified binders showed rougher surfaces than the control binder. The addition of rPETE to the binder increased the values of the reduced modulus and bonding energy compared with those of the control binder.

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.

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.

Investigation of Phenolic Resin-Modified Asphalt and Its Mixtures.

This study comprehensively examines the influence of phenol-formaldehyde resin (PF) on the performance of base asphalt and its mixtures for road applications, emphasizing its innovative use in enhancing pavement quality. Optimal PF content was determined through the evaluation of standard indicators and rotational viscosity. In-depth analyses of PF-modified asphalt's high- and low-temperature rheological properties and viscoelastic behavior were conducted using dynamic shear rheometers and bending beam rheometers. Aging resistance was assessed through short-term aging and performance grade (PG) grading. Moreover, Marshall and water stability tests were performed on PF-modified asphalt mixtures. Findings indicate that the uniform dispersion of PF particles effectively inhibits asphalt flow at high temperatures, impedes oxygen penetration, and delays the transition from elasticity to viscosity. These unique properties enhance the high-temperature stability, rutting resistance, and aging resistance of PF-modified asphalt. However, under extremely low temperatures, PF's brittleness may impact asphalt flexibility. Nonetheless, the structural advantages of PF-modified asphalt, such as improved mixture density and stability, contribute to enhanced high-temperature performance, water stability, adhesion, and freeze-thaw cycle stability. This research demonstrates the feasibility and effectiveness of using PF to enhance the overall performance of base asphalt and asphalt mixtures for road construction.

Study on the anti-aging properties of organic attapulgite (OATT) and polyurethane (PU) composite-modified asphalt

Study on the anti-aging properties of organic attapulgite (OATT) and polyurethane (PU) composite-modified asphalt

Performance evaluation of styreneic methyl copolymer regenerated SBS-modified asphalt and its mixture with high content RAP

The aging degree of reclaimed asphalt pavement (RAP) is complex and diverse, and the current utilization rate of RAP is far from meeting the needs of green cycle development. To explore the effect of Styreneic Methyl Copolymer (SMC) rejuvenator of aging asphalt and the performance of SMC regenerated asphalt mixture containing 50% and 60% RAP, this study used SMC rejuvenator to regenerate SBS-modified asphalt with different aging degrees. The high and low-temperature rheological properties of regenerated asphalt were evaluated by temperature sweep test, multi stress creep recovery test, and bending beam rheometer test. Then, the recommended content of the SMC rejuvenator was obtained by using Matlab to establish the corresponding model. Finally, the road performance of the regenerated mixture with high-content RAP was verified. The test results showed that the recommended content range of the SMC rejuvenator for the aging asphalt with PAV (Pressurized Aging Vessel) 0 h, PAV5h, PAV10h, PAV15h, PAV20h were 1.56∼2.31%, 3.03∼3.36%, 4.269∼4.48%, 5.23∼5.66%, 5.95∼6.91%, respectively. The road performance of the SMC regenerated asphalt mixture with 50% and 60% RAP content met the specification requirements. SMC rejuvenator had no significant negative impact on high-temperature performance, significantly improving low-temperature cracking resistance. SMC regenerator had a positive significance in improving regeneration efficiency.

Improving anti-aging performance of terminal blend rubberized bitumen by using graft activated crumb rubber

Abstract The appearance of terminal blend rubberized bitumen (TB) has improved a series of defects of traditional rubber bitumen, such as high viscosity, poor storage stability. Therefore, its wide application prospect is self-evident. However, different degrees of thermal-oxidative aging problem still exist in the process from production to use of TB, which seriously affects the service life of pavement. To improve the anti-aging performance of TB, grafting activated crumb rubber (GACR) was obtained by using acrylamide, and then compounded with TB. Firstly, TB was prepared in the self-developed nitrogen protection device. Secondly, GACR modified bitumen (GACR-MB), TB/CR composite modified bitumen (TB/CR) and TB/GACR composite modified bitumen (TB/GACR) were developed in the atmospheric environment. Finally, the performance of four kinds of crumb rubber modified bitumens before and after aging was compared and analyzed by testing high and low temperature rheological properties. The results show that GACR slowed down the formation rate and aggregation degree of asphaltenes and other macromolecular substances, and TB/GACR showed excellent aging resistance.

Study on the Rheological Performance and Microscopic Mechanism of PPA/SBS/SBR Composite-Modified Asphalt Cold Replenishment Liquid

To prepare high-performance asphalt cold replacement liquids, a composite modification preparation process was used to synthesize a styrene–butadiene–styrene (SBS) block copolymer, styrene–butadiene–rubber (SBR) copolymer, and polyphosphate acid (PPA), erucamide/diesel/acrylic ester as surfactants/diluents/reinforcing agent respectively. These six were blended to prepare an asphalt cold replenishment liquid (ACRL), and its modification effect on base asphalt was studied using base asphalt as the control group. A comparative study was conducted on the high- and low-temperature rheological properties and microstructure. The modification mechanisms of high-temperature asphalt cold replenishment liquid (H-ACRL) and low-temperature asphalt cold replenishment liquid (L-ACRL) were studied through dynamic shear rheometry, bending beam rheometry, Fourier-transform infrared spectroscopy, fluorescence microscopy, and atomic force microscopy. The results showed that the optimal dosages of PPA/SBS/SBR in H-ACRL and L-ACRL were (1.2%/5%/3%) and (0.9%/4%/4%), respectively. Within the optimal dosage range, the particles in the cold replenishment fluid were uniformly dispersed in the asphalt to form a dense and continuous network. No new functional groups were generated during the preparation of H-ACRL and L-ACRL, showing that the modifiers (surfactants/diluents/reinforcing agent) were only physically blended with the asphalt.

Preparation and properties of a newly developed devulcanized and pyrolytic crumb rubber modified asphalt

Purpose The purpose of this article is to determine the parameters of the preparation process for devulcanized and pyrolytic crumb rubber modified asphalt (DCRMA) and then study the rheological and microscopic properties of DCRMA through experiments.Design/methodology/approach In this study, a new preparation process for DCRMA was developed, then the penetration, softening point and viscosity tests were employed to determine the parameters of the preparation process. The crumb rubber (CR) solubility, Fluorescence microscopy (FM), Fourier Transform Infrared (FTIR) spectroscopy and thermogravimetric analysis tests were conducted to verify the devulcanized and pyrolytic effectiveness of the preparation process. Furthermore, dynamic shear rheometer and bending beam rheometer were used to characterize the high and low-temperature rheological properties of DCRMA.Findings The results showed that the penetration balanced the CR degradation and the virgin asphalt aging well and thus could be used as a main parameters control indicator. The CR solubility, FM and FTIR tests proved that the CR has been fully devulcanized and pyrolytic via the preparation process. The DCRMA exhibited better low-temperature and fatigue performance and lower rutting performance than the conventional crumb rubber modified asphalt (CRMA) with the same CR content. Finally, the time–temperature superposition principle could be employed for all binders in this study.Originality/value A new preparation process for DCRMA was developed.