Dynamic Shear Rheological Test Research Articles

Preparation of Wax-Based Warm Mixture Additives from Waste Polypropylene (PP) Plastic and Their Effects on the Properties of Modified Asphalt

The production of high-performance, low-cost warm mix additives (WMa) for matrix asphalt remains a challenge. The pyrolysis method was employed to prepare wax-based WMa using waste polypropylene plastic (WPP) as the raw material in this study. Penetration, softening point, ductility, rotational viscosity, and dynamic shear rheological tests were performed to determine the physical and rheological properties of the modified asphalt. The adhesion properties were characterized using the surface free energy (SFE) method. We proved that the pyrolysis temperature and pressure play a synergistic role in the production of wax-based WMa from WPPs. The product prepared at 380 °C and 1.0 MPa (380-1.0) can improve the penetration of matrix asphalt by 61% and reduce the viscosity (135 °C) of matrix asphalt by 48.6%. Furthermore, the modified asphalt shows favorable elasticity, rutting resistance, and adhesion properties; thus, it serves as a promising WMa for asphalt binders.

Effect of fiber characteristic parameters on the high and low temperature rheological properties of basalt fiber modified asphalt mortar

Fiber has an important influence on the performance of asphalt materials. However, the effect of fiber characteristic parameters (length, type, etc.) on the function of asphalt mortar is still lack of understanding. Therefore, a systematical experimental plan was conducted to evaluate the effects of the selected parameters of filler-binder ratio, fiber type, fiber content and fiber length on the rheological properties of asphalt mortar, including five filler-binder ratios (0.6, 0.8, 1.0, 1.2 and 1.4), four fiber types (three chopped basalt fibers with different coating agents named A, B and C and one flocculent basalt fiber), five fiber contents (1%, 2%, 3%, 4% and 5%) and three fiber lengths (6 mm, 9 mm, 15 mm). Then, Dynamic Shear Rheological (DSR) tests and Bending Beam Rheological (BBR) tests were employed to evaluate the rheological behavior of each asphalt mortar. The corresponding reinforcing mechanism was subsequently analyzed by Environmental Scanning Electron Microscope (ESEM) test. The results show that basalt fiber can obviously enhance the high-temperature rheological properties of asphalt mortars, while strengthen the stress dissipating ability at low temperatures to some extent. Besides, the fiber type, fiber content and fiber length all impact the rheological properties of asphalt mortars. The asphalt mortars with type A basalt fiber present the superior rheological performance at both high and low temperature, with the optimum fiber content of 2% and fiber length of 9 mm, respectively. The test results of ESEM reveals that basalt fiber shows spatial distribution in asphalt mortar, presenting the function of stabilization and reinforcement.

Recycling Non-Metallic Powder of Waste Printed Circuit Boards to Improve the Performance of Asphalt Material.

Non-metallic fractions (NMFs) from waste printed circuit boards (PCBs) are mostly composed of cured resin and fiber. In this study, NMF material from a PCB was ground into powder and added into matrix asphalt to produce PCB-NMF-modified asphalt. To improve the compatibility of PCB-NMF and asphalt, a compatibilizer consisting of tung oil and glycerol was also developed. The optimum compatibilizer content was determined to be 8% by weight of the PCB-NMF through a series of laboratory tests, including the softening point, penetration, ductility, and softening point difference (SPD). The micro-mechanism of NMF powder-modified asphalt was analyzed through Fourier transform infrared spectroscopy (FTIR) and a scanning electron microscope test (SEM). The performances of PCB-NMF-modified asphalt were evaluated by the dynamic shear rheology (DSR) test and the low-temperature bending beam rheometer (BBR) test. The optimum compatibilizer content was 8% by weight of the NMF powder and the optimum content of NMF powder was determined to be 30% by weight of the asphalt based on a comprehensive evaluation. The results show that PCB-NMF can significantly improve stiffness, rutting resistance, high-temperature stability, and temperature sensitivity of asphalt material at an appropriate content. The BBR tests revealed that PCB-NMF slightly weakened the cracking resistance of asphalt at low temperatures. The SEM test showed that the addition of a compatibilizer can increase the compatibility by making the NMF powder evenly dispersed. The FTIR test results implied that a chemical reaction may not have happened between PCB-NMF, compatibilizer, and the matrix asphalt. Overall, it is a promising and sustainable way to utilize PCB-NMF as a modifier for asphalt material and reduce electronic waste treatment at a low cost.

Microscale Property Evaluation of the Interface between Cement Emulsified Asphalt and Aged Asphalt in Emulsified Asphalt Cold Recycled Mixture

To study the microscale properties of the interface between cement emulsified asphalt and aged asphalt in the emulsified asphalt cold recycled mixture, the PeakForce quantitative nano mechanics (PF-QNM) technology of atomic force microscope (AFM) and dynamic shear rheological (DSR) test were used. The results showed that at the microscale, the cement products were spot-like distribution in the surface morphology of the composite system consisting of cement emulsified asphalt and aged asphalt. The approximate interface area could be distinguished by the distribution of the cement products. The gradient of the microscale mechanical properties between cement emulsified asphalt and aged asphalt could quantify the interface thickness. When the penetration of aged asphalt was less than 20 (0.1 mm) and the cement content was 1.0%–2.0%, the mechanical properties of interface were relatively close, and the theory of black aggregate was basically applicable. At the macroscale, the rheological property of the composite system had a good correlation with the microscale modulus of the interface, and a quantitative model of the correlation was proposed. When the penetration of aged asphalt was less than 30 (0.1 mm), the fatigue property of the composite system was relatively close under the same cement content, and the fatigue resistance of the composite system could be improved to a large extent by decreasing the cement content appropriately. Finally, to obtain a more general conclusion, it is necessary to choose a variety of emulsified asphalt and carry out a comparative analysis of different emulsified asphalt content.

Establishment of a Quantitative Time Conversion Relationship Between Laboratory Accelerated Weathering Aging and Outdoor Natural Aging of the High-Content Polymer Modified Asphalt Applied in Porous Asphalt Pavement: From Theory to Experiment

The purpose of this study was to determine the quantitative time conversion relationship between indoor accelerated weathering aging (AWA) and outdoor natural aging of the high-content polymer modified asphalt (HCPMA) applied in porous asphalt pavement from both theoretical and experimental aspects. Firstly, the calculated aging acceleration rate of the AWA test was determined based on orthogonal analysis and chemical reaction kinetics. The indoor AWA test (0–12 days) and outdoor natural aging (0–12 months) were then performed on HCPMA, and the dynamic shear rheology test and multiple stress creep recovery test were conducted to investigate the rheological properties of HCPMA. Furthermore, the measured aging acceleration rate of the AWA test was determined according to rheological index comparison and then compared with the calculated aging acceleration rate to obtain the ultimate time conversion relationship between indoor and outdoor aging. Results show that it is practical to simulate the natural aging by using the AWA test. HCPMA exhibits similar changes in macroscopic rheological properties in indoor AWA and outdoor natural aging. According to the comparison of rheological indexes, the measured aging acceleration rate of HCPMA under the harshest aging condition is 57.5–120, which is basically consistent with the calculated aging acceleration rate (66) by the chemical reaction kinetics. This further demonstrates the feasibility of this study for determining the indoor-outdoor aging time conversion relationship from theoretical and experimental aspects.

Research on High-Temperature Rheological Properties of Emulsified Asphalt Mastics and Their Influencing Factors

The high-temperature rheological properties of emulsified asphalt mastics have a significant impact on the service performance of cold recycled mixtures with asphalt emulsions. In this paper, a dynamic shear rheological (DSR) test and a multiple stress creep recovery (MSCR) test are carried out to analyze the influence of tunneling coal gangue powder (TCGP), portland cement (PC), limestone powder (LP), and four kinds of filler binder ratio (F/B) on the high-temperature rheological properties of emulsified asphalt mastics before and after rolling thin film oven test (RTFOT) ageing. Based on the principle of time–temperature equivalence and a viscoelasticity material model, the main curve of emulsified asphalt mastics under frequency scanning test is established, and the rheological properties of emulsified asphalt mastics in a wide frequency domain are analyzed. Finally, the grey entropy theory is used to quantitatively analyze the correlation between different high temperature performance evaluation indices of emulsified asphalt mastics. The results show that the RTFOT ageing process can significantly enhance the high temperature deformation resistance of emulsified asphalt residue and its mastics. The rutting factor (G*/sin δ) of emulsified asphalt mastics increases exponentially with the increase of F/B, while the phase angle is less affected. TCGP mastics and PC mastics have better high temperature performances than those of LP mastics. The most suitable range of F/B is 0.9~1.2 when TCGP is used as the filler, and 1.2~1.5 when PC or LP is used as the filler. Grey entropy correlation analysis shows that there is a good correlation between the two evaluation systems of the DSR test and the MSCR test, and both can evaluate the high-temperature performance of emulsified asphalt mastics.

A sustainable high-viscosity modified asphalt modified with multiple anti-aging agents: Micro-chemical analysis and macro-rheological characterization

This study aimed to use aging inhibition technology to actively improve the environmental aging resistance, thus achieving the sustainable and long-life application of high-viscosity modified asphalt (HVMA). The sustainable HVMAs with different anti-aging agents was prepared, and the long-term environmental aging effect, including solar radiation, heat, and moisture, was simulated using the accelerated environmental aging tester. Then, the chemical and molecular composition of sustainable HVMAs were investigated using Fourier transform infrared spectroscopy test, X-ray photoelectron spectroscopy test, and gel permeation chromatography test. Afterwards, the nano-indentation test was used to study the nanomechanical property of sustainable HVMAs. Finally, the dynamic shear rheology test and linear amplitude sweep test were applied to evaluate the aging resistance, crack resistance, and fatigue resistance of sustainable HVMAs. The results show that environmental aging leads to the rapid oxidation of asphalt molecules and substantial degradation of polymer molecules in HVMA, as evidenced by the transformation of carbon elements from CC/CH bonds to CO/CO bonds and sulfur elements from CSC bonds to SO/OSO bonds. A single anti-aging agent has a little aging inhibition effect, while the compounding of multiple anti-aging agents has a synergistic anti-aging enhancement effect. The combination of UV absorbers and UV blocking agents can absorb/reflect some of the UV rays and delay the UV aging process. However, they cannot effectively prevent the binding of UV-excited reactive radicals with oxygen. In contrast, incorporating antioxidants can allow hydrogen atoms to combine with UV-excited reactive radicals and prevent further oxidation of asphalt molecules. The compound incorporation of UV absorbers, UV blocking agents, and antioxidants can improve the rheology property, crack resistance, and fatigue resistance of aged HVMA, thus effectively promoting the sustainable and long-life application of HVMA.

Composition and Evaluation on Road Performance of SBS/PTW High-Viscosity-Modified Asphalt and Its Mixtures for Ultrathin Overlays

As a highway pavement maintenance technology, the road performance of the ultra-thin overlay depends heavily on the performance of asphalt cement. For the preparation of high-performance-modified asphalt suitable for ultrathin overlay, the reactive blending technology was used based on SBS modified asphalt and combined with a penetration test, softening point test, ductility test, dynamic viscosity test, and viscous toughness test to study the optimal blending ratio of high-viscosity modified asphalt. Further, the rolling thin-film oven test (RTFOT), dynamic shear rheological (DSR) test, and Brookfield viscosity test are used to evaluate the technical properties of SBS/PTW modified asphalt under the best mixing ratio. Finally, the SMA-13 asphalt mixture was prepared with SBS/PTW high-viscosity modified asphalt and evaluated through a rutting test, low-temperature bending test, immersion Marshall test, freeze-thaw splitting test, structural depth test (TD), and British pendulum number (BPN) test. These results showed that the best blending mass ratio of high-viscosity modified asphalt is 6% SBS + 4% solubilizer + 0.2% PTW + 0.2% nano-ZnO. All technical property indexes of the prepared SBS/PTW high-viscosity modified asphalt meet the requirements of an ultra-thin overlay binder. The dynamic viscosity at 60°C reaches 64204 Pa·s, and the viscosity and toughness are 25.4 N·m and 20.9 N·m, respectively. SBS/PTW high-viscosity modified asphalt under dynamic shear rheology (DSR) test is classified as PG88 at high temperature. The rutting factor changes the smallest before and after aging, and it has excellent anti-aging performance. Furthermore, the asphalt mixture prepared by SBS/PTW high-viscosity modified asphalt has excellent high and low-temperature performance, water stability, and skid resistance performance. All properties meet the requirements of the ultra-thin overlay. This study demonstrated that the SBS/PTW high-viscosity modified asphalt possessed high viscosity properties, which can be used in the ultra-thin overlay and other highly demanding working environments.

Evaluation method of storage stability of SBS modified bitumen based on dynamic rheological properties

In order to better evaluate the storage stability of Styrene-Butadiene-Styrene Block copolymer (SBS) modified bitumen at high temperature, this paper analyzed the law of Dynamic shear rheological (DSR) test results of SBS modified bitumen after high-temperature storage and proposed DSR segregation parameters and DSR segregation index of SBS modified bitumen based on DSR test. Many kinds of SBS modified bitumen were prepared, and the application of DSR segregation index to evaluate the high-temperature storage stability of SBS modified bitumen was carried out. The main conclusions are: Take the DSR test results of SBS modified bitumen stored at high temperature but continuously stirred without segregation as the reference value, under the same storage temperature and time, the percentage of the difference of Complex modulus (G*) or Phase angle (δ) or Rutting factor (G*/sin δ) between the upper 1/3 and the bottom 1/3 of SBS modified bitumen to the reference value shows a linear relationship at different scanning temperatures. The closer the slope of DSR segregation parameters with temperature is to 0, the better the storage stability of the bitumen is. DSR segregation index takes DSR segregation parameter as parameters and is associated with the difference of segregation softening point. When the DSR segregation index is greater than 0, the storage stability of SBS modified bitumen can meet the requirements of the current standard. DSR segregation index is not bound to the type of bitumen, it is speculated that it is closely related to the compatibility between bitumen and SBS modifier. All factors affecting the storage stability of SBS modified bitumen affect the DSR segregation index. DSR segregation index has high stability in the evaluation of high-temperature storage stability of SBS modified bitumen and can be used as an auxiliary evaluation index of 48 h segregation softening point difference.

Study on pavement performance of cotton straw cellulose modified asphalt

To improve the pavement performance of heavy traffic asphalt pavement, two modifiers, cotton straw powder and cotton straw cellulose, were added to matrix asphalt. Through the tenacity test, dynamic shear rheological test, multi-stress creep recovery test and bending beam rheological test of asphalt, the tenacity, high temperature properties, viscoelastic properties and low temperature properties of three kinds of asphalt, including matrix asphalt, cotton straw powder modified asphalt and cotton straw cellulose modified asphalt, were evaluated. Scanning electron microscopy and synchronous thermal analyzer were used to analyze the microstructure and thermal stability of modified asphalt. The results show that both cotton stalk powder and cotton stalk cellulose can effectively improve the tenacity, temperature sensitivity and rheological properties of asphalt. The comprehensive improvement effect of 1% cotton straw cellulose is the best, but its low temperature performance has not been improved significantly. Cotton straw cellulose and asphalt form a more stable system, thereby improving the stability of asphalt. The increase of asphaltene content and the decrease of aromatic content are due to the good oil absorption of cotton straw cellulose, and the high temperature performance of asphalt is improved.

Steady and dynamic shear rheology of Indian Jujube (Ziziphus mauritiana Lam.) fruit pulp with physiochemical, textural and thermal properties of the fruit

Indian jujube (Ziziphus mauritiana Lam.) is a globally underutilized fruit and is well-known for being a good source of total phenolics and a rich source of ascorbic acid with essential minerals such as calcium, phosphorus and iron. A rheometer was used to investigate the rheological characterization of Indian jujube pulp. It was found that Indian jujube pulp exhibit a shear thinning behaviour as viscosity (η) and shear stress (σ) of pulp significantly (p < 0.05) decreased as the shear rate (γ̇̇) increased. Pulp's behaviour was characterized efficiently by correlating Power-law, Carreau-Yasuda, and Cross models with flow curve. The Cross model was found more efficient (R2:0.99775) than the Power-law (R2:0.85995) and Carreau-Yasuda model (R2:0.97291). Dynamic shear rheology test of the Indian jujube pulp presented weak gel behaviour as storage modulus (G') surpassed loss modulus (G") value. The frequency dependency of both the storage G′ and loss G′′ moduli was evaluated using a power Law model with a determination coefficient (R2) greater than 0.9. The tan(δ) values (0.020 to 0.535) suggested that the Indian jujube pulp is elastic in nature. Textural properties of Indian jujube fruit like hardness, percentage deformation at the hardness and peak stress of Indian jujube fruit were 32.76 ± 5.00 N, 7.15 ± 1.06% and 17780.80 ± 3185.47 N/m2. DSC curve showed glass transition phase of unprocessed Indian jujube fruit flesh at (98.29°C), and specific heat (Delta Cp) was found 193.96 J/g. The findings of this study will aid in the development of handling and processing machinery for the commercial manufacture of Indian jujube pulp.

High-Temperature Property Evaluation and Index Research of Modified Asphalt before and After Aging

In order to better evaluate the composite modified asphalt of composite modified asphalt, this study through dynamic shear rheological (DSR) test, the three kinds of polymer modified asphalt before and after ageing: the compound modified asphalt (CCR), rubber powder modified asphalt (CR) and composite modified asphalt of SBS modified asphalt (SBS) analysis, to explore suitable for composite modified asphalt of modified asphalt evaluation index. The results show that: Compared with G*/sinδ, G*/(sinδ)9 has higher accuracy for evaluating the composite modified asphalt of polymer modified asphalt and is more sensitive to changes in phase angle. The critical temperature of anti-rutting factor TG*/sinδ9 is significantly higher than that of TG*/sinδ, especially for composite modified asphalt. This has an important impact on the PG classification in the Superpave asphalt binder specification. G*/sinδ underestimates the high temperature grade of the modified asphalt. The equivalent viscosity measured with η’ = sinδ-4.8628 G*/ω has the best correlation with the anti-rutting factor G*/(sinδ)9, and the highest correlation coefficient is 0.999, which is more suitable as a high-temperature property evaluation index of modified asphalt.

Research on the micro-nano characteristic of basalt fiber and its impact on the performance of relevant asphalt mastic

The surface properties have significant impacts on the performance of fiber composites. To evaluate the effects of fiber modification on the rheological and interface adhesion properties of basalt fiber asphalt mastic (BFAM), basalt fiber (BF) was modified using a silane coupling agent to prepare BFAM. The micro-nano characteristics of BF were evaluated by Scanning electron microscope, Fourier transform infrared spectroscopy, Surface energy test and X-ray energy dispersive spectroscopy. The rheologicalproperties of BFAM were examined by dynamic shear rheological (DSR) test and bending beam rheological (BBR) test. Besides, the pull-out test was employed to assess the interfacial adhesion between fiber and asphalt, the relationship between the rheologicaland adhesion properties was also analyzed. The results showed that modified basalt fiber (MBF) has higher surface energy and roughness than the original fiber. The reaction process on fiber surface slowed down when the modification time exceeded 30 min and the concentration exceeded 2.0%. MBF showed a better enhancement effect on the high / low temperature rheological properties of asphalt mastic than BF. The enhancement of rheological properties is positively correlated with the interface adhesion. The findings provide significant guidance for the application and promotion of fiber asphalt pavements.

Effect of different basalt fibers on the rheological behavior of asphalt mastic

Many research has indicated that fiber content and type have an essential effect on the asphalt mixture performances. However, the impact of fiber properties has not been studied enough. Thus, to evaluate the fiber properties on the rheological behavior of asphalt mastic, this paper adopted four kinds of basalt fibers (three short-cut fibers coated with different infiltration agents and one flocculated basalt fiber, noted as BF-A, BF-B, BF-C, and FBF) and chosen a lignin fiber (noted as LF) as a comparison. First, the hygroscopicity, pH value, and asphalt-adsorption capacity of the five fibers were tested. Then, the rheological behavior of different asphalt mastics was evaluated by viscosity test, Dynamic Shear Rheological (DSR) test, and Bending Beam Rheology (BBR) test. Moreover, microscopic images of the fibers and the asphalt mastics were taken by an Environmental Scanning Electron Microscope (ESEM) to analyze the mechanism of different fiber asphalt mastics. The results show that fibers improve the deformation resistance of the asphalt mastic, but different fibers show different effects on the low-temperature performance. BF-A and LF show the most significant improvements in high-temperature performance and low-temperature performance, respectively, followed by BF-C, FBF, and BF-B. The morphology of the fibers and the type of infiltration agent on the fiber surface affect the rheological properties of fiber asphalt mastic and lead to different mechanisms of fiber asphalt mastic. The role played by flocculent fiber in asphalt mastic is to stabilize asphalt, while the short-cut fibers can also be lapped to form a spatial network to withstand external loads together with asphalt.

Evaluation of interaction between emulsified asphalt and mineral powder using rheology

Polymer emulsion can significantly improve the performance of emulsified asphalt but can also increase the complexity of the system, especially after mixing with mineral powder. The objective of this study was to evaluate the emulsified asphalt and mineral powder interaction ability based on rheological properties. First, two types of emulsified asphalt and three types of mineral powders were selected to prepare emulsified asphalt residues and mastics, and their dynamic shear rheological (DSR) properties were measured. Second, the K-B-G* and ΔG* models were used to evaluate the influence of temperature and loading frequency on emulsified asphalt and mineral powder interaction ability. Third, the physicochemical interaction between the emulsified asphalt and mineral powder was measured by a Fourier transform infrared (FTIR) spectrometer. Finally, the significance analysis of temperature and loading frequency was conducted by grey relational analysis (GRA). The mold designed in this study was demonstrated effective in obtaining emulsified asphalt residue samples that were suitable for DSR tests at low temperature. K-B-G* and ΔG* indices are consistent in evaluating the interaction ability between emulsified asphalt and mineral powder. The two indices can reflect the influences of temperature and frequency on emulsified asphalt and mineral powder interaction ability, and they also can reflect the difference in the interaction ability of different mineral powders and emulsified asphalt. No new absorption peak in the FTIR spectrum indicated that the physical interaction between emulsified asphalt and mineral powder is primarily the physical action. GRA can be applied to the significance analysis of temperature and loading frequency, and the temperature demonstrates greater influence than the loading frequency. The cationic emulsifier plays the role of anti-stripping agent and enhances the interaction between cationic emulsified asphalt and acid aggregate. The rheological results can guide the selection of the appropriate emulsifier according to the aggregate using in the project.

Modification Mechanism and Rheological Properties of Emulsified Asphalt Evaporative Residues Reinforced by Coupling-Modified Fiber

In order to solve the problems of the smooth surface of basalt fiber and its weak interfacial adhesion with emulsified asphalt cold recycled mixture, a silane coupling agent (KH550) was used to treat the surface of basalt fiber and the effects of treatment concentration and soaking time on fiber modification were studied. The influence of silane coupling-modified basalt fiber (MBF) on the rheological properties of emulsified asphalt evaporation residue was studied at high and low temperatures using three routine index tests: a dynamic shear rheological test (DSR), a bending beam rheological test (BBR), and a force ductility test. The elemental changes of the fiber before and after modification and the microstructure of the emulsified asphalt evaporation residue with the coupling-modified fiber were analyzed by Fourier infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray energy dispersive spectroscopy (EDS), which is used to study the modification mechanism of emulsified asphalt evaporation residue reinforced by coupling-modified fiber. The results indicate that the concentration and soaking time of the silane coupling agent have a great influence on the surface morphology and mechanical properties of the fiber, and that the optimal treatment concentration is 1.0% and the optimal soaking time is 60 min. The addition of coupling-modified fibers can reduce the phase angle and unrecoverable creep compliance of emulsified asphalt evaporation residue, increase the rutting factor and creep recovery rate, and improve the elastic recovery ability and permanent deformation resistance. However, excessive fiber will weaken the ductility of emulsified asphalt at low temperatures. The appropriate content of silane coupling-modified fiber (MBF) is 1.5%. After silane coupling modification, the fiber surface becomes rough and cohesion is enhanced between the fiber and the emulsified asphalt base. Silane coupling-modified basalt fiber (MBF) acts as reinforcement for stability and bridging cracks.

Study on Performance of Wax Warm Mix Asphalt Cracked by Mixed Polyethylene Waste Plastics

In order to study the modified performance of polyethylene waste plastic cracking wax on asphalt, this paper prepared polyethylene wax (PE wax) by catalytic cracking using waste polyethylene as raw material and Ni-based zeolite as catalyst in a pressure reactor under closed conditions. 70# base asphalt was modified with PE wax, and the properties of pyrolysis wax on asphalt under different catalytic cracking time were studied by three indexes test, Brinoll rotary viscosity test, DSC test and dynamic shear rheology test. The test results show that the cracking products of mixed polyethylene waste plastic cracking wax have good viscosity reduction effect on asphalt under different cracking time. After modification, the high temperature performance of asphalt is improved, and the low temperature performance has a certain influence, but it still meets the specification requirements; In the temperature range of 0°C~60°C, the addition of pyrolysis wax can make the phase transformation of matr-ix asphalt more stable.

Effect of ATH/EG Composite Flame Retardant on Properties of High Viscosity Asphalt

In order to improve the flame retardant property of asphalt, ATH (aluminum hydroxide)/EG (expandable graphite) composite flame retardant was obtained by hydrothermal method. The flame retardancy of asphalt was analyzed by oxygen index test. The rheological properties of asphalt were analyzed by dynamic shear rheological test and bending beam rheological test. The research results show that the optimal mix ratio of the compound flame retardant with the best flame retardant synergistic effect is ATH:EG = 1:1. Considering the flame retardancy and rheological properties, the content of ATH/EG composite flame retardant is recommended to be 15%~20%.

Thermal aging behavior characteristics of asphalt binder modified by nano-stabilizer based on DSR and AFM

Abstract In order to clarify the effect of thermal aging on the nano-stabilized modified asphalt binder, TINUVIN 770 (T770) hindered amine light stabilizer of nanoscale was selected as aging modifying agent to prepare modified asphalt. The impact of thermal aging on the rheological properties of T770-modified asphalt was investigated using dynamic shear rheological test of frequency sweep and multiple stress creep recovery test. The surface roughness variation of T770-modified asphalt was characterized by using atomic force microscope throughout the thermal aging process. Furthermore, the typical morphology and parameter features of T770-modified asphalt were identified. The results showed that with the extension of thermal aging time, the high temperature rutting resistance of T770-modified asphalt was improved, while the unrecoverable creep compliance was degraded. When the thermal aging time exceeded 6 h, the bee structure appeared on the surface of T770-modified asphalt. Meanwhile, with the increase in thermal aging time, the special structure formed on the surface of asphalt gradually became smaller. The surface fluctuation difference of T770-modified asphalt reflected the better thermal aging resistance property of T770-modified asphalt than 70# asphalt.

Effect of the binary compound method of TOR promoting dissolution and NaOH solution surface treatment on the performance of rubber asphalt

In view of the problems of poor high-temperature storage stability, high viscosity and easy segregation of rubber powder modified asphalt, the rubber asphalt was prepared using a binary combination of surface treatment crumb rubber powder (CRP) in NaOH solution and a doped trans-polyoctenamer rubber reactant (TOR). Through asphalt softening point, penetration, ductility and segregation tests, a reasonable concentration of 2% NaOH for surface treatment of CRP and an optimum content of 4.5% for TOR were determined. The microscopic mechanism of NaOH and TOR on rubber asphalt was analyzed by tests such as scanning electron microscopy and infrared spectroscopy, and the performance of binary compound modified asphalt (NT-RA) was analyzed using segregation test, bending beam rheometer (BBR), dynamic shear rheology (DSR) and Brinell rotational viscosity test. The results show that NaOH solution could remove impurities on the surface of CRP and improve the interfacial adhesion state between asphalt, and TOR can promote the dissolution of CRP in asphalt. The binary compound action significantly improves the storage stability, low-temperature performance and high-temperature performance of rubber asphalt, and effectively reduces the viscosity of rubber asphalt.