Dynamic Shear Rheology Research Articles

Optimization design and performance evaluation of a novel asphalt rejuvenator

The development of a regeneration agent is one of the key technologies for pavement regeneration and one of the methods to reduce carbon emissions in the transportation field, so it is very necessary to develop a regeneration agent. Based on the composition of asphalt and rejuvenator components, the optimal dosing of extraction oil, plasticizer dioctyl phthalate (DOP), and hydrogenated (carbon 9) C9 petroleum resin was determined by the response surface method, and the suitable dosing of the anti-aging agent was also designed to optimize the orthogonal experiment to prepare the ZJ-I (Zenith Yummy-Invent) rejuvenator with good overall performance. On the basis of the ZJ-I rejuvenator, dynamic shear rheology (DSR), bending beam rheometery (BBR), Fourier transform infrared spectroscopy (FTIR), atomic force microscopy (AFM), and contact angle experiments were used to investigate the effects of the ZJ-I rejuvenator dosing on the high- and low-temperature rheology, chemical structure, surface microscopic morphology, and adhesion between asphalt and aggregate of aged asphalt and to explore the regeneration effect and regeneration mechanism of the ZJ-I rejuvenator. The results showed that the ZJ-I rejuvenator formulated with 83.6% extracted oil, 15% plasticizer DOP, 1.4% hydrogenated petroleum resin, 0.6% antioxidant, and 0.4% light stabilizer has the best regeneration effect, and its optimal dosing is 7% aging degree. It can also improve the adhesion performance of asphalt and aggregate.

A study on effect of oyster shell powder on mechanical properties of asphalt and multiple degrees of modification mechanism

In order to explore the effect of oyster shell powder on the mechanical properties of asphalt, in order to explore the modification mechanism of oyster shell powder on asphalt, based on matrix asphalt, this paper prepared oyster shell powder modified asphalt by adding oyster shell powder with fineness of 40 mesh to matrix asphalt according to 3%, 6%, 9%, 12%, 15% and 18%. Based on the theory of molecular dynamics, the effect of oyster shell powder on the mechanical properties of asphalt was investigated from the molecular level by establishing the molecular model of oyster shell powder modified asphalt with different contents. The modification mechanism of oyster shell powder modified asphalt was analyzed in detail from different scales by infrared spectroscopy, scanning electron microscopy, atomic force microscopy, dynamic shear rheology and viscosity tests. The results show that oyster shell powder has a significant effect on the mechanical properties of asphalt, and the incorporation of oyster shell powder has a positive effect on the improvement of asphalt technical performance. From the research of this paper, when the content of oyster shell powder is 12%, oyster shell powder has the greatest influence on the mechanical properties of asphalt and the best modification effect on asphalt.

Influence of chemically-modified cotton straw fibers on the properties of asphalt mortar

Cotton straw fibers have an important influence on the performance of asphalt mixtures. However, the modification of cotton straw fibers and the performance characterization between the treated cotton straw fibers and asphalt are still lack of understanding. To obtain a better performance improvement technical scheme of cotton straw fibrous asphalt mortar. In this study, sodium hydroxide, silane coupling agent (KH550), and glacial acetic acid (CH3COOH) were used to modify the surface of cotton straw fibers. The modification mechanism and basic properties of the cotton straw fibers were investigated. The effect of the modified fibers on the performance of asphalt mortar was studied using cone penetration, softening point, ductility, and dynamic shear rheology tests. The results showed that the CH3COOH- and KH550-modified fibers produce new acetyl C-O and Si-O deformation vibration absorption peaks, respectively. The three modification methods destroy the hemicellulose structure in the cotton straw fibers. The post-modification surface impurities, roughness, and basic properties of the fibers are reduced, increased, and improved, respectively. An increasing cotton straw fiber dosage continuously improves the high temperature performance of asphalt mortar, but reduces ductility. A fiber dosage of 2 % yields optimized the high temperature performance and the ductility. Under this dosage, the CH3COOH-modified cotton straw fibrous asphalt mortar exhibits a better comprehensive performance. Its shear strength and softening point, as compared to the matrix asphalt increase by 3.21 times and 14.99 %, respectively, and the ductility reduces by 23.94 %, all the measured properties meet the technical specifications of road petroleum asphalt. The results provide more bases for the application of cotton straw fibers in road engineering.

Use of Dynamic Shear Rheology to Understand Soy Protein Dispersion Properties.

Soy flour dispersions are used as adhesives for bonding interior wood laminates, but the high viscosity of these dispersions requires low solids in the adhesive formulations; the greater water content causes excessive steam pressure during hot press manufacturing. This limits the utility of soy adhesives in replacing urea-formaldehyde adhesives; thus, understanding the cause of high soy viscosities is important. Lack of literature on aqueous soy flour dispersion rheology led to our dynamic rheology studies of these dispersions to understand high viscosity and the effect of various additives. Even at low soy solids, the elastic nature outweighs the viscous properties at low shear, although increasing the shear results in shear-thinning behavior after the yield point. At even higher shear, beyond the flow point where the storage and loss moduli cross, some of the dispersions show an additional shear thinning transition. The comparison of the rheological properties of aqueous dispersions of the soy flour and protein isolate, and another natural protein, ovalbumin from egg whites, led to a better understanding of different types of rheological behaviors. The experimental observations of two observed shear thinning events for soy are consistent with the model of dispersed particles, forming clusters that then form large scale flocculants.

Study on the Performances of Waste Battery Powder Modified Asphalt and Asphalt Mixture.

As an asphalt modifier, waste battery powder (WBP) has been proven to be possible. This paper studies the modification effect of WBP on asphalt. The Flight Test Instrumentation Requirements (FITR) of WBP, Dynamic Shear Rheology (DSR) test, and Full Section Fracture Energy Test (FSFET) of asphalt are carried out. The high-temperature rheological properties and low-temperature properties of WBP modified asphalt are analyzed. The high-temperature stability, low-temperature crack resistance and water stability of WBP modified asphalt mixture are tested. The research results show that the modification of asphalt by WBP is essentially physical modification but the mixing of WBP has a certain enhancement effect on the bond energy of the methylene group, which is helpful to improve the technical performance of modified asphalt. The proportion of elastic components in asphalt can be significantly increased by adding WBP, thus enhancing the deformation resistance of asphalt under high-temperature conditions. The dynamic shear modulus of 10% waste battery powder is about 1.5-2.0 times that of 0% waste battery powder. The mixing of WBP reduces the proportion of viscous components in asphalt which is unfavorable to the crack resistance under low temperatures. The greater the amount of WBP, the smaller the fracture energy density, the content of WBP is 6% and 10%, the fracture energy density is about 60-80% and 40-60% of the original asphalt, and the low temperature cracking resistance of asphalt decreases. The modification effect of WBP on asphalt is much lower than that of SBS.

Preparation of an eco-friendly de-icing filler and its effects on the performance of different asphalt mastic

In order to solve the problems of environmental pollution and corrosion of road facilities by chloride ion de-icing agents, eco-friendly acetate de-icing filler for asphalt pavement was prepared in this paper using response surface methodology (RSM). The basic performance of eco-friendly de-icing filler was evaluated by de-icing test, thermogravimetry and scanning electron microscope (SEM). Four de-icing asphalt mastic were prepared by eco-friendly de-icing filler with matrix asphalt, SBS asphalt, high viscosity asphalt and asphalt rubber. The rheological and cohesive properties of the four de-icing mastic were analyzed using dynamic shear rheological (DSR) tests and binder bond strength (BBS) test. Fourier Transform infrared spectroscopy (FTIR) and Fluorescence microscope (FM) were used to investigate the microscopic interaction mechanism and compatibility of eco-friendly de-icing filler with the four asphalt. The test results show that eco-friendly de-icing filler is similar to the mineral filler in particle morphology and gradation. The thermal stability, ice melting performance and environmental performance of eco-friendly de-icing filler can satisfy the practical application. The phase angle and rutting factor of de-icing asphalt mastic increased to different degrees, but the adhesion and self-healing properties were weakened. The cohesive strength of matrix asphalt, SBS asphalt, high viscosity asphalt, and asphalt rubber mastic decreased by 4.49%, 6.37%, 14.24% and 10.26% respectively, and the healing rate decreased by 4.17%, 5.32%, 2.78% and 8.41% respectively. New absorption peaks appeared in the FTIR image, indicating that eco-friendly de-icing filler accelerated the aging of asphalt mastic. The FM pictures showed that the high viscosity asphalt was more compatible with eco-friendly de-icing filler and that the asphalt rubber was the worst. The results of this paper show that de-icing asphalt mastic using high viscosity modified asphalt has the best comprehensive performance.

Evaluation of the field-aged performance of foamed warm mix asphalt: Comparisons with hot mix asphalt

The foamed warm mix asphalt (FWMA) has been widely used as a sustainable construction technique in pavement engineering, yet has not yet been fully studied for its aging performance or durability. Here we aim to examine and evaluate the performance variation characteristic of FWMA compared with conventional hot mix asphalt (HMA) under long-term service conditions. The performance evolution of FWMA core samples drilled from four highways was compared to that of ordinary HMA, which was simultaneously constructed. Fourier transform infrared (FTIR), dynamic shear rheology (DSR), and bending beam rheometer (BBR) tests were respectively performed to evaluate the aging degree, high-temperature, and low-temperature rheological characteristics. The results demonstrated that the aging resistance of foamed WMA was slightly diminished under construction conditions with no temperature reduction. With increased service time, the rheological characteristics of FWMA were enhanced at high temperatures, while deteriorated at low temperatures. The foaming water and service time were primary determinants of the aging as well as high and low-temperature rheological properties of FWMA without temperature construction reduction. Additionally, the aging degree of FWMA under short-term and long-term service was smaller than HMA when the construction temperature decreased. The rheological characteristics of FWMA were inferior to those of HMA during both short-term and long-term service stages. Under conditions of temperature reduction, foaming water and mixing temperature exhibited a considerable influence on the aging and rheological properties of FWMA at high and low temperatures. Therefore, the amount of water used for foaming and the temperature of production should be strictly control in the foamed warm mix asphalt technology.

A new flame retardant and its effect on the asphalt mixture

To alleviate the problem of decomposition products of organic flame retardants with toxic, inorganic flame retardants were used to prepare flame retardant modified asphalt (FRA), but the traditional inorganic flame retardants have a significant flame retardancy only with a high dosage, and too high dosage would bring serious adverse effects on the pavement performance of asphalt mixture. For this, to avoid the side effects of inorganic flame retardants, a compound flame retardant was developed by orthogonal experiment method to alleviate the problem of high dosage of inorganic flame retardants, and to have a relatively significant flame retardancy. The flame retardancy was studied by conventional performance test, separation test, rotational viscosity (RV) test, dynamic shear rheology (DSR) test, limiting oxygen index (LOI) test, thermogravimetry (TG) test, pavement performance test, and combustion test. The results show that with the addition of self-developed flame retardant (WZRJ-I), the PI of FRA was increased by 23.4∼40.4 % compared with virgin asphalt, the LOI was increased by 24.7∼46 %, the rutting factor was increased by 12.6∼27.9 %, the thermal decomposition parameters were significantly improved at all stages, the burning time was reduced by 39 s∼53 s, the mass loss was reduced by 11.9∼15.4 %, which indicated that the addition of WZRJ-I was conducive to improve the flame retardancy and high temperature performance. Finally, the prediction equation model of combustion performance index and burning time of asphalt mixture was established, and the effect of burning time on the residual pavement performance of asphalt mixture was quantitatively analyzed.

The synergistic effect of waste engine oil and organic montmorillonite on properties of bitumen: Conventional, high-temperature rheological, and self-healing

In order to conserve non-renewable natural resources, recycling waste engine oil (WEO) in bitumen can help lower CO2 emissions and advance the environmental economy. This paper makes an effort to investigate the viability of WEO and organic montmorillonite (OMT) to enhance the high-temperature rheological and self-healing of bitumen binder. Conventional tests and dynamic shear rheology (DSR) test were used to examine the influence of WEO/OMT on the traditional performance and high-temperature rheological properties. Based on a fatigue-healing test, evaluation indicators such as fatigue life recovery (FLR), modulus recovery (MR), and dissipated energy recovery (DER) were chosen to determine the degree of healing of bitumen. The mechanism was revealed by the atomic force microscope (AFM). Finally, a radar chart was employed to analyze the comprehensive properties of WEO/OMT modified bitumen. The results indicate that WEO modified bitumen loses ductility and penetration when OMT is added while increasing softening point and high-temperature performance. Compared to original bitumen, the rutting factor of bitumen modified with 3% WEO and 2% OMT has the most significant increase by 31.2%. The performance of the bitumen binder during fatigue and self-healing is improved by the addition of OMT and WEO. Regardless of the OMT level, bitumen modified with 9% WEO shows a significant improvement in FLR, MR, and DER compared to the original bitumen. In conclusion, the inclusion of WEO/OMT in bitumen offers a fresh approach to developing sustainable pavement materials.

The Synergistic Effect of Polyphosphates Acid and Different Compounds of Waste Cooking Oil on Conventional and Rheological Properties of Modified Bitumen

In order to conserve non-renewable natural resources, waste cooking oil (WCO) in bitumen can help lower CO2 emissions and advance the environmental economy. In this study, three different components of WCO were isolated and then, together with polyphosphoric acid (PPA), used separately as bitumen modifiers to determine the suitability of various substances in WCO with PPA. Conventional tests, including penetration, softening point temperature, and ductility, and the dynamic shear rheology (DSR) test, including temperature sweep and frequency sweep, were used to evaluate the influence of WCO/PPA on the traditional performance and rheological properties at high and low temperatures. The results indicate that WCO reduced the ductility and penetration value, when the use of PPA increased the softening point temperature and high-temperature performance. Compared to reference bitumen, the rutting factor and viscous activation energy (Ea) of bitumen modified with 4% WCO and 2% PPA has the most significant increase by 18.6% and 31.5, respectively. All components of WCO have a significant impact on improving the low-temperature performance of PPA-modified bitumen. The performance of the composite-modified bitumen at low temperatures is negatively affected by some waxy compounds in WCO, such as methyl palmitate, which tends to undergo a solid-liquid phase change as the temperature decreases. In conclusion, the inclusion of WCO/PPA in bitumen offers a fresh approach to developing sustainable pavement materials.

Thermal oxidative aging mechanism of lignin modified bitumen

Lignin is the most abundant renewable resource in nature, which can be applied to not only improve resource utilization but also improve bitumen road performance. In this study, the evolution of lignin during thermal-oxidative aging of bitumen was investigated by dynamic shear rheology test (DSR), thermogravimetric test (TG) and Fourier transform infrared spectroscopy (FTIR). The thermo-oxidative aging mechanism of lignin modified bitumen was analyzed. The results show that lignin-modified bitumen had better aging resistance than the virgin bitumen. Meanwhile, the changes of functional group indices at 1460 cm−1, 1512 cm−1, and 1600 cm−1 in the infrared spectra proved that the thermal-oxidative aging mechanism was the decomposition of lignin itself under the action of thermal oxygen, which inhibited the aging process of bitumen.

Aging Characterizations of Modified Asphalt Binders Based on Low Field Nuclear Magnetic Resonance (LF-NMR).

Styrene-butadiene-styrene block copolymer (SBS) and crumb rubber modifier (CRM) are commonly used modifiers to modify asphalt binders. The aging of modified asphalt binders is an important factor affecting their performance. In this paper, the effects of the two modifiers (i.e., SBS, CRM) on the aging of modified asphalt binders were studied by using low field nuclear magnetic resonance (LF-NMR) technology and dynamic shear rheological (DSR) tests. Test results showed that when T2, a parameter of relaxation time from NMR test, was within 2.2 milliseconds, the relaxation peak of both modified and unmodified asphalt binders tested showed two peaks (i.e., "M" shape), and when it was greater than 2 milliseconds, extra peaks appeared only in the modified asphalts. These extra peaks gradually disappeared with increased aging; the modifiers carried signal intensities of their own. The addition of a modifier changes the law of "the greater the viscosity of asphalt, the shorter the T2 relaxation time". With the aging process, the normalized peak area (NPA) from NMR decreased, and rutting resistance factor from DSR increased. However, the NPA of modified asphalt increased after the PAV test, which may be related to the change of H semaphore. The rheological properties of the asphalt binders before and after aging were well-correlated with the NPA of T2.

Study on the Effect of Ultraviolet Absorber UV-531 on the Performance of SBS-Modified Asphalt.

Asphalt pavements at high altitudes are susceptible to aging and disease under prolonged action of UV light. To improve their anti-ultraviolet aging performance, UV-531/SBS-modified asphalts with UV-531 dopings of 0.4%, 0.7%, and 1.0% were prepared by the high-speed shear method, and the effect of UV-531 on the conventional performance of SBS-modified asphalt before aging was studied by needle penetration, softening point and 5 °C ductility tests. The high- and low-temperature rheological properties of UV-531/SBS-modified asphalt before and after aging were also analyzed by high temperature dynamic shear rheology test and low-temperature glass transition temperature test. Finally, the effect of UV-531 on the anti-aging performance of SBS-modified asphalt was evaluated by three methods, including rutting factor ratio, viscosity aging index, and infrared spectroscopy. The results show that with the increase of UV-531 doping, the needle penetration and 5 °C ductility show an increasing trend, but the effect on the softening point is small. The high temperature stability of SBS-modified asphalt is not much affected by the addition of UV-531, and the low-temperature stability is improved, and when 0.7% UV absorber is added, SBS-modified asphalt shows better low-temperature performance. The results of all three evaluation methods show that the addition of UV-531 significantly improved the anti-UV aging performance of SBS-modified asphalt, with the amount of 0.7% providing the asphalt with the best anti-UV aging performance. The results of the study can provide an important reference for improving the anti-ultraviolet aging performance of SBS-modified asphalt.

Composition and Performance Evaluation of SBS/SBR Modified Emulsified Asphalt for Tack Coat on Airport Pavement

Asphalt concrete pavement is gradually being adopted in cement concrete pavement repair and paving due to its short construction period and low vibration to aircraft. However, the performance of the interlayer binder is the critical factor affecting the paving effect. For the preparation of interlayer high-performance emulsified asphalt suitable for airport pavement, the type and dosage of modifier and emulsifier were taken as factors and levels for the orthogonal test. Combined with the evaporation residue, softening point, penetration, ductility, and Engla viscosity indexes, the range analysis was carried out to determine the optimal dosage of modifier and emulsifier. Furthermore, the dynamic shear rheology test (DSR), fluorescence microscope test, TG-DSC test, and shear and tensile tests were used to evaluate the technical properties of SBS/SBR modified emulsified asphalt. These results showed that the best blending mass ratio of SBS/SBR modified emulsified asphalt is 1.5% SBS + 3% SBR + 1% emulsifier. Temperature sweep at 48°C, compared with SBS/SBR modified emulsified asphalt, the complex shear modulus (G ∗ ) of SBS/SBR modified emulsified asphalt increased by 71% and 75%, while the rutting factor(G ∗ /sinδ) increased by 83% and 86%, respectively, which indicates that its shear deformation resistance and rutting resistance have been significantly improved. The Han curve indicates that the SBS/SBR modifier has excellent compatibility with asphalt and can maintain a stable state at a lower frequency. Before demulsification, SBS/SBR modifier and emulsified asphalt formed a stable spatial network structure. After demulsification, the continuous phase and the dispersed phase were more closely integrated, so that the emulsified asphalt exhibited better bonding performance. At different temperatures, by increasing the spraying volume, the shear and tensile strength of SBS/SBR modified emulsified asphalt increased first and then decreased. At 25°C, the maximum shear and tensile strengths are 0.86 MPa and 0.65 MPa. This study demonstrated that SBS/SBR modified emulsified asphalt formed a stable spatial network structure, giving it excellent technical properties, and can be widely used for tack coat on airport pavement.

Multi-Scale Characterization of High-Temperature Properties and Thermal Storage Stability Performance of Discarded-Mask-Modified Asphalt

In the context of the global pandemic of COVID-19, the use and disposal of medical masks have created a series of ethical and environmental issues. The purpose of this paper is to study and evaluate the high temperature properties and thermal storage stability of discarded-mask (DM)-modified asphalt from a multi-scale perspective using molecular dynamics (MD) simulation and experimental methods. A series of tests was conducted to evaluate the physical, rheological, thermal storage stability and microscopic properties of the samples. These tests include softening point, rotational viscosity, dynamic shear rheology (DSR), Fourier transform infrared (FT-IR) spectroscopy and molecular dynamics simulation. The results showed that the DM modifier could improve the softening point, rotational viscosity and rutting factor of the asphalt. After thermal storage, the DM-modified asphalt produced segregation. The difference in the softening point between the top and bottom of the sample increased from 2.2 °C to 17.1 °C when the DM modifier admixture was increased from 1% to 4%. FT-IR test results showed that the main component of the DM modifier was polypropylene, and the DM-modified asphalt was mainly a physical co-blending process. MD simulation results show that the DM modifier can increase the cohesive energy density (CED) and reduce the fractional free volume (FFV) of asphalt and reduce the binding energy between base asphalt and DM modifier. Multi-scale characterization reveals that DM modifiers can improve the high temperature performance and reduce the thermal storage stability of asphalt. It is noteworthy that both macroscopic tests and microscopic simulations show that 1% is an acceptable dosage level.

Thermo-mechanochemical recycling of waste polypropylene into degradation products as modifiers for cleaner production and properties enhancement of bitumen

Recycled polypropylene (rPP) wastes have been used to improve the high-temperature performance of asphalt. However, the high melting temperature of rPP does not match the conventional mixing temperature of bitumen, resulting in more energy consumption and emissions. Therefore, this study adopted dicumyl peroxide (DCP) to chemically degrade the rPP through a melt-shear processing method to obtain the corresponding modifiers (rPPM) with better flowability at a lower temperature. Torque rheology, melt flow rate (MFR) and thermogravimetry analysis (TGA) characteristics of rPPM incorporated with different dosages (1‰, 3‰, and 5‰) of DCP were compared to that of rPP. Correspondingly, the rPPM modified asphalt (rPPMA) were characterized by penetration, softening point, viscosity, and the dynamic shear rheology (DSR) tests. The TGA test showed that the rPPMs have a lower thermal stability as compared to rPP, and the MFR of rPPM can be up to 1900% larger than that of the rPP. The rPPMs can contribute to increasing the softening point and reducing by almost 50% penetration of virgin binder, which are reflected that they can improve the high-temperature performance of virgin binder. The DSR results stated that rPPM can provide a slightly improved deformation resistance and a lower anti-fatigue characteristic, comparative capacities, as well as a relatively lower deformation resistance and higher fatigue failure to the virgin binder, respectively. Accordingly, 3‰ DCP is optimally recommended to degrade rPP to obtain the modifier for the cleaner production and enhancement of modified binders.

The Utilization of Waste Toner as a Modifier in Trinidad Asphalts

As more persons are adjusting to home working in light of the COVID-19 pandemic, there has been a significant increase in the use of technology. Trinidad and Tobago, like many other Small Island Developing States, began exploring strategies in the areas of recycling and reuse techniques to mitigate negative environmental impacts from the disposal of waste toners. The reuse of waste toners as a performance enhancer in bituminous materials has successfully been achieved in foreign jurisdictions; however, the lack of research on the utilization of the indigenous Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB) has stymied the application of this strategy locally. The influence of four waste toners (A, B, C, and D) on the rheological properties of an unmodified TLA/TPB paving binder was measured using the dynamic shear rheology (DSR) testing technique. The addition of waste toners noted improvements in the rheological parameters of stiffness, elasticity, and viscosity, exhibiting superior temperature susceptibility. Of great interest was the observation at 90 °C, where the modified paving binders containing 5% Toner C and 20% Toner D were elastically superior to the world-renowned TLA. This study demonstrated the potential of utilizing waste toner as a bitumen modifier, providing an innovative, sustainable disposal option.

Rheological, chemical and short-term aging properties of waste polyurethane particles modified asphalt binder with or without SBS

In order to effectively dispose of waste polyurethane (WPU) and obtain modified asphalt binders with excellent properties, WPU particles are used to modify asphalt binder. Conventional properties and thermal storage stability of asphalt binders are analyzed, their rheological properties and creep recovery properties are tested by the dynamic shear rheological (DSR). Microstructure, molecular weight and chemical structure of the asphalt binders are analyzed by fluorescence microscopy (FM), gel permeation chromatography (GPC) and fourier transform infrared spectroscopy (FTIR) respectively. Results show that low temperature crack resistance of base asphalt binder is improved due to WPU particles addition, which impairs the property of SBS modified asphalt binder. After short-term aging, the Jnr at 3.2 kPa (Jnr3.2) of modified asphalt binder with WPU particles is less than 2.0 kPa−1. And Jnr3.2 of base asphalt binder decreases by 52.4 % due to WPU particles addition, it is 25.5 % for SBS modified asphalt binder. The thermal storage stability of WPU particles modified asphalt binder is poor and improved by 42.3 % due to the SBS use. The rod-shaped WPU particles are found in modified asphalt binder without SBS, and their structure is destroyed during aging, forming numerous small particles and small molecular products, which improve rutting resistance of asphalt binder. When aged at 150 °C, 163 °C and 180 °C, addition of WPU particles makes aging resistance of base asphalt binder increase by 0.9 %, 1.5 % and 1.2 % respectively, which impairs the aging resistance of SBS modified asphalt binder by 0.9 %, 5 % and 5.3 % respectively. FTIR results manifest decomposition reaction presented in WPU during preparation and aging, forming products with CO.

Property Characterization of Anti-Aging Additives and Modified Asphalt Based on Long-Term Aging Behavior

In order to achieve the good application of hindered amine light stabilizer (HALS) in the long-term aging control of asphalt pavement material, Tinuvin770 and Tinuvin622 light stabilizers were selected as modifiers for asphalt. The microstructure and characteristics of hindered amine light stabilizers were characterized by FIB-SEM. The elemental composition and relative content of hindered amine light stabilizers were studied by means of EDS analysis. The functional group composition of hindered amine light stabilizers was analyzed based on Dynamic-FTIR. On this basis, light stabilizer modified asphalt was prepared, and the effect of hindered amine light stabilizer on the thermal rheological properties of asphalt binder during UV aging period was studied by dynamic shear rheology (DSR). The changing law of low temperature rheological properties of hindered amine light stabilizer modified asphalt was evaluated by low temperature bending beam rheological test (BBR). The results showed that the hindered amine light stabilizer could capture the free radicals formed during the photodegradation of asphalt when subjected to ultraviolet aging. Under the impact of ultraviolet aging, hindered amine light stabilizer could improve the high temperature performance of asphalt binder. Furthermore, HALS could achieve the improving effect on the low temperature rheological properties and long-term aging performance of asphalt pavement materials.

The effect of morphology of ZnO particle on properties of asphalt binder and mixture

To study the effects of the morphology of ZnO particles on the properties of asphalt binder and asphalt mixture, the micro ZnO particles with different morphologies (agglomerate, sphere, rod and flower), whose average size were 2 µm, were made by the homogeneous precipitation and hydrothermal methods. A series of tests, including the softening point, bending beam rheometer (BBR), dynamic shear rheological (DSR), Marshall test, rutting test and so on, were used for evaluating the properties of asphalt binder and asphalt mixture. The analysis of variance (ANOVA) and the maximum relative difference (MRD) were introduced to study the effects of the morphology of ZnO particles on the properties of asphalt binder and asphalt mixture. Finally, the optimal morphology of the ZnO particle was recommended. The results show that the morphology of the ZnO particle has a significant effect on the rutting factor, has an effect on the viscosity in the situation of the dosages of SBS are 0% and 4%, has no effect on the low temperature ability of asphalt binder. In terms of asphalt mixture, the morphology of the ZnO particle has a noticeable effect on the high temperature stability, has an effect on the low temperature ability, has almost no effect on the water stability of asphalt mixture. Furthermore, the rod-like ZnO particles are more conducive to promote the properties of asphalt binder and asphalt mixture. As a result, the rod-like ZnO particle is recommended.