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Fatigue cracking is a common form of flexible pavement distress, which generally starts and spreads through bitumen. To address this issue, self-healing elastomer (SHE) modified bitumens were elaborated to assess whether these novel materials can overcome the neat asphalt (NA) fatigue performance and whether the current failure definition, failure criterion, and fatigue-restoration criteria can fit their performance. All bitumens were subjected to short-term and long-term aging. Linear amplitude sweep (LAS) test, LAS with rest period (LASH), and simplified viscoelastic-continuum-damage (S-VECD) model were utilized to appraise the behavior of the mentioned bitumens. The results showed that maximum stored pseudo-strain energy (PSE) and tau (τ) × N (number of loading cycles) failure definitions exhibited high efficiency to accommodate the fatigue life of NA and SHE-modified bitumens. Both failure criteria identified that SHE-modified bitumen (containing 1% of SHE) showed the highest increment of fatigue performance (67.1%) concerning NA. The failure criterion based on total released PSE, in terms of the area under the released PSE curve, was the only failure concept with high efficiency (R2 up to 0.999) to predict asphalt binder fatigue life. As well, the current framework to evaluate bitumen self-restoration failed to fully accommodate asphalt binder behavior, because bitumen with higher restoration could not exhibit greater fatigue performance. Consequently, a new procedure to assess this property including fatigue behavior was proposed, showing consistent results, and confirming that SHE-modified bitumen (containing 1% of SHE) exhibited the highest increment of fatigue performance (154.02%) after application of the rest period. Hence, the optimum SHE content in NA was 1%. Furthermore, it was found that a greater number of loading cycles to failure ( N f ) did not ensure better fatigue performance and stored PSE influenced the bitumen fatigue behavior. [ABSTRACT FROM AUTHOR]

In this paper, styrene butadiene rubber (SBR) was utilized to improve the low-temperature performance of Buton-rock asphalt (BRA)-modified asphalt. Firstly, the optimum content of SBR modifier agent was determined by basic mechanical property tests, including penetration, ductility, and soft point tests. The comprehensive road performance, including high- and low-temperature performance, moisture resistance, and antifatigue performance at a low-temperature condition, of SBR-BRA-modified asphalt mixtures was evaluated by comparison with a base asphalt mixture, SBR-modified asphalt mixture, BRA-modified asphalt, and styrene-butadiene-styrene (SBS)-modified asphalt mixture. The fatigue test under the experimental temperature of −10°C and loading frequencies of 0.01, 0.1, 1, 5, and 10 Hz were designed to evaluate the antifatigue capacity of SBR-BRA-modified asphalt mixture under the low-temperature region. The S-N fatigue equation with the stress ratio related to loading rates was proposed to characterize the fatigue property of asphalt mixtures and reveal the different effects of loading frequency and materials on the fatigue property of asphalt mixtures. The tests results demonstrated that the SBR-BRA-modified asphalt has an equal road performance to SBS-modified asphalt. Analyzed by the S-N fatigue equation with the stress ratio related to loading rates, the fatigue test results under different loading frequencies could be fitted to a fatigue curve, and the fatigue curves of different asphalt mixtures exist at an angle and intersect at point (1,1). [ABSTRACT FROM AUTHOR]

In this paper, two types of Styrene-Butadiene-Rubber (SBR) were adopted to modify the Buton-rock asphalt (BRA) modified asphalt, aiming to select a binder with excellent comprehensive performances. Powder SBR and latex SBR (0%, 2%, 4%, 6%, and 8%), were mixed with the 15 w% BRA modified asphalt. The characterization of rheological properties included dynamic shear rheometer, rotational viscometer, and bending beam rheometer test. The short-term aging performance was characterized by the ratio of the complex shear modulus from the un-aged and rolling thin film oven (RTFOT) -aged asphalt. Besides, Fourier transform infrared spectroscopy and scanning electron microscopy were conducted to reveal the modification mechanism. It was observed that the two kinds of BRA-SBR modified asphalt had preferable anti-crack capacity at low temperatures than the BRA modified asphalt. Compared with latex SBR, the powder SBR significantly improved the high-temperature performance, and the anti-aging capacity was stable. However, some negative influence occurred by the addition of latex SBR on the anti-rutting and short-term aging property. According to the micro-mechanism analysis, adding powder SBR and latex SBR into BRA modified asphalt was a physical blending process, and they improved the dispersion state of BRA in asphalt. Based on the comprehensive performance, the recommended combination was BRA and powder SBR. [ABSTRACT FROM AUTHOR]

Highlights • The strength and fatigue tests of asphalt mixtures were implemented. • The evolution patterns of strength with loading rate were revealed. • The unified fatigue model of asphalt mixtures was established. • The behavior of thermal fatigue and strength failure was integrated. Abstract In order to reveal the thermal fatigue behavior of asphalt mixtures under low temperature conditions, the four-point bending beam tests of strength and fatigue were carried out. The asphalt mixtures are typical viscoelastic materials whose fatigue properties are significantly influenced by low loading frequency. Thus, the fatigue tests under low loading frequency were used to simulate the thermal fatigue of asphalt mixtures. Based on the nominal stress ratio (not considering the effect of loading rate on the strength value) and the real stress ratio (the strength value corresponding to the loading rate of fatigue test), the fatigue equations of asphalt mixtures under low temperature and low frequency conditions were established. The flexural strengths of the four-point bending beam tests at different loading rates at 0 °C, −10 °C and −20 °C were studied. The results show that the flexural strength of asphalt mixtures expresses a power function on the pattern of variation with the loading rates. The intersection of fatigue curve characterized by the nominal stress ratio and the abscissa axis is much larger than 1. The fatigue curve based on the nominal stress ratio cannot be extended to fatigue failure point (1,1). But the fatigue curve characterized by the real stress ratio can be extended to the strength failure point, whose fatigue life is 1. So, the behavior of strength failure and fatigue failure was integrated. The uniform characterization model of fatigue equations for asphalt mixture under low temperature and low loading frequency conditions was realized, which means that the fatigue equations and curves under different loading frequencies could be characterized by one equation and one curve. The results can provide a theoretical basis for predicting the thermal fatigue performance of asphalt mixtures under low temperature conditions more accurately. [ABSTRACT FROM AUTHOR]

• The added Lucobit additive can increase the complex modulus and reduce the viscosity of the rubberized asphalt binder. • The shear stress-sensitivity of the rubberized asphalt binder can also be reduced by the added Lucobit additive. • The modification mechanism of the ECB the asphalt binder were unveiled by the combined FTIR, TGA and AFM tests. • The added Lucobit additive can further enhance anti-aging performance of the rubberized asphalt binder. Applying waste tire rubber powder to modify the asphalt binder is a promising protocol to achieve sustainable pavement materials. This study aims to examine the feasibility of using Lucobit type asphalt additive in the rubberized asphalt and further enhance its performance. The 90# asphalt binder and the rubber powder with 30 mesh were selected to prepare the rubberized asphalt. Two Lucobit adding ratios (5% and 10%) were then selected for the modification of three types rubberized base binder (Rubber replacement ratios 15%, 20%, and 25%). The modified asphalt binder was prepared under 180 ± 5 ℃ by using the high-speed shear mixer under 5000 rpm for 2 h. Then the FTIR and TGA tests were conducted for the phase analysis of the asphalt co-modified with rubber powder and Lucobit. The test results indicated the modification mainly belong to the physical blending instead of chemical bonding. Further study with DSR test indicated the added Lucobit can further enhance the high-temperature stability of the rubberized asphalt. Further study based on Multiple Stress Creep Recovery (MSCR) test indicated the anti-rutting performance of the asphalt binder would be enhanced while the sensibility of asphalt binder to shear stress would be reduced with the added Lucobit. Finally, the topography analysis on the original and aged binders were analyzed with Atomic Force Microscopy (AFM) test. The results indicated obviously reduced bee-like structure can be observed in the samples with Lucobit, which is in accordance with the measured complex modulus after aging tests. Overall, this study indicates the added Lucobit can further enhance the high-temperature stability, antiaging performance, and reduce shear stress sensitivity of the asphalt binder. [ABSTRACT FROM AUTHOR]

• The waste leather can enhance the rotational viscosity of the asphalt binder. • The addition of waste leather powder can enhance the high-temperature properties. • The modification with the waste leather is mainly a physical process. This study analyzed the feasibility of modifying the asphalt binder with the waste leather (WL). The 70# base asphalt was selected as the base matrix and four samples with different waste leather content were prepared. The test results indicated that the rotational viscosity of the waste leather modified asphalt was obviously higher than that of the original binder. Furthermore, it is found that the added waste leather increases the elastic component of the asphalt through the dynamic shear rheometer (DSR) test, thus enhances the high-temperature rheological properties and creep recovery ability of the asphalt. The modification with waste leather can also enhance the anti-aging properties of the asphalt and the enhancement effect generally increases with the leather content. The fourier transform infrared spectroscopy (FTIR), results indicate the modification with the waste leather is mainly a physical process without changing the chemical structure of the asphalt binder. This study pcreates new recycling routes for the waste leather and provides a considerable reference for the application of the waste leather modified asphalt binder. [ABSTRACT FROM AUTHOR]

Limited non-renewable resources and deteriorating ecological environment have emphasized the significance of the effective utilization of biomaterials. Many studies have specified that fish scales (FS) possess potential applications as cleaner production in various industrial sectors. However, research on the effect of this eco-friendly and sustainable biomaterial on asphalt has not been reported. Thus, this study aims to investigate the effect of fish scale powder (FSP) on the performance of asphalt binders. Four types of fish scales modified asphalts (FSMA) were prepared by adding different contents of FSP to 70# base asphalt (4%, 8%, 12%, and 16% by weight of the base asphalt). Rotational viscometer (RV), dynamic shear rheometer (DSR), and bending beam rheometer (BBR) were employed to characterize the rheologic behavior of FSMA. The phase separation and sessile drop tests were carried out to evaluate the storage stability and adhesion of FSMA. In addition, the chemical characteristics were investigated by Fourier transform infrared (FTIR) spectroscopy. It was found that FSP enhanced the adhesion, viscoelastic properties, temperature susceptibility, and resistance to permanent deformation of asphalt. Moreover, it was discovered that FSP at low content had little effect on the aging, fatigue, and cracking resistance of the asphalt. Besides, there was a physical mixing between FSP and asphalt binder, and the mixture was a storage-stable product. Overall, it is promising and feasible to use FSP as a bio-modifier for asphalt binders and reduce waste treatment costs. This method is a sustainable utilization of fish scale waste. [ABSTRACT FROM AUTHOR]

Rubberized asphalt (RA) has been successfully applied in road engineering due to its excellent performance; however, the most widely used rubber content is about 20%.To improve the content of waste rubber and ensure its performance, seven rubberized asphalts with different powder content were prepared by high-speed shearing. Firstly, penetration, softening point, and ductility tests were carried out to investigate the conventional physical features of high-content rubberized asphalt (HCRA). Then, the dynamic shear rheometer test (DSR) was conducted to estimate the high-temperature rheological properties. The bending beam rheometer test (BBR) was carried out to evaluate the low-temperature rheological performance. Finally, combined with the macroscopic performance test, the modification mechanism was revealed by the Fourier transform infrared reflection (FTIR) test, and scanning electron microscope (SEM) analysis was used to observe the microscopic appearance before and after aging. The results show that rubberized asphalt has excellent properties in high- and low-temperature conditions, and fatigue resistance is also outstanding compared with neat asphalt. As the crumb rubber content increases, it is evident that the 40% RA performance is the best. The low-temperature properties of HCRA are better than the traditional 20% rubberized asphalt. This study provides a full test foundation for the efficient utilization of HCRA in road engineering. [ABSTRACT FROM AUTHOR]

The quickly accumulated crayfish shell waste in China has led to severe environmental issues and recycling pressure. This study aims to build an efficient protocol by utilizing waste crayfish shell powder in the production of high-performance and sustainable asphalt binder. The asphalt binder modified with different contents of crayfish shell powder (5%, 10% and 20% mass ratio to control asphalt, respectively) were first prepared at the temperature of 140oC–150 °C. Then the softening point and the penetration of the prepared samples were implemented to compare the stiffness difference between the modified and original asphalt binder. The results indicated that the added shell powder increased the softening point and decreased the penetration of the control asphalt. Furthermore, the high-temperature stability of the asphalt binder was examined by the dynamic shear rheometer (DSR) tests. The DSR results revealed that adding shell powder could enhance the rutting resistance of the asphalt binder by decreasing the phase angle δ, increasing the dynamic shear modulus |G∗| and finally enhancing the rutting factor |G∗|/sinδ. After that, to compare the creep performance between the control and modified asphalt binder, the multiple stress creep recovery (MSCR) tests were employed. The results of the MSCR test showed that at the same temperature, the percent recovery was higher while the non-recoverable creep compliance J nr of modified asphalt was lower than those of the control binder. These results indicated that the added crayfish shell powder could increase the stiffness, improve the high-temperature stability and creep resistance of the asphalt binder. Finally, fourier transform infrared spectroscopy (FT-IR) test results implied that the added CS would not affect the chemical structure of the asphalt binder, and the modification was mainly a physical process. The novelty and limitation of this study have also been detailedly explained in the discussion part. The test results could provide a reference for the engineering application of the crayfish shell powder modified asphalt material and lead to both a cleaner and greener product. [ABSTRACT FROM AUTHOR]

Acrylamide with a double bond and amide group can not only copolymerize with macromolecules of crumb rubber but also react with acidic groups in asphalt, so it was selected as a modifier to activate crumb rubber through chemical graft action. The purpose is to improve the compatibility between crumb rubber and asphalt and thus improve the rheological properties and storage stability of rubber asphalt. Infrared spectroscopy (IR) and scanning electron microscopy (SEM) were used to characterize the crumb rubbers and their modified asphalt. It was found that the crumb rubber of grafting acrylamide had better compatibility in asphalt due to its larger specific surface area and chemical reaction with asphalt. In addition, the high temperature rheological test, low temperature creep test, and polymer separation test were carried out to study the effect of grafted activated crumb rubber on the properties of modified asphalt. The results showed that compared with modified asphalt with common crumb rubber (CRMA), the rheological properties and storage stability of modified asphalt with grafting activated crumb rubber (A–G–R) were improved significantly. The results of microscopic and macroscopic tests show that the activated rubber particles have a larger contact area with asphalt due to a rougher surface and the chemical cross-linking between rubber particles and asphalt further strengthens their interaction. Therefore, there is a relatively stable blend system formed in modified asphalt, and its performance of modified asphalt has been improved. [ABSTRACT FROM AUTHOR]

To improve the low-temperature performance of the Buton rock asphalt (BRA)-modified asphalt, styrene-butadiene rubber (SBR) was added to it. The BRA-modified asphalt and SBR-BRA composite modified asphalt were prepared by high-speed shearing method. The penetration, softening point, ductility, and Brookfield viscosity of the two kinds of asphalt were measured. The dynamic shear rheometer (DSR) and the beam bending rheometer (BBR) were employed to research the performance of BRA-modified asphalt by adding SBR. The results showed that the pure asphalt in BRA was the main reason to reduce the low-temperature performance of neat asphalt when the content of BRA was 19%. However, the ash in BRA was the main factor to reduce the low-temperature performance when its content was more than 39.8%. When the BRA content was 59.8%, the SBR-BRA composite modified asphalt with SBR contents of 2%, 4%, 6%, and 8%, and it shows that the penetration and ductility of the BRA-modified asphalt are increased by the addition of SBR. The equivalent brittle point was reduced, the stiffness modulus was decreased, and the creep rate was increased. At the same time, the Brookfield viscosity was reduced and the rutting factor was increased. The stiffness modulus of the SBR-BRA composite modified asphalt mixture was increased. That is to say, when SBR was mixed into the BRA-modified asphalt, the low-temperature performance could be remarkably improved based on ensuring high-temperature performance. The low-temperature index of composite modified asphalt was analyzed. It was recommended to apply the equivalent brittle point to evaluate the low-temperature performance of SBR-BRA composite modified asphalt. [ABSTRACT FROM AUTHOR]

According to the theory of molecular design, crumb rubber was grafting activated with acrylamide and then used as asphalt binder modifier. An orthogonal three-factor, three-level test was designed to optimize the preparation process of modified asphalt. Softening point, viscosity, rutting factor, ductility, stiffness modulus and creep speed index were selected as evaluation indicators to study the effects of rubber content, shear time and shear temperature by variance analysis and range analysis. The results show that the rubber content had a significant impact on the performance of modified asphalt with grafting-activated crumb rubber, while the shear temperature and shear time had little effect. The grafting activated crumb rubber content of 20%, shear temperature of 170–190 °C, and shear time of 90 min was determined as the reasonable preparation process. Modified asphalt with common crumb rubber (CRMA) and modified asphalt with grafting activated crumb rubber (A-G-R) were prepared, respectively, using the reasonable process to analyze the influence of grafting activation of crumb rubber. The results indicate that A-G-R had smaller softening point difference, lower segregation index and more stable and uniform dispersed phase. [ABSTRACT FROM AUTHOR]

• The rutting index difference of BRAAMA, AQRAAMA, and LPAB was analyzed. • The aging resistance of BRAAMA and LPAB was evaluated. • The effect of additive particle size on the high-temperature performance was studied. Rock asphalt as a green and exceptional modifier has been successfully applied in petroleum asphalt modification, but conventional research focuses on the modification of rock asphalt as a whole. In order to reveal the rock asphalt modification effect on neat asphalt from a component angle, this paper selected the common Buton rock asphalt (BRA) and Qingchuan rock asphalt (QRA) to modify neat asphalt. Firstly, the Buton rock asphalt ash modified asphalt (BRAAMA), Qingchuan rock asphalt ash modified asphalt (QRAAMA), and limestone powder asphalt binder (LPAB) were prepared. Secondly, the temperature sweep test of three materials was performed on the high-temperature behavior. The ultraviolet (UV) aging resistance of BRAAMA and LPAB was evaluated with a rutting index ratio. Finally, the high-temperature modification effects of BRA ash and limestone powder with different particle sizes on the neat asphalt were studied, respectively. The results show that the BRA ash and QRA ash significantly improved the high-temperature performance of the neat asphalt. The modification effect of BRA ash on the neat asphalt is better than that of limestone powder in terms of high-temperature behavior and aging resistance. BRA ash particle size of 200 mesh is appropriate to modify neat asphalt. The average rutting index ratio of BRAAMA to LAPB is about eight times. [ABSTRACT FROM AUTHOR]

The objectives of this research are to investigate the effect of solvent in asphalt binder, and to propose a method to determine the actual performance of asphalt binder extracted from asphalt mixture thus improving the efficiency of using RAP. The Fourier-transform infrared spectroscopy (FTIR) test was used to analyze the functional groups of trichloroethylene (TCE) and asphalt binder with TCE. This test also qualitatively and quantitatively evaluated the influence of solvent in asphalt binder. Dynamic Shear Rheometer (DSR) test was employed to measure the complex shear modulus (|G∗|) of asphalt binder with different TCE contents and to establish the relationship between the TCE contents and the |G∗| of asphalt binder. Based on the testing results, functional group = C–H of TCE can be used as an indicator to verify the existence of TCE in the extracted asphalt binder. Both band areas 834-848 cm-1 and 918-938 cm-1 changed for PG 58–28 and Pressure Aging Vessel (PAV) aged PG 58-28 binder after the addition of TCE. Band area 918-938 cm-1 can better reflect the influence of TCE in asphalt binder. Band area 834-848 cm-1 did not change when TCE content was at a low level. Both the existence of TCE and the content of TCE had a significant influence on the |G*| of unaged and PAV aged PG 58–28 asphalt binder. A regression function was built to establish the relationship between the TCE content and |G*|. With the method developed in this study, the correlation between the TCE amount and the FTIR spectrum area was quantified. The actual |G∗| of asphalt binder without TCE can be back calculated. The method used in this study provided guidance for the determination of asphalt binder performance extracted from RAP, which can be beneficial to the design of asphalt mixtures with RAP. [ABSTRACT FROM AUTHOR]

Highlights • The contacting angle of RTV/LDHs coating is 152.3°. • RTV/LDHs coating delays the freezing process of surface water droplet. • RTV/LDHs coating reduces the surface ice detachment force. • Hydrophobic and anti-icing properties of RTV/LDHs coating are durable. Abstract The formation of ice on pavement is a serious issue for driving safety. This paper proposes a new method of preparing a superhydrophobic silicone coating on asphalt pavement surfaces for the anti-icing purpose. The object of this paper is to investigate the anti-icing properties of the superhydrophobic silicone coating through the freezing time of water droplets and detachment forces of ice on asphalt mixture surfaces. In the preparation process of the coatings, an additive (layered double hydroxides, or LDHs) was initially modified by γ-methacryloxypropyltrimethoxysilane (KH550). Fourier transform infrared spectra and X-ray diffraction patterns were used to prove that LDHs particles have been successfully grafted by KH550. A special rubber (No. 107 room temperature vulcanized silicone rubber, or RTV) was then mixed with the modified LDHs to obtain the compound coating. Different amounts of solvents (No. 120 solvent naphtha) were sprayed on the compound coating to produce the micro/nano-scale rough surface. Contact angle test results show that the maximum contact angle of RTV and modified LDHs compound (RTV/LDHs) coating is 152.3° when 100 g/m2 of No. 120 solvent naphtha was sprayed on this coating. The freezing time of water droplet on the asphalt mixture with RTV/LDHs coating is 3 times longer than that on the asphalt mixture without coating. The ice detachment force on the asphalt mixture with RTV/LDHs coating decreases by 71% of that on the asphalt mixture without coatings. The vehicle traveling test displays that the RTV/LDHs coating has durable hydrophobic and anti-icing properties after the tire friction. From the above results, it can be concluded that this new superhydrophobic silicone coating makes significant improvements on the anti-icing properties of asphalt pavement. [ABSTRACT FROM AUTHOR]

• Rock asphalt modified bio-oil asphalt realizes the complementary advantages of rock asphalt as a high-temperature modifier and blends of bio-oil and old asphalt as a low-temperature performance modifier. • According to the features of blends of bio-oil and old asphalt, recycled coarse aggregate, and oil sand obtained from the separation of asphalt-aggregate, the corresponding mix design methods of recycled asphalt mixture are proposed, respectively. • The asphalt-aggregate separation technology of reclaimed asphalt pavement using bio-oil as solvent has preliminarily realized 100% reuse of RAP. Asphalt-aggregates separation of reclaimed asphalt pavement (RAP) with bio-oil as solvent is an economical, simple, and efficient method to recycle RAP materials. The byproducts of asphalt-aggregates separation of RAP are recycled aggregates and blends of bio-oil and old asphalt (BBOA). In this paper, to improve the recycling rate of BBOA and recycled aggregate after asphalt aggregate separation, Buton Rock Asphalt (BRA) is used as a high-temperature property modifier to compensate for the aging resistance and high-temperature of BBOA. The physical properties of rock asphalt modified bio-oil asphalt (RMBA) with different amounts of BBOA were studied by viscosity, frequency scanning, multiple stress creep, bending beam rheology, and aging tests. At the same time, recycled aggregates of different particle sizes and RMBA were used to prepare asphalt mixture with diverse mix design methods. The pavement properties of the recycled asphalt mixture were evaluated by rutting resistance, low-temperature bending beam, freeze–thaw splitting, and fatigue tests. The results show that RMBA realizes the complementary advantages of BRA as a high-temperature modifier and BBOA as a low-temperature performance modifier. The recommended dosage of RMBA is 20 %rock asphalt and 7 %BBOA. Under different preparation methods, the pavement performance of rock asphalt modified bio-oil asphalt mixture, asphalt mixture containing coarse recycled aggregate, and asphalt mixture containing oil sand meet the requirements of asphalt pavement design specifications, the preliminary realization of 100% recycling of RAP. [ABSTRACT FROM AUTHOR]