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The purpose of this research was to make full use of waste lubricating by-products (LBP) and reclaimed rubber powder (RR) to modify asphalt by a one-pot approach, so as to achieve the dual purpose of solving the poor storage stability of reclaimed rubber powder modified asphalt (RRMA) and the realization of solid waste recycling. A variety of characterization techniques were performed to analyze storage stability, conventional properties and microstructure of LBP-activated reclaimed rubber powder modified asphalt (Blend). Fourier transform infrared spectroscopy illustrated that not only the chemical composition of LBP was very similar to that of asphalt, but also the activation of LBP improved the compatibility of RR with asphalt and enhanced the storage stability of Blend. Fluorescence spectrum and scanning electron microscopy results indicated that the RR without LBP activation was aggregated and dispersed as blocks in asphalt, while the LBP activated RR was uniformly dispersed in the asphalt phase. The segregation test demonstrated that Blend exhibited outstanding storage stability, in which the softening point difference was within 2.5 °C and the segregation rate was −0.2–0.2. In addition, the conventional properties of Blend have been significantly improved, especially in penetration and ductility. More importantly, the short-term aging results demonstrated that, compared with RRMA, Blend possessed excellent anti-aging performance.
Peipei Kong; Gang Xu; Jingyao Yang; Xianhua Chen; Yaqin Zhu. Study on Storage Stability of Activated Reclaimed Rubber Powder Modified Asphalt. Materials 2021, 14, 4684 .
AMA StylePeipei Kong, Gang Xu, Jingyao Yang, Xianhua Chen, Yaqin Zhu. Study on Storage Stability of Activated Reclaimed Rubber Powder Modified Asphalt. Materials. 2021; 14 (16):4684.
Chicago/Turabian StylePeipei Kong; Gang Xu; Jingyao Yang; Xianhua Chen; Yaqin Zhu. 2021. "Study on Storage Stability of Activated Reclaimed Rubber Powder Modified Asphalt." Materials 14, no. 16: 4684.
The objective of the article was to enhance the recycling value of solid waste rubber by surface functionalization of desulfurized rubber powder using a one-pot method based on free-radical polymerization theory. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, scanning electron microscopy, and elemental analysis were used to characterize the maleic anhydride-grafted desulfurized rubber powder, and the grafting mechanism was also investigated. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy confirmed that maleic anhydride was grafted onto the desulfurized rubber powder. Thermogravimetric analysis indicated that the maleic anhydride-grafted desulfurized rubber powder and desulfurized rubber powder possessed different thermal properties and structure. The results of scanning electron microscopy and elemental analysis illustrated that the surface of the desulfurized rubber powder was covered with a layer of fold-like maleic anhydride polymer. The mechanism of grafting desulfurized rubber powder with maleic anhydride may be achieved by replacing the active α-H on the methylene group of the desulfurized rubber macromolecule chain.
Peipei Kong; Xianhua Chen; Gang Xu; Wei Wei. Preparation and characterization of maleic anhydride‐grafted desulfurization rubber powder by free‐radical polymerization. Polymer Engineering & Science 2021, 1 .
AMA StylePeipei Kong, Xianhua Chen, Gang Xu, Wei Wei. Preparation and characterization of maleic anhydride‐grafted desulfurization rubber powder by free‐radical polymerization. Polymer Engineering & Science. 2021; ():1.
Chicago/Turabian StylePeipei Kong; Xianhua Chen; Gang Xu; Wei Wei. 2021. "Preparation and characterization of maleic anhydride‐grafted desulfurization rubber powder by free‐radical polymerization." Polymer Engineering & Science , no. : 1.
Different aggregate gradations of asphalt concrete possess dissimilar skeleton structures, leading to diverse macroscopic and mechanical characteristics. Acoustic emission (AE) technology can realize real-time monitoring of the whole damage evolution process of materials. The objective of the present investigation was to demonstrate the fracture characteristics of asphalt concrete with three types of aggregate gradations, including dense-graded asphalt concrete (AC), stone mastic asphalt (SMA), and open-graded friction course (OGFC) under indirect tensile load on account of the acoustic emission (AE) technique. The Marshall compaction method was used to prepare specimens, and the indirect tensile test (IDT) and AE monitoring were conducted simultaneously at different temperatures. The corresponding AE parameters containing energy, cumulative energy, count, and cumulative count were adopted to characterize the fracture process of asphalt concrete with different aggregate gradations. The impact of temperature on the damage characteristics of asphalt concrete was also assessed. Test results indicated that the AE parameters could effectively classify the damage stages of asphalt concrete, and specimens with different aggregate gradations exhibited different AE characteristics during failure processes. The combination of AE parameters and cumulative AE parameters can accurately characterize the damage characteristics of asphalt concrete. SMA specimens possessed the best overall performance among these three types of asphalt concrete in terms of the variations in energy and cumulative energy at different temperatures. The findings obtained in this study can provide a practical AE-based evaluation approach for demonstrating the fracture mechanism of asphalt concrete with different aggregate gradations.
Liuxu Fu; Yubo Jiao; Xianhua Chen; Mengsu Zhang. Evaluation Approach of Fracture Behavior for Asphalt Concrete with Different Aggregate Gradations and Testing Temperatures Using Acoustic Emission Monitoring. Materials 2021, 14, 4390 .
AMA StyleLiuxu Fu, Yubo Jiao, Xianhua Chen, Mengsu Zhang. Evaluation Approach of Fracture Behavior for Asphalt Concrete with Different Aggregate Gradations and Testing Temperatures Using Acoustic Emission Monitoring. Materials. 2021; 14 (16):4390.
Chicago/Turabian StyleLiuxu Fu; Yubo Jiao; Xianhua Chen; Mengsu Zhang. 2021. "Evaluation Approach of Fracture Behavior for Asphalt Concrete with Different Aggregate Gradations and Testing Temperatures Using Acoustic Emission Monitoring." Materials 14, no. 16: 4390.
Aiming to improve the comprehensive road performance of asphalt binders, especially the high-temperature performance, a novel asphalt binder was prepared by compounding high-quality and low-cost polyethylene (PE) with graphene (GNPs) using a high-speed shearing machine. The rheological properties and interaction mechanism of PE/GNPs composite modified asphalt were investigated using temperature sweep (TeS), multiple stress creep recovery (MSCR), linear amplitude sweep (LAS) and Fourier transform infrared spectroscopy (FT-IR) and field emission scanning electron microscopy (FESEM). The experimental results demonstrated that GNPs and PE can synergistically improve the high-temperature performance of asphalt binders and enhance the rutting resistance of pavements; the pre-blended PE/GNPs masterbatch has good medium-temperature fatigue and low-temperature cracking resistance. Meanwhile, PE/GNPs dispersed uniformly in the asphalt matrix, and the microstructure and dispersion of premixed PE/GNPs masterbatch facilitated the asphalt modification. No new absorption peaks appeared in the FT-IR spectra of the composite modified asphalt, indicating that asphalt binders were physically modified with GNPs and PE. These findings may cast light on the feasibility of polyethylene/graphene composite for asphalt modification.
Huan-Yun Zhou; Huai-Bing Dou; Xian-Hua Chen. Rheological Properties of Graphene/Polyethylene Composite Modified Asphalt Binder. Materials 2021, 14, 3986 .
AMA StyleHuan-Yun Zhou, Huai-Bing Dou, Xian-Hua Chen. Rheological Properties of Graphene/Polyethylene Composite Modified Asphalt Binder. Materials. 2021; 14 (14):3986.
Chicago/Turabian StyleHuan-Yun Zhou; Huai-Bing Dou; Xian-Hua Chen. 2021. "Rheological Properties of Graphene/Polyethylene Composite Modified Asphalt Binder." Materials 14, no. 14: 3986.
With the growing interest in bituminous construction materials, desulfurized crumb rubber (CR)/styrene–butadiene–styrene (SBS) modified asphalts have been investigated by many researchers as low-cost environmental-friendly road construction materials. This study aimed to investigate the rheological properties of desulfurized CR/SBS composite modified asphalt within various temperature ranges. Bending beam rheometer (BBR), linear amplitude sweep (LAS), and multiple stress creep recovery (MSCR) tests were performed on conventional CR/SBS composite modified asphalt and five types of desulfurized CR/SBS modified asphalts. Meanwhile, Burgers’ model and the Kelvin–Voigt model were used to derive nonlinear viscoelastic parameters and analyze the viscoelastic mechanical behavior of the asphalts. The experimental results indicate that both the desulfurized CR/SBS composite modifier and force chemical reactor technique can enhance the crosslinking of CR and SBS copolymer, resulting in an improved high-, intermediate-, and low-temperature performance of desulfurized CR/SBS composite modified asphalt. Burgers’ model was found to be apposite in simulating the creep stages obtained from MSCR tests for CR/SBS composite modified asphalts. The superior high-temperature performance of desulfurized CR/SBS modified asphalt prepared with 4% SBS, 20% desulfurized rubber, and a force chemical reactor time of 45 min contributes to the good high-temperature elastic properties of the asphalt. Therefore, this combination is recommended as an optimal preparation process. In summary, the desulfurization of crumb rubber and using the force chemical reactor technique are beneficial to composite asphalt performance and can provide a new way of utilizing waste tire rubber.
Jingyao Yang; Gang Xu; Peipei Kong; Xianhua Chen. Characterization of Desulfurized Crumb Rubber/Styrene–Butadiene–Styrene Composite Modified Asphalt Based on Rheological Properties. Materials 2021, 14, 3780 .
AMA StyleJingyao Yang, Gang Xu, Peipei Kong, Xianhua Chen. Characterization of Desulfurized Crumb Rubber/Styrene–Butadiene–Styrene Composite Modified Asphalt Based on Rheological Properties. Materials. 2021; 14 (14):3780.
Chicago/Turabian StyleJingyao Yang; Gang Xu; Peipei Kong; Xianhua Chen. 2021. "Characterization of Desulfurized Crumb Rubber/Styrene–Butadiene–Styrene Composite Modified Asphalt Based on Rheological Properties." Materials 14, no. 14: 3780.
This paper aims to characterize the three-dimensional (3D) internal structure evolution of asphalt mixtures under freeze–thaw cycles. Asphalt mixtures with three levels of design void content (3%, 5%, and 7%) were prepared in the laboratory. Subsequently, X-ray computed tomography (CT) tests were conducted to capture two-dimensional (2D) images of the internal structure of samples before and after freeze–thaw testing. A set of image processing techniques for reconstructing 3D images of the internal structure were utilized to extract the internal structure properties, which were then used to analyze the changes in the air void distributions and to evaluate the internal structure evolution under freeze–thaw cycles. 3D images reconstructed from X-ray CT images illustrated a dramatic degradation in the internal structure after cyclic freeze–thaw exposure. The change in internal structure occurs mainly in three ways: (1) expansion of existing individual voids, (2) combination of two separated air voids, and (3) generation of new voids. In addition, the parametric analysis of the three-dimensional reconstructed voids revealed that the asphalt mixture void ratio increased with the number of freeze–thaw cycles, while the larger the initial void content, the more pronounced the increase in the specimens. Therefore, asphalt mixture freeze–thaw resistance should be optimized in relation to the design void content.
Gang Xu; Xianhua Chen; Xing Cai; Yunhong Yu; Jun Yang. Characterization of Three-Dimensional Internal Structure Evolution in Asphalt Mixtures during Freeze–Thaw Cycles. Applied Sciences 2021, 11, 4316 .
AMA StyleGang Xu, Xianhua Chen, Xing Cai, Yunhong Yu, Jun Yang. Characterization of Three-Dimensional Internal Structure Evolution in Asphalt Mixtures during Freeze–Thaw Cycles. Applied Sciences. 2021; 11 (9):4316.
Chicago/Turabian StyleGang Xu; Xianhua Chen; Xing Cai; Yunhong Yu; Jun Yang. 2021. "Characterization of Three-Dimensional Internal Structure Evolution in Asphalt Mixtures during Freeze–Thaw Cycles." Applied Sciences 11, no. 9: 4316.
Semi-analytical finite element method has great advantages in computational efficiency compared with three-dimensional, because it only requires a two-dimensional mesh in the cross-section by incorporating the Fourier series along the third dimension. This study utilised the method to analyse pavement responses induced by moving vehicles. Combined with the structural property of pavement, the method is improved in terms of meshing and boundary conditions based on existing research. Using the Fourier series to represent loading functions along the driving direction, the load motion can be expressed as the translation of trigonometric functions. Spring element is applied at bottom to simulate the soil support, and viscous element is applied at vertical boundary to control the interference of reflected wave. The whole algorithm was realised by MATLAB programming. This algorithm was first used to analyse a layered structure under a rectangular load. Its accuracy and efficiency were verified by comparing it with a three-dimensional finite element model in ABAQUS. Then this algorithm was utilised to simulate a test road under a moving truck. The material assembly used the parameters calibrated by several nondestructive tests. Analysis results were compared with the field monitor of sensors for verification. This study also has some reference value about applying semi-analytical finite element method in pavement engineering.
Kairen Shen; Hanyu Zhang; Jusheng Tong; Hao Wang; Xianhua Chen. Dynamic elastic analysis of flexible pavements under moving vehicles: a semi-analytical finite element treatment. Road Materials and Pavement Design 2021, 1 -11.
AMA StyleKairen Shen, Hanyu Zhang, Jusheng Tong, Hao Wang, Xianhua Chen. Dynamic elastic analysis of flexible pavements under moving vehicles: a semi-analytical finite element treatment. Road Materials and Pavement Design. 2021; ():1-11.
Chicago/Turabian StyleKairen Shen; Hanyu Zhang; Jusheng Tong; Hao Wang; Xianhua Chen. 2021. "Dynamic elastic analysis of flexible pavements under moving vehicles: a semi-analytical finite element treatment." Road Materials and Pavement Design , no. : 1-11.
Analyzing dynamic viscoelastic responses induced by moving loads is a significant issue for pavement design and performance evaluation. Developing three-dimensional FE models in commercial software is an effective method, but the time-consuming disadvantage prevents it from extensive engineering applications. In this paper, an improved semi-analytical FE model was proposed to overcome this drawback. Besides, modified artificial boundaries were applied to minimise the interference of reflected waves generated by model edges. Further, a program named SAPAVE has been developed in MATLAB to achieve the modeling procedure, of which accuracy and efficiency were verified by comparing with the three-dimensional FE model in ABAQUS. The computing cost of SAPAVE was only one-sixth of ABAQUS, while SAPAVE can roughly achieve the function of ABAQUS for simple pavement modeling. The response considering the asphalt layer as viscoelastic was quite different from the linear elastic in the comparative study. The viscoelastic analysis seems to be closer to the field situation. Besides, the impact of vehicle speed was studied to examine the application ability of SAPAVE, and the results were generally consistent with existing researches. Overall, this study indicates that SAPAVE is an efficient and accurate tool for mechanical analysis of asphalt pavement.
Kairen Shen; Hao Wang; Hanyu Zhang; Jusheng Tong; Xianhua Chen. SAPAVE: an improved semi-analytical FE program for dynamic viscoelastic analysis of asphalt pavement. International Journal of Pavement Engineering 2021, 1 -12.
AMA StyleKairen Shen, Hao Wang, Hanyu Zhang, Jusheng Tong, Xianhua Chen. SAPAVE: an improved semi-analytical FE program for dynamic viscoelastic analysis of asphalt pavement. International Journal of Pavement Engineering. 2021; ():1-12.
Chicago/Turabian StyleKairen Shen; Hao Wang; Hanyu Zhang; Jusheng Tong; Xianhua Chen. 2021. "SAPAVE: an improved semi-analytical FE program for dynamic viscoelastic analysis of asphalt pavement." International Journal of Pavement Engineering , no. : 1-12.
To obtain the water distribution influenced by pavement alignment design under the current situation of highway reconstruction and extension in China, a simulation model for predicting pavement flow fields and water depth distribution is optimized based on a hydrodynamic method. Two-dimensional shallow water equations were applied to investigate the pavement water by considering the factors of rainfall, topography, and fluid resistance. This model was validated by the field monitoring data and the measured depth and velocity. Pavement terrain models were performed to analyze the water depth distribution of the straight and superelevation, and specifically, the inundation areas and the depth difference of the same lane at the transition are compared. Results show that the water depths are influenced by the pavement widths. Water depth distribution on the cross section of zero cross slope (ZCS) and the range of the inundation areas increase as the pavement broadens. Besides the distribution of submerging areas, the depth difference between wheel traces also should be considered for evaluating driving safety.
Yaolu Ma; Yanfen Geng; Xianhua Chen. Water Distribution Influenced by Pavement Alignment Design. Journal of Transportation Engineering, Part B: Pavements 2020, 146, 04020058 .
AMA StyleYaolu Ma, Yanfen Geng, Xianhua Chen. Water Distribution Influenced by Pavement Alignment Design. Journal of Transportation Engineering, Part B: Pavements. 2020; 146 (4):04020058.
Chicago/Turabian StyleYaolu Ma; Yanfen Geng; Xianhua Chen. 2020. "Water Distribution Influenced by Pavement Alignment Design." Journal of Transportation Engineering, Part B: Pavements 146, no. 4: 04020058.
While as a jointless cementitious asphalt material, semi-flexible pavement material (SFP) behaves well in rutting resistance, cracking has been a major barrier in its application promotion. Although many material modifications have been proved effective to improve SFP’s performance to some degree, it is still unclear what the crack mechanism is and whether it is similar in asphalt concrete until now. Thus, splitting test was conducted on SFP at three different temperatures (−10 °C, 10 °C and 25 °C) to investigate SFP’s damage process. Acoustic Emission (AE) technique was employed at the same time to collect signals from various of damage sources. An unsupervised method, k-means, was used to classify AE data. The X-ray scanning images of the samples after fracture were observed to assist in cluster identification, together with the images of the fracture cross sections. Three damage mechanism clusters were identified as skeletal aggregate moving friction, together with cement cracking, asphalt cohesive damage and debonding. The result reveals that SFP cracks more easily at 25 °C. There is a temperature effect in the damage process of SFP: the damage mode shifts from main macro-crack to distributed meso-cracks, as well as from interface debonding, aggregate cracking to asphalt/cement damage. Besides, the absolute energy development of each cluster indicates that damage in cement caused by uncoordinated deformation contributes much to capability loss in SFP at 25 °C.
Xing Cai; Chenguang Shi; Xianhua Chen; Jun Yang. Identification of damage mechanisms during splitting test on SFP at different temperatures based on acoustic emission. Construction and Building Materials 2020, 270, 121391 .
AMA StyleXing Cai, Chenguang Shi, Xianhua Chen, Jun Yang. Identification of damage mechanisms during splitting test on SFP at different temperatures based on acoustic emission. Construction and Building Materials. 2020; 270 ():121391.
Chicago/Turabian StyleXing Cai; Chenguang Shi; Xianhua Chen; Jun Yang. 2020. "Identification of damage mechanisms during splitting test on SFP at different temperatures based on acoustic emission." Construction and Building Materials 270, no. : 121391.
Asphalt concrete paved on the surface of a roadbed as a ballastless track substructure has an excellent waterproofing and vibration attenuation performance. However, the mechanical characteristics and the failure mode of this structure under the actions of a cyclic train load and ambient air temperature changes are still unclear. Therefore, a test section of an asphalt concrete substructure was constructed based on a high-speed railway ballastless track project in north China. In situ forced vibration tests and temperature-induced deformation monitoring tests were performed to investigate the mechanical responses of the asphalt concrete, respectively. Test results show that the bottom of the asphalt concrete layer is in the tensile state under the action of the cyclic train load. The surface of the asphalt concrete in contact with the base plate is subjected to tensile stress near the expansion joint under the action of the negative temperature gradient. Changes in the ambient temperature lead to more significant mechanical responses of the asphalt concrete substructure than the cyclic train load, especially near the expansion joint of the base plate. Therefore, the passive tensile failure mode may occur near the expansion joint of the base plate. However, it has also proved that setting isolation layers under the base plate near the expansion joint is an effective method to significantly reduce responses near the expansion joint in this research.
Qinghong Fu; Xianhua Chen; DeGou Cai; Liangwei Lou. Mechanical Characteristics and Failure Mode of Asphalt Concrete for Ballastless Track Substructure Based on In Situ Tests. Applied Sciences 2020, 10, 3547 .
AMA StyleQinghong Fu, Xianhua Chen, DeGou Cai, Liangwei Lou. Mechanical Characteristics and Failure Mode of Asphalt Concrete for Ballastless Track Substructure Based on In Situ Tests. Applied Sciences. 2020; 10 (10):3547.
Chicago/Turabian StyleQinghong Fu; Xianhua Chen; DeGou Cai; Liangwei Lou. 2020. "Mechanical Characteristics and Failure Mode of Asphalt Concrete for Ballastless Track Substructure Based on In Situ Tests." Applied Sciences 10, no. 10: 3547.
The interfacial bond between cement concrete base plate (CCBP) and asphalt concrete waterproofing layer (ACWL) is a weak portion in the newly developed Chinese high-speed railway ballastless track. The interface damage caused due to fluctuating temperature load and dynamic train load is one of the most critical problems in Northern China. This paper aims to investigate the interface damage evolution process under temperature load via experimental and simulation analysis. Full-scale transverse shear tests were performed to explore the interface bond-slip mode of the adjacent ACWL and CCBP. Then, a finite element model of a ballastless track structure was built and a cohesive zone model (CZM) was utilized to model the interface damage initiation, crack propagation, and delamination process under uniform/gradient temperature load. Furthermore, the dynamic response of the ballastless track where CCBP and ACWL were partly/totally debonded was investigated and compared with the perfectly bonded structure. The results demonstrate that bilinear CZM is capable of revealing the interface damage initiation, crack propagation, and delamination process under temperature load. The interface state between the adjacent CCBP and ACWL was greatly affected by temperature changes and the interface bonding state had a great impact on the dynamic response of ballastless track.
Xianhua Chen; Yu Zhu; DeGou Cai; Gang Xu; Tao Dong. Investigation on Interface Damage between Cement Concrete Base Plate and Asphalt Concrete Waterproofing Layer under Temperature Load in Ballastless Track. Applied Sciences 2020, 10, 2654 .
AMA StyleXianhua Chen, Yu Zhu, DeGou Cai, Gang Xu, Tao Dong. Investigation on Interface Damage between Cement Concrete Base Plate and Asphalt Concrete Waterproofing Layer under Temperature Load in Ballastless Track. Applied Sciences. 2020; 10 (8):2654.
Chicago/Turabian StyleXianhua Chen; Yu Zhu; DeGou Cai; Gang Xu; Tao Dong. 2020. "Investigation on Interface Damage between Cement Concrete Base Plate and Asphalt Concrete Waterproofing Layer under Temperature Load in Ballastless Track." Applied Sciences 10, no. 8: 2654.
The purpose of this paper is to report on the drainage of porous asphalt pavement evaluation method suited for use in analyzing clogging effect. To preliminarily reveal the decrease in permeability caused by clogging of permeable asphalt pavement, an innovative device was proposed to evaluate the anisotropy of permeability influenced by clogging, and the maximum drainage capacity without surface ponding can be obtained when the supplied water was controlled. Then, finite element models for asphalt pavements with hydromechanical coupling were proposed based on porous media theory and Biot’s theory. The variation in pore water pressure was simulated by considering the decrease in voids and the increase in clogging grains. The results indicate that the internally retained water should not be ignored because the semiconnected voids were filled with water rapidly at the beginning of permeability tests. To avoid surface ponding, the drainage capacity coefficient (DCC) can be used to evaluate the maximum drainage capacity (MDC) influenced by clogging. Moreover, the pore water pressure increased due to the reduction in voids and a high level of clogging. In addition, the peak value of pore water pressure is also affected by the upper-layer height of the pavement. Under the action of clogging and driving load, a reasonable thickness of the upper layer and a drainage evaluation should be considered to improve road safety.
Yaolu Ma; Xianhua Chen; Yanfen Geng; Xinlan Zhang. Effect of Clogging on the Permeability of Porous Asphalt Pavement. Advances in Materials Science and Engineering 2020, 2020, 1 -9.
AMA StyleYaolu Ma, Xianhua Chen, Yanfen Geng, Xinlan Zhang. Effect of Clogging on the Permeability of Porous Asphalt Pavement. Advances in Materials Science and Engineering. 2020; 2020 ():1-9.
Chicago/Turabian StyleYaolu Ma; Xianhua Chen; Yanfen Geng; Xinlan Zhang. 2020. "Effect of Clogging on the Permeability of Porous Asphalt Pavement." Advances in Materials Science and Engineering 2020, no. : 1-9.
This paper summarizes the results of laboratory tests including scanning electron microscopy (SEM), X-ray computed tomography (CT), a developed interfacial shear test and the indirect tensile test. These tests were performed to characterize the damage of dense-graded asphalt mixture under freeze-thaw cycles from different length scales. SEM was utilized to observe the surface of asphalt mixture samples and showed that micro-cracks occurred at the contact interface between asphalt and aggregate after cyclic freeze-thaw exposure, indicating the loss of adhesion bonds at the aggregate-mastic interface. Meanwhile, X-ray CT and a set of image processing techniques were employed to capture the evolution of three-dimensional internal structure within samples under freeze-thaw cycles from a mesoscopic-view. Three-dimensional images reconstructed from X-ray CT images illustrated that the diversification in internal structure was observed to occur mainly in three ways: (1) expansion of existing individual voids, (2) combination of two separated air voids, and (3) generation of new voids. Furthermore, a developed interfacial shear test was conducted to quantify shear bond properties between asphalt and aggregate, which revealed that the interfacial shear strength decreases with the increase of the number of freeze-thaw cycles and declines rapidly at the initial stage of freeze-thaw cycles. Finally, the indirect tensile test (IDT) was applied to evaluate the loss of tensile strength within the samples on a macro-scale. The evolution of IDT strength consisted with the variations of mesoscopic parameters such as interfacial shear strength, three-dimensional void content and void number, and then a systematic evaluation of moisture damage of asphalt mixture could be done.
Gang Xu; Yunhong Yu; DeGou Cai; Guanyu Xie; Xianhua Chen; Jun Yang. Multi-scale damage characterization of asphalt mixture subject to freeze-thaw cycles. Construction and Building Materials 2020, 240, 117947 .
AMA StyleGang Xu, Yunhong Yu, DeGou Cai, Guanyu Xie, Xianhua Chen, Jun Yang. Multi-scale damage characterization of asphalt mixture subject to freeze-thaw cycles. Construction and Building Materials. 2020; 240 ():117947.
Chicago/Turabian StyleGang Xu; Yunhong Yu; DeGou Cai; Guanyu Xie; Xianhua Chen; Jun Yang. 2020. "Multi-scale damage characterization of asphalt mixture subject to freeze-thaw cycles." Construction and Building Materials 240, no. : 117947.
This paper aims to investigate the fatigue resistance of asphalt binders using different analytical methods and fatigue failure criteria with the consideration of various aging conditions. Four different performance grade (PG) binders with and without modifiers were tested by Linear Amplitude Sweep (LAS) test to characterize their fatigue behavior. The fatigue failure strain was determined using three different definitions: peak value of shear stress, peak value of phase angle and the maximum stored pseudo-strain energy. The damage characteristic curves and fatigue life were obtained by two kinds of analytical methods: dissipated energy-based method and pseudo-strain energy-based method. Statistical analysis shows that there is no distinct difference between these three criteria of fatigue failure for aged and unaged asphalt binders. However, for the modified asphalt binders at unaged condition, it is hard to observe the peak value of phase angle or stored pseudo-strain energy. The fatigue life determined by the pseudo-strain energy-based method is slightly higher than that of dissipated energy-based method across the entire loading strain range. In addition, the fatigue resistance of neat asphalt binder tested in this paper is deteriorated at high strain levels but improved at low strain levels and the critical strain level is approximate 4.5%. The effect of aging is asphalt specific and depends on the strain levels from the experimental results.
Hanyu Zhang; Kairen Shen; Gang Xu; Jusheng Tong; Rui Wang; DeGou Cai; Xianhua Chen. Fatigue resistance of aged asphalt binders: An investigation of different analytical methods in linear amplitude sweep test. Construction and Building Materials 2020, 241, 118099 .
AMA StyleHanyu Zhang, Kairen Shen, Gang Xu, Jusheng Tong, Rui Wang, DeGou Cai, Xianhua Chen. Fatigue resistance of aged asphalt binders: An investigation of different analytical methods in linear amplitude sweep test. Construction and Building Materials. 2020; 241 ():118099.
Chicago/Turabian StyleHanyu Zhang; Kairen Shen; Gang Xu; Jusheng Tong; Rui Wang; DeGou Cai; Xianhua Chen. 2020. "Fatigue resistance of aged asphalt binders: An investigation of different analytical methods in linear amplitude sweep test." Construction and Building Materials 241, no. : 118099.
Semi-flexible pavement (SFP) material has been promoted to apply in pavement engineering mainly for its excellent performance in rutting resistance. But its mechanical behavior is complicated due to its heterogeneity and interlocking structure. According to the present study, the damage process of SFP (with and without fiber), as well as its porous asphalt (PA) matrix, under uniaxial compression test was detected employing acoustic emission (AE) technique. The heterogeneity and the interlocking effect were varied by changing the matrix porosity and the gradation, respectively. The stress-strain curves reveal that cement grouting could decrease the material’s failure strain distinctly, while the addition of fiber made no effect on the results. Nevertheless, both the cement grouting and the addition of fiber caused medium and high amplitude (50–65 dB) AE signals during the AE detection. Besides, the Rise Angle (RA) value and energy distribution both illustrate that there was increasing trend in the amounts of shear cracking in SFP during compression, which was different from asphalt mixtures. And the addition of fiber could restrain the shear cracking to improve the crack resistance. Quantificationally, heterogeneity was characterized by standard deviation of compositions’ modulus and an interlocking index was extracted from a modulus micromechanical model to characterize the interlocking effect. The Weibull distribution was adopted to characterize the damage evolution, where the cumulative AE energy was chosen as the damage variable. The result shows the two Weibull parameters m, n had obviously positive correlation with the matrix porosity and the interlocking index, respectively.
Xing Cai; Liuxu Fu; Jiayun Zhang; Xianhua Chen; Jun Yang. Damage analysis of semi-flexible pavement material under axial compression test based on acoustic emission technique. Construction and Building Materials 2019, 239, 117773 .
AMA StyleXing Cai, Liuxu Fu, Jiayun Zhang, Xianhua Chen, Jun Yang. Damage analysis of semi-flexible pavement material under axial compression test based on acoustic emission technique. Construction and Building Materials. 2019; 239 ():117773.
Chicago/Turabian StyleXing Cai; Liuxu Fu; Jiayun Zhang; Xianhua Chen; Jun Yang. 2019. "Damage analysis of semi-flexible pavement material under axial compression test based on acoustic emission technique." Construction and Building Materials 239, no. : 117773.
In this study, a new type of composite modified bitumen was developed by blending styrene-butadiene-styrene (SBS) and crumb rubber (CR) with a chemical method to satisfy the durability requirements of waterproofing material in the waterproofing layer of high-speed railway subgrade. A pressure-aging-vessel test for 20, 40 and 80 h were conducted to obtain bitumen samples in different long-term aging conditions. Multiple stress creep recovery (MSCR) tests, linear amplitude scanning tests and bending beam rheometer tests were conducted on three kinds of asphalt binders (SBS modified asphalt, CR modified asphalt and SBS/CR composite modified asphalt) after different long-term aging processes, including high temperature permanent deformation performance, resistance to low temperature thermal and fatigue crack. Meanwhile, aging sensitivities were compared by different rheological indices. Results showed that SBS/CR composite modified asphalt possessed the best properties before and after aging. The elastic property of CR in SBS/CR composite modified asphalt improved the ability to resist low temperature thermal and fatigue cracks at a range of low and middle temperatures. Simultaneously, the copolymer network of SBS and CR significantly improved the elastic response of the asphalt SBS/CR modified asphalt at a range of high temperatures. Furthermore, all test results indicated that the SBS/CR modified asphalt possesses the outstanding ability to anti-aging. SBS/CR is an ideal kind of asphalt to satisfy the demand of 60 years of service life in the subgrade of high speed railway.
Yangsheng Ye; Gang Xu; Liangwei Lou; Xianhua Chen; DeGou Cai; Yuefeng Shi. Evolution of Rheological Behaviors of Styrene-Butadiene-Styrene/Crumb Rubber Composite Modified Bitumen after Different Long-Term Aging Processes. Materials 2019, 12, 2345 .
AMA StyleYangsheng Ye, Gang Xu, Liangwei Lou, Xianhua Chen, DeGou Cai, Yuefeng Shi. Evolution of Rheological Behaviors of Styrene-Butadiene-Styrene/Crumb Rubber Composite Modified Bitumen after Different Long-Term Aging Processes. Materials. 2019; 12 (15):2345.
Chicago/Turabian StyleYangsheng Ye; Gang Xu; Liangwei Lou; Xianhua Chen; DeGou Cai; Yuefeng Shi. 2019. "Evolution of Rheological Behaviors of Styrene-Butadiene-Styrene/Crumb Rubber Composite Modified Bitumen after Different Long-Term Aging Processes." Materials 12, no. 15: 2345.
The preponderances of different modifiers in terms of performance improvement are polymerized in compound modified asphalt. However, limitation still exists in the appropriate evaluation of aging resistance of compound modified asphalt, due to the inevitable aging behavior of asphalt and the various effects of aging on different modifiers. The objective of this paper was to explore reasonable aging resistance evaluation methods for compound modified asphalt. A new type of compound modified asphalt – high-performance crumb tire rubber compound modified asphalt (HR) was concerned and compared with basic SBS modified asphalt and high viscosity compound modified asphalt (HV) under the same conditions. Rotating thin film oven test (RTFOT) and pressure aging vessel (PAV) test were applied to simulate short-term and long-term aging, respectively. Rheological performances of three kinds of asphalt under different aging conditions were systematically tested in the whole temperature domain, including bending beam rheometer test (BBR), multiple stress creep recovery test (MSCR), Brookfield viscosity test (RV), and linear amplitude sweep test (LAS). A new aging index C*AI based on fatigue damage theory was established, and the evaluation effectiveness of other aging indexes on the aging resistance of compound modified asphalt was compared and analyzed. The results showed that different performances of compound modified asphalt have various sensitivity to aging, but in general, HR shows the best aging resistance performance among the three kinds of asphalt. Based on the comparison of different aging indexes, the aging index C*AI can effectively evaluate the aging resistance of compound modified asphalt.
Rui Wang; Gang Xu; Xianhua Chen; Wenbin Zhou; Hanyu Zhang. Evaluation of aging resistance for high-performance crumb tire rubber compound modified asphalt. Construction and Building Materials 2019, 218, 497 -505.
AMA StyleRui Wang, Gang Xu, Xianhua Chen, Wenbin Zhou, Hanyu Zhang. Evaluation of aging resistance for high-performance crumb tire rubber compound modified asphalt. Construction and Building Materials. 2019; 218 ():497-505.
Chicago/Turabian StyleRui Wang; Gang Xu; Xianhua Chen; Wenbin Zhou; Hanyu Zhang. 2019. "Evaluation of aging resistance for high-performance crumb tire rubber compound modified asphalt." Construction and Building Materials 218, no. : 497-505.
A type of styrene-butadiene-styrene (SBS) and crumb rubber (CR) composite modified asphalt (CMA) binder with a chemical (-C) method was proposed in this research. Dynamic shear rheometer (DSR) tests were conducted at different frequency and temperature to evaluate rheological properties of SBS/CR-C CMA in different aging conditions. Rheological master curves were also constructed to survey its rheological properties in a broad range of frequencies and temperatures. Based on test results, it was concluded that the rheology of SBS/CR-C CMA prepared by ultra-fine embedding grafting technology has been improved over a wide temperature range, showing good high and low temperature properties. In the low temperature domain, the asphalt provides good fatigue resistance attributed to the elastic property of CR. And in the high temperature domain, the copolymer network significantly improves the elastic response of SBS/CR-C CMA, showing better deformation recovery. In addition, short- and long-term aging enhance the shear deformation resistance and elastic behavior of SBS/CR-C CMA, but weaken the low-temperature cracking and fatigue resistance performance. SBS/CR-C CMA has excellent anti-aging property.
Qinghong Fu; Gang Xu; Xianhua Chen; Jie Zhou; Fengmin Sun. Rheological properties of SBS/CR-C composite modified asphalt binders in different aging conditions. Construction and Building Materials 2019, 215, 1 -8.
AMA StyleQinghong Fu, Gang Xu, Xianhua Chen, Jie Zhou, Fengmin Sun. Rheological properties of SBS/CR-C composite modified asphalt binders in different aging conditions. Construction and Building Materials. 2019; 215 ():1-8.
Chicago/Turabian StyleQinghong Fu; Gang Xu; Xianhua Chen; Jie Zhou; Fengmin Sun. 2019. "Rheological properties of SBS/CR-C composite modified asphalt binders in different aging conditions." Construction and Building Materials 215, no. : 1-8.
The paper investigated the low temperature performance of asphalt binders modified by SBS, SBS/crumb rubber (CR) and SBS/TAFPACK-Super (TPS). The bending beam rheometer (BBR) test was utilized to compare the rheological properties of three modified asphalt binders at low temperatures. Firstly, the low service temperature of three asphalt binders was calculated from the BBR test results according to the Performance Grading (PG) protocol. Secondly, the generalized fractional viscoelastic model was introduced to construct the master curve of the flexural creep stiffness based on the time-temperature superposition principle. Then the property of three asphalt binders at low temperatures was compared by three approaches based on the generalized fractional model, including the graph of master curve, the derivation of creep compliance and dissipated energy ratio. The comparison results of different indicators showed that the SBS/CR compound modified asphalt had the best low temperature performance followed by the SBS/TPS asphalt and SBS asphalt. Additionally, the strain energy density of three-point bending test and the fracture temperature of thermal stress restrained specimen test (TSRST) for asphalt mixtures further proved the superiority of low temperature crack resistance of SBS/CR compound modified asphalt mixtures. Finally, the results of grey rational analysis demonstrated that the dissipated energy ratio of asphalt binders had a good correlation with the low temperature performance of asphalt mixtures. The study indicates that the SBS/CR compound modified asphalt binder could better meet the demands of pavement materials in cold regions.
Jie Zhou; Xianhua Chen; Gang Xu; Qinghong Fu. Evaluation of low temperature performance for SBS/CR compound modified asphalt binders based on fractional viscoelastic model. Construction and Building Materials 2019, 214, 326 -336.
AMA StyleJie Zhou, Xianhua Chen, Gang Xu, Qinghong Fu. Evaluation of low temperature performance for SBS/CR compound modified asphalt binders based on fractional viscoelastic model. Construction and Building Materials. 2019; 214 ():326-336.
Chicago/Turabian StyleJie Zhou; Xianhua Chen; Gang Xu; Qinghong Fu. 2019. "Evaluation of low temperature performance for SBS/CR compound modified asphalt binders based on fractional viscoelastic model." Construction and Building Materials 214, no. : 326-336.