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In order to reveal the effect of complex stress state on the characteristics of strength and stiffness of asphalt mixture, the self-developed double confining pressure triaxial test method was used in this study. The one-time failure and resilient modulus tests in complex stress state were carried out on the SMA-13 and AC-13 asphalt mixtures widely used in China's asphalt pavement, especially in the combined tensile-compressive stress state. The failure principal stress of material and its stress-strain data under the step loading condition were obtained. The calculation model of resilient modulus in complex stress state and the failure criterion I1-J2 in the principal stress space were established. On this basis, based on the generalized Hooke's law, a three-dimensional strain failure criterion model for asphalt mixture considering the effect of stiffness was also established by the conversion method. The research results can provide experimental and theoretical support for the reasonable selection and resistance calculation of material parameters of asphalt mixture in complex stress state.
Tuo Huang; Jie Chen; Mi Li; Yao Tang; Songtao Lv; Huanan Yu; Hongfu Liu; Wei Yan. Investigation on three-dimensional failure criterion of asphalt mixture considering the effect of stiffness. Construction and Building Materials 2021, 285, 122431 .
AMA StyleTuo Huang, Jie Chen, Mi Li, Yao Tang, Songtao Lv, Huanan Yu, Hongfu Liu, Wei Yan. Investigation on three-dimensional failure criterion of asphalt mixture considering the effect of stiffness. Construction and Building Materials. 2021; 285 ():122431.
Chicago/Turabian StyleTuo Huang; Jie Chen; Mi Li; Yao Tang; Songtao Lv; Huanan Yu; Hongfu Liu; Wei Yan. 2021. "Investigation on three-dimensional failure criterion of asphalt mixture considering the effect of stiffness." Construction and Building Materials 285, no. : 122431.
The authors wish to make the following correction to this paper
Chengdong Xia; Songtao Lv; Lingyun You; Dong Chen; Yipeng Li; Jianlong Zheng. Correction: Xia, C.; et al. Unified Strength Model of Asphalt Mixture under Various Loading Modes. Materials 2019, 12, 889. Materials 2020, 13, 5393 .
AMA StyleChengdong Xia, Songtao Lv, Lingyun You, Dong Chen, Yipeng Li, Jianlong Zheng. Correction: Xia, C.; et al. Unified Strength Model of Asphalt Mixture under Various Loading Modes. Materials 2019, 12, 889. Materials. 2020; 13 (23):5393.
Chicago/Turabian StyleChengdong Xia; Songtao Lv; Lingyun You; Dong Chen; Yipeng Li; Jianlong Zheng. 2020. "Correction: Xia, C.; et al. Unified Strength Model of Asphalt Mixture under Various Loading Modes. Materials 2019, 12, 889." Materials 13, no. 23: 5393.
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.
Guoqing Wang; Xinqiang Wang; Songtao Lv; Lusheng Qin; Xinghai Peng. Laboratory Investigation of Rubberized Asphalt Using High-Content Rubber Powder. Materials 2020, 13, 4437 .
AMA StyleGuoqing Wang, Xinqiang Wang, Songtao Lv, Lusheng Qin, Xinghai Peng. Laboratory Investigation of Rubberized Asphalt Using High-Content Rubber Powder. Materials. 2020; 13 (19):4437.
Chicago/Turabian StyleGuoqing Wang; Xinqiang Wang; Songtao Lv; Lusheng Qin; Xinghai Peng. 2020. "Laboratory Investigation of Rubberized Asphalt Using High-Content Rubber Powder." Materials 13, no. 19: 4437.
The most common primary damage form of rubber asphalt pavements is fatigue cracking. At present, the indirect tension, direct tension, bending, and unconfined compression tests are the main considered fatigue parameters to design the structure of rubber asphalt pavement. However, the fatigue test results analyzed by various test methods have a quite significant divergence, which represents a lack of accuracy to access the durability of rubber asphalt mixture objectively. Thus, in the structural resistance design of rubber asphalt pavement, there exists a problem of artificial randomness of fatigue parameters. Hence, the primary objective of this study is to improve the procedure for determining the structural resistance of rubber asphalt pavement. To this end, the direct tensile, unconfined compressive, and indirect tensile strength tests of rubber asphalt mixture were performed under various loading rates to reveal the velocity-dependent of the strength of rubber asphalt mixture. The model of direct tensile strength, unconfined compressive strength, and indirect tensile strength increasing with loading rate are SD=7.772v0.205, SC=1.748v0.204, and ST=1.077v0.207, respectively. The stress ratio related to both the traditional S-N fatigue equation and the loading rate was defined as the standard stress ratio and the velocity-dependent stress ratio, respectively. The fatigue test of rubber asphalt mixture was conducted. The results from those experiments were analyzed. A fatigue equation (Nf=tv-5.129 R2=0.853) related to the loading rate was established. The results indicated that the viscoelastic characteristics of rubber asphalt mixture are not taken into consideration in the traditional S-N fatigue equation, which contributed to the non-uniqueness and uncertainty of fatigue test results. The viscoelastic characteristics of rubber asphalt mixture are considered by the fatigue equation related to the velocity-dependent stress ratio. Thus, a new method (Kv=Nf0.0958) considering the influence of the loading rate for calculating the strength structure coefficient of the rubber asphalt mixture was proposed. The effectiveness and completeness of the mechanical behavior of pavement structure characterized by material parameters were improved. Thus, the utilization rate of waste rubber for pavement construction can be significantly increased and the life cycle cost of asphalt pavement is reduced.
Chengdong Xia; Songtao Lv; Milkos Borges Cabrera; Xiaofeng Wang; Chao Zhang; Lingyun You. Unified characterizing fatigue performance of rubberized asphalt mixtures subjected to different loading modes. Journal of Cleaner Production 2020, 279, 123740 .
AMA StyleChengdong Xia, Songtao Lv, Milkos Borges Cabrera, Xiaofeng Wang, Chao Zhang, Lingyun You. Unified characterizing fatigue performance of rubberized asphalt mixtures subjected to different loading modes. Journal of Cleaner Production. 2020; 279 ():123740.
Chicago/Turabian StyleChengdong Xia; Songtao Lv; Milkos Borges Cabrera; Xiaofeng Wang; Chao Zhang; Lingyun You. 2020. "Unified characterizing fatigue performance of rubberized asphalt mixtures subjected to different loading modes." Journal of Cleaner Production 279, no. : 123740.
Strength and fatigue life are essential parameters of pavement structure design. To accurately determine the pavement structure resistance of rubber asphalt mixture, the strength tests at various temperatures, loading rate, and fatigue tests at different stress levels were conducted in this research. Based on the proposed experiments, the change law of rubber asphalt mixture strength with different temperatures and loading rates was revealed. The phenomenological fatigue equation of rubber asphalt mixture was established. The genetic algorithm optimized backpropagation neural network (GA-BPNN) is highly reliable for optimizing production processes in civil engineering, and it has a remarkable application effect. A GA-BPNN strength and fatigue life prediction model was created in this study. The reliability of the prediction model was verified through experiments. The results showed that the rubber asphalt mixture strength decreases and increases with the increase of temperature and loading rate, respectively. The goodness of fit of the rubber asphalt mixture strength and fatigue life prediction model based on the GA-BPNN could reach 0.989 and 0.998, respectively. The indicators of the fatigue life prediction model are superior to the conventional phenomenological fatigue equation model. The GA-BPNN provides an effective method for predicting the rubber asphalt mixture strength and fatigue life, which significantly improves the accuracy of the resistance design of the rubber asphalt pavement structure.
Jiang Yuan; Songtao Lv; Xinghai Peng; Lingyun You; Milkos Borges Cabrera. Investigation of Strength and Fatigue Life of Rubber Asphalt Mixture. Materials 2020, 13, 3325 .
AMA StyleJiang Yuan, Songtao Lv, Xinghai Peng, Lingyun You, Milkos Borges Cabrera. Investigation of Strength and Fatigue Life of Rubber Asphalt Mixture. Materials. 2020; 13 (15):3325.
Chicago/Turabian StyleJiang Yuan; Songtao Lv; Xinghai Peng; Lingyun You; Milkos Borges Cabrera. 2020. "Investigation of Strength and Fatigue Life of Rubber Asphalt Mixture." Materials 13, no. 15: 3325.
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.
Fangting Qu; Songtao Lv; Junfeng Gao; Chaochao Liu. Performance and Mechanism of Asphalt Modified by Buton-Rock Asphalt and Different Types of Styrene-Butadiene-Rubber. Applied Sciences 2020, 10, 3077 .
AMA StyleFangting Qu, Songtao Lv, Junfeng Gao, Chaochao Liu. Performance and Mechanism of Asphalt Modified by Buton-Rock Asphalt and Different Types of Styrene-Butadiene-Rubber. Applied Sciences. 2020; 10 (9):3077.
Chicago/Turabian StyleFangting Qu; Songtao Lv; Junfeng Gao; Chaochao Liu. 2020. "Performance and Mechanism of Asphalt Modified by Buton-Rock Asphalt and Different Types of Styrene-Butadiene-Rubber." Applied Sciences 10, no. 9: 3077.
The molecular model of asphalt binder was established by means of molecular dynamics (MD). The MD model was validated with respect of density, glass transition temperature, viscosity and solubility parameters. An interface system was created by inserting a vacuum pad of 50 Å between 2 groups of asphalt binders to study the self-healing behavior of the asphalt binder, e.g. internal volume, diffusion rate of each component and energy variation of the model. The molecular diffusion of aged asphalt binder, SBS modified asphalt binder, and virgin asphalt binder are studied. The results show that the “compression” of asphalt binder volume and the “stretching” of the asphalt binder molecules is responsible for the disappearance of vacuum micro-cracks inside the asphalt binder. When the model volume is “compressed”, the volume of the asphalt model decreases until the micro-cracks in the asphalt binder disappear completely. The molecular volume of asphalt decreases greatly at the beginning of the MD simulation, and then becomes stable. The length of asphalt model increases in the OZ direction, while the length of the OX and OY directions decreases, indicating that asphalt “stretces” during the self-healing process. During the self-healing process, the diffusion coefficient of asphaltene molecule is the lowest, while the diffusion coefficient of the saturates is the highest at 360 K, aromatics and resins are close to the average value 6.227 × 10−4 cm2/s in the MD model. Self-healing is mainly based on the Van der Waals forces between non-bonded molecules. The aging of asphalt molecules reduces the diffusion rate of the asphalt model, and the SBS additive indirectly enhances the diffusion rate of asphalt.
Liang He; Guannan Li; Songtao Lv; Jie Gao; Karol J. Kowalski; Jan Valentin; Alessio Alexiadis. Self-healing behavior of asphalt system based on molecular dynamics simulation. Construction and Building Materials 2020, 254, 119225 .
AMA StyleLiang He, Guannan Li, Songtao Lv, Jie Gao, Karol J. Kowalski, Jan Valentin, Alessio Alexiadis. Self-healing behavior of asphalt system based on molecular dynamics simulation. Construction and Building Materials. 2020; 254 ():119225.
Chicago/Turabian StyleLiang He; Guannan Li; Songtao Lv; Jie Gao; Karol J. Kowalski; Jan Valentin; Alessio Alexiadis. 2020. "Self-healing behavior of asphalt system based on molecular dynamics simulation." Construction and Building Materials 254, no. : 119225.
To describe the interaction of fatigue-creep damage of an asphalt mixture under the action of semi-sine cyclic loading reasonably, a direct tension fatigue test was carried out under four different stress levels (0.5, 1, 1.5, and 2 MPa) based on the fact that semi-sine fatigue stress can be decomposed into creeping stress and simple fatigue stress. In addition, tension-compression fatigue and static creep tests were carried out under four stress levels: 0.25, 0.5, 0.75, 1 MPa. For each test, five parallel tests were carried out at the same stress level. The Chaboche fatigue damage model and Kachanov creep damage model were employed to evaluate the damage evolution of the mixture both in the fatigue and creep tests. According to the test results, the damage evolution trends were revealed under different test processes and stress levels, and the damage evolution models of three different test methods were obtained. Then, based on the principle of semi-sine fatigue stress decomposition, a fatigue-creep damage interaction model considering the interaction of fatigue and creep damage was established using normalized parameters (X = N/Nf = t/tR) as the intermediate variable. The results indicated that the damage of asphalt mixture under the action of the semi-sine cyclic load was not a simple linear accumulation of fatigue damage and creep damage, but an overall result of the interaction of fatigue damage, creep damage, and fatigue-creep damage. The fatigue-creep damage interaction model provided a good fit with the experimental data and showed a high degree of consistency with the classical damage model. The model could be used to describe the damage evolution trend of asphalt mixture under the action of semi-sine cycle load and the interaction effect of fatigue damage and creep damage.
Hongfu Liu; Xinyu Yang; Lijun Jiang; Songtao Lv; Tuo Huang; Yi Yang. Fatigue-creep damage interaction model of asphalt mixture under the semi-sine cycle loading. Construction and Building Materials 2020, 251, 119070 .
AMA StyleHongfu Liu, Xinyu Yang, Lijun Jiang, Songtao Lv, Tuo Huang, Yi Yang. Fatigue-creep damage interaction model of asphalt mixture under the semi-sine cycle loading. Construction and Building Materials. 2020; 251 ():119070.
Chicago/Turabian StyleHongfu Liu; Xinyu Yang; Lijun Jiang; Songtao Lv; Tuo Huang; Yi Yang. 2020. "Fatigue-creep damage interaction model of asphalt mixture under the semi-sine cycle loading." Construction and Building Materials 251, no. : 119070.
The objective of this paper is to propose a normalized characterization method based on the yield criterion to eliminate the impacts of different stress models on the fatigue behaviors characterization of cement-treated aggregates. Based on the theory of octahedral shear stress strength and yield surface mode, the yield surface of cement-treated aggregates was established with four-point bending, compression, and indirect tensile strength value under different loading rates. Then, the fatigue stress and corresponding ultimate strength could be characterized by the yield surface, uniformly and uniquely. In the yield surface space (I1, J2), the fatigue stress growth route from initial stress to ultimate strength was identified as fatigue stress path. Based on the fatigue stress path, the fatigue stress ratios related to loading rate and stress model were calculated. With these stress ratios, the conventional S-N fatigue equation was modified, on the basis of which a normalized characterization method of fatigue behavior was proposed to characterize the fatigue behavior of cement-treated aggregates. Compared with the traditional characterized method, the normalized characterization method has considered the influence of loading rate and stress model on strength and fatigue test results. The test results demonstrated that different strength and fatigue test results were obtained under distinct stress model and loading rates. All strength values have been expressed indiscriminately in the yield surface. With the normalized characterization method, a unique fatigue curve was gained for cement-treated aggregates under different loading rates and stress models. Therefore, findings of this work realized the normalization characterization of fatigue behavior of cement-treated aggregates.
Chaochao Liu; Songtao Lv; Xinghai Peng; Jianlong Zheng. Normalized characterization method for fatigue behavior of cement-treated aggregates based on the yield criterion. Construction and Building Materials 2019, 228, 117099 .
AMA StyleChaochao Liu, Songtao Lv, Xinghai Peng, Jianlong Zheng. Normalized characterization method for fatigue behavior of cement-treated aggregates based on the yield criterion. Construction and Building Materials. 2019; 228 ():117099.
Chicago/Turabian StyleChaochao Liu; Songtao Lv; Xinghai Peng; Jianlong Zheng. 2019. "Normalized characterization method for fatigue behavior of cement-treated aggregates based on the yield criterion." Construction and Building Materials 228, no. : 117099.
Songtao Lv; Chengdong Xia; Lingyun You; Xiaofeng Wang; Jianglong Li; Jianlong Zheng. Unified fatigue characteristics model for cement-stabilized macadam under various loading modes. Construction and Building Materials 2019, 223, 775 -783.
AMA StyleSongtao Lv, Chengdong Xia, Lingyun You, Xiaofeng Wang, Jianglong Li, Jianlong Zheng. Unified fatigue characteristics model for cement-stabilized macadam under various loading modes. Construction and Building Materials. 2019; 223 ():775-783.
Chicago/Turabian StyleSongtao Lv; Chengdong Xia; Lingyun You; Xiaofeng Wang; Jianglong Li; Jianlong Zheng. 2019. "Unified fatigue characteristics model for cement-stabilized macadam under various loading modes." Construction and Building Materials 223, no. : 775-783.
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.
Juan Xie; Yueming Yang; Songtao Lv; Yongning Zhang; Xuan Zhu; Cece Zheng. Investigation on Rheological Properties and Storage Stability of Modified Asphalt Based on the Grafting Activation of Crumb Rubber. Polymers 2019, 11, 1563 .
AMA StyleJuan Xie, Yueming Yang, Songtao Lv, Yongning Zhang, Xuan Zhu, Cece Zheng. Investigation on Rheological Properties and Storage Stability of Modified Asphalt Based on the Grafting Activation of Crumb Rubber. Polymers. 2019; 11 (10):1563.
Chicago/Turabian StyleJuan Xie; Yueming Yang; Songtao Lv; Yongning Zhang; Xuan Zhu; Cece Zheng. 2019. "Investigation on Rheological Properties and Storage Stability of Modified Asphalt Based on the Grafting Activation of Crumb Rubber." Polymers 11, no. 10: 1563.
The objective of this paper is to reveal the effects of aging on the fatigue performance of asphalt mixture based on variation patterns of fatigue parameters with aging degrees. Specimens with different aging degrees were prepared by modified SHRP’s Long-Term-Oven Aging (LTOA) test method, in which five different aging durations, included 0, 1, 3, 5, 7 days, were adopted to substitute the fixed 5 days. The fatigue parameters, including stiffness modulus, fatigue life, phase angle, Plateau Value (PV), and cumulative dissipation energy of specimens with different aging degrees under different stress ratios were obtained by the tensile fatigue test. The relationship of fatigue parameters with aging degrees and stress ratios were established. It could be observed from the results that the aging degree and stress ratio had dramatic influences on the fatigue performance of asphalt mixture. Sensitivity analysis showed that aging had the most significant effect on the initial stiffness modulus of asphalt mixture, and should be used as a control index in fatigue design. Statistical models of the relation between (PV) and fatigue life (Nf) established by the Rate of Dissipated Energy Change (RDEC) approach has an effective correlation. The Plateau Value model eliminated the effects of aging degrees and reflected the uniqueness of material parameters. Also, it could provide novel ideas for effective prediction of the fatigue life of asphalt mixtures with different aging degrees based on plateau value.
Songtao Lv; Xinghai Peng; Chaochao Liu; Dongdong Ge; Minmin Tang; Jianlong Zheng. Laboratory investigation of fatigue parameters characteristics of aging asphalt mixtures: A dissipated energy approach. Construction and Building Materials 2019, 230, 116972 .
AMA StyleSongtao Lv, Xinghai Peng, Chaochao Liu, Dongdong Ge, Minmin Tang, Jianlong Zheng. Laboratory investigation of fatigue parameters characteristics of aging asphalt mixtures: A dissipated energy approach. Construction and Building Materials. 2019; 230 ():116972.
Chicago/Turabian StyleSongtao Lv; Xinghai Peng; Chaochao Liu; Dongdong Ge; Minmin Tang; Jianlong Zheng. 2019. "Laboratory investigation of fatigue parameters characteristics of aging asphalt mixtures: A dissipated energy approach." Construction and Building Materials 230, no. : 116972.
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.
Xiyan Fan; Weiwei Lu; Songtao Lv; Fangwei He. Improvement of Low-Temperature Performance of Buton Rock Asphalt Composite Modified Asphalt by Adding Styrene-Butadiene Rubber. Materials 2019, 12, 2358 .
AMA StyleXiyan Fan, Weiwei Lu, Songtao Lv, Fangwei He. Improvement of Low-Temperature Performance of Buton Rock Asphalt Composite Modified Asphalt by Adding Styrene-Butadiene Rubber. Materials. 2019; 12 (15):2358.
Chicago/Turabian StyleXiyan Fan; Weiwei Lu; Songtao Lv; Fangwei He. 2019. "Improvement of Low-Temperature Performance of Buton Rock Asphalt Composite Modified Asphalt by Adding Styrene-Butadiene Rubber." Materials 12, no. 15: 2358.
In order to describe the fatigue damage state of asphalt mixture more reasonably, direct tensile tests of the fatigue and the residual strength under stress levels of 1.00 MPa, 0.50 MPa and 0.25 MPa with five parallel tests were carried out. The trabecular specimens of AC-13C asphalt mixture (25 cm × 5 cm × 5 cm) were manufactured with Styrene-Butadiene-Styrene (SBS) modified asphalt, aggregate basalt and limestone mineral filler. The optimum asphalt-aggregate ratio was 5.2%. The dynamic modulus decay and the residual strength decay were termed as the damage variables to evaluate the fatigue damage process of asphalt mixtures, respectively. Based on the test results, the decay patterns of the dynamic modulus and the residual strength during fatigue tests under different stress states were revealed, and the model and the parameters of fatigue damage according to the corresponding decay patterns were obtained. Then, based on the assumption that the residual strength and dynamic modulus depend on the same damage state, the relationship between the two damage definitions was given, and the residual strength-dynamic modulus coupled model was established. The results showed that the residual strength-dynamic modulus coupled model could better describe the fatigue damage evolution law of asphalt mixture, and the parameter of this coupled model could be obtained by less residual strength tests. A modified formula for calculating the damage variables associated with residual strength and dynamic modulus was proposed based on the relationship between two kinds of damage variables.
Hongfu Liu; Xinyu Yang; Chengdong Xia; Jianlong Zheng; Tuo Huang; Songtao Lv. Nonlinear Fatigue Damage Model of Asphalt Mixture Based on Dynamic Modulus and Residual Strength Decay. Materials 2019, 12, 2236 .
AMA StyleHongfu Liu, Xinyu Yang, Chengdong Xia, Jianlong Zheng, Tuo Huang, Songtao Lv. Nonlinear Fatigue Damage Model of Asphalt Mixture Based on Dynamic Modulus and Residual Strength Decay. Materials. 2019; 12 (14):2236.
Chicago/Turabian StyleHongfu Liu; Xinyu Yang; Chengdong Xia; Jianlong Zheng; Tuo Huang; Songtao Lv. 2019. "Nonlinear Fatigue Damage Model of Asphalt Mixture Based on Dynamic Modulus and Residual Strength Decay." Materials 12, no. 14: 2236.
The cement stabilized macadam base experiences tensile and compressive stresses simultaneously in the actual pavement structures, resulting in the influence of stress states on fatigue performance. In this paper, the fatigue performance of cement stabilized macadam was analyzed based on modulus decay considering the difference between compressive and tensile modulus. A synchronous measurement method of tensile and compressive modulus, which based on convention four-point bending test, was utilized to measure modulus of cement stabilized macadam during a fatigue test. The four-point bending fatigue test was conducted upon four different stress levels of 0.25 MPa, 0.5 MPa, 1.0 MPa, and 1.5 MPa. The average of 10 closest modulus values nearby the first 1% of fatigue life was adopted to determine the initial modulus. The last 5 cycles before the failure of the specimen in the fatigue test was determined as the critical modulus value. It was observed from the tests results that the critical value of compressive fatigue modulus was 8 times higher than that of tensile fatigue modulus. The initial and critical values of both tensile and compression decreased with the increase of stress levels. Under different stress levels, the modulus decay mode of tensile and compressive modulus was similar, but the decay rates of tensile modulus were higher than that of compressive modulus. Based on the modulus decay mode, the concept of critical failure point was put forward to characterize the fatigue behavior of cement stabilized macadam. During the fatigue process, both tensile and compressive modulus decay presented three stages, i.e. preliminary stage, stable stage, and rapid attenuation stage. The stable stage of tensile modulus was shorter than that of compressive modulus, which means that the primary fatigue damage occurred in the tensile zone.
Songtao Lv; Jiang Yuan; Chaochao Liu; Jiaqing Wang; Jianglong Li; Jianlong Zheng. Investigation of the fatigue modulus decay in cement stabilized base material by considering the difference between compressive and tensile modulus. Construction and Building Materials 2019, 223, 491 -502.
AMA StyleSongtao Lv, Jiang Yuan, Chaochao Liu, Jiaqing Wang, Jianglong Li, Jianlong Zheng. Investigation of the fatigue modulus decay in cement stabilized base material by considering the difference between compressive and tensile modulus. Construction and Building Materials. 2019; 223 ():491-502.
Chicago/Turabian StyleSongtao Lv; Jiang Yuan; Chaochao Liu; Jiaqing Wang; Jianglong Li; Jianlong Zheng. 2019. "Investigation of the fatigue modulus decay in cement stabilized base material by considering the difference between compressive and tensile modulus." Construction and Building Materials 223, no. : 491-502.
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.
Juan Xie; Yueming Yang; Songtao Lv; Xinghai Peng; Yongning Zhang. Investigation on Preparation Process and Storage Stability of Modified Asphalt Binder by Grafting Activated Crumb Rubber. Materials 2019, 12, 2014 .
AMA StyleJuan Xie, Yueming Yang, Songtao Lv, Xinghai Peng, Yongning Zhang. Investigation on Preparation Process and Storage Stability of Modified Asphalt Binder by Grafting Activated Crumb Rubber. Materials. 2019; 12 (12):2014.
Chicago/Turabian StyleJuan Xie; Yueming Yang; Songtao Lv; Xinghai Peng; Yongning Zhang. 2019. "Investigation on Preparation Process and Storage Stability of Modified Asphalt Binder by Grafting Activated Crumb Rubber." Materials 12, no. 12: 2014.
The objectives of this study are to explore the mechanism of the self-healing or flow of asphalt binder on the surface of the aggregates and evaluate the contact angle between the asphalt binder and aggregates. The mastic samples (small size) were prepared with asphalt binder and fine aggregates of a small size (below 0.3 mm). The microscale dynamic X-ray tomography was used to observe the flow of asphalt binder in the mastic sample at 353.15 K (80 °C) using the Advanced Photon Source (APS) beamline 2-BM at Argonne National Laboratory. The activation energy for flow of the asphalt binder and the contact angle between the asphalt binder and aggregates were analyzed to explain the self-healing characteristics of the asphalt binder materials. The Molecular Dynamics (MD) method was employed to simulate the flow process of the molecules of asphalt binder at different temperatures and mimic the contact angle difference between the asphalt binder and aggregate models. Simultaneously, in the laboratory, the contact angle goniometer was selected to measure the contact angle between the asphalt binder droplet and aggregates at different temperatures. The results of tests and MD simulations show that (1) asphalt binder diffused after heating from the X-ray images, and the stages and mechanism of the flow process of asphalt binder on aggregates were investigated; (2) low contact angle was observed in the interface model of asphalt binder and aggregates at high temperatures using the MD method. The wetting condition changed from partial non-wetting to wetting after heating in the interface model; (3) contact angle results between the asphalt binder and aggregates demonstrated flow steps of the asphalt binder material. The test data was also compared with the MD simulation results at different temperatures.
Hui Yao; Qingli Dai; Zhanping You; Jinxi Zhang; Songtao Lv; Xianghui Xiao. Evaluation of contact angle between asphalt binders and aggregates using Molecular Dynamics (MD) method. Construction and Building Materials 2019, 212, 727 -736.
AMA StyleHui Yao, Qingli Dai, Zhanping You, Jinxi Zhang, Songtao Lv, Xianghui Xiao. Evaluation of contact angle between asphalt binders and aggregates using Molecular Dynamics (MD) method. Construction and Building Materials. 2019; 212 ():727-736.
Chicago/Turabian StyleHui Yao; Qingli Dai; Zhanping You; Jinxi Zhang; Songtao Lv; Xianghui Xiao. 2019. "Evaluation of contact angle between asphalt binders and aggregates using Molecular Dynamics (MD) method." Construction and Building Materials 212, no. : 727-736.
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.
Songtao Lv; Chengdong Xia; Chaochao Liu; Jianlong Zheng; Fangchao Zhang. Fatigue equation for asphalt mixture under low temperature and low loading frequency conditions. Construction and Building Materials 2019, 211, 1085 -1093.
AMA StyleSongtao Lv, Chengdong Xia, Chaochao Liu, Jianlong Zheng, Fangchao Zhang. Fatigue equation for asphalt mixture under low temperature and low loading frequency conditions. Construction and Building Materials. 2019; 211 ():1085-1093.
Chicago/Turabian StyleSongtao Lv; Chengdong Xia; Chaochao Liu; Jianlong Zheng; Fangchao Zhang. 2019. "Fatigue equation for asphalt mixture under low temperature and low loading frequency conditions." Construction and Building Materials 211, no. : 1085-1093.
Although the rutting resistance, fatigue cracking, and the resistance to water and frost are important for the asphalt pavement, the strength of asphalt mixture is also an important factor for the asphalt mixture design. The strength of asphalt mixture is directly associated with the overall performance of asphalt mixture. As a top layer material of asphalt pavement, the strength of asphalt mixture plays an indispensable role in the top structural bearing layer. In the present design system, the strength of asphalt pavement is usually achieved via the laboratory tests. The stress states are usually different for the different laboratory approaches. Even at the same stress level, the laboratory strengths of asphalt mixture obtained are significantly different, which leads to misunderstanding of the asphalt mixtures used in asphalt pavement structure design. The arbitrariness of strength determinations affects the effectiveness of the asphalt pavement structure design in civil engineering. Therefore, in order to overcome the design deviation caused by the randomness of the laboratory strength of asphalt mixtures, in this study, the direct tension, indirect tension, and unconfined compression tests were implemented on the specimens under different loading rates. The strength model of asphalt mixture under different loading modes was established. The relationship between the strength ratio and loading rate of direct tension, indirect tension, and unconfined compression tests was adopted separately. Then, one unified strength model of asphalt mixture with different loading modes was established. The preliminary results show that the proposed unified strength model could be applied to improve the accurate degree of laboratory strength. The effectiveness of laboratory-based asphalt pavement structure design can therefore be promoted.
Chengdong Xia; Songtao Lv; Lingyun You; Dong Chen; Yipeng Li; Jianlong Zheng. Unified Strength Model of Asphalt Mixture under Various Loading Modes. Materials 2019, 12, 889 .
AMA StyleChengdong Xia, Songtao Lv, Lingyun You, Dong Chen, Yipeng Li, Jianlong Zheng. Unified Strength Model of Asphalt Mixture under Various Loading Modes. Materials. 2019; 12 (6):889.
Chicago/Turabian StyleChengdong Xia; Songtao Lv; Lingyun You; Dong Chen; Yipeng Li; Jianlong Zheng. 2019. "Unified Strength Model of Asphalt Mixture under Various Loading Modes." Materials 12, no. 6: 889.
Modulus testing methods under various test conditions have a large influence on modulus test results, which hinders the accurate evaluation of the stiffness of asphalt mixtures. In order to decrease the uncertainty in the stiffness characteristics of asphalt mixtures under various stress states, the traditional unconfined compression test, direct tensile test, and the synchronous test method, based on the indirect tension and four-point bending tests, were carried out for different loading frequencies. Results showed that modulus test results were highly sensitive to the shape, size, and stress state of the specimen. Additionally, existing modulus characteristics did not reduce these differences. There is a certain correlation between the elastic modulus ratio and the frequency ratio for asphalt under multiple stress states. The modulus, under multiple stress states, was processed using min–max normalization. Then, the standardization model for tensile and compressive characteristics of asphalt under diverse stress states was established based on the sample preparation, modulus ratio variations, and loading frequency ratio. A method for deriving other moduli from one modulus was realized. It is difficult to evaluate the stiffness performance in diverse stress states for asphalt by only using conventional compressive and tensile tests. However, taking into account the effects of stress states and loading frequencies, standardized models can be used to reduce or even eliminate these effects. The model realizes the unification of different modulus test results, and provides a theoretical, methodological, and technical basis for objectively evaluating moduli.
Xiyan Fan; Songtao Lv; Naitian Zhang; Chengdong Xia; Yipeng Li. Characterization of Asphalt Mixture Moduli under Different Stress States. Materials 2019, 12, 397 .
AMA StyleXiyan Fan, Songtao Lv, Naitian Zhang, Chengdong Xia, Yipeng Li. Characterization of Asphalt Mixture Moduli under Different Stress States. Materials. 2019; 12 (3):397.
Chicago/Turabian StyleXiyan Fan; Songtao Lv; Naitian Zhang; Chengdong Xia; Yipeng Li. 2019. "Characterization of Asphalt Mixture Moduli under Different Stress States." Materials 12, no. 3: 397.