作者： Lv, Songtao;Peng, Xinghai;Liu, Chaochao*;Qu, Fangting;Zhu, Xuan;...

期刊： Journal of Cleaner Production,2020年257:120589 ISSN：0959-6526

通讯作者： Liu, Chaochao

作者机构： [Zhu, Xuan; Tian, Weiwei; Peng, Xinghai; Qu, Fangting; Lv, Songtao; Zheng, Jianlong; Liu, Chaochao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Liu, Chaochao] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Hunan, Peoples R China.

关键词： Asphalt pavements;Binders;Deterioration;High temperature properties;Highway engineering;Rheology;Rheometers;Scanning electron microscopy;Temperature;Asphalt aging;Eco-friendly materials;High temperature performance;Low temperature performance;Microscopic characteristics;Multiple stress creep recoveries;Rock asphalts;Rolling thin-film oven tests;Asphalt

摘要： In order to improve the aging resistance of bio-asphalt, the Buton-rock asphalt (BRA) was selected to modify bio-asphalt. The rheological and Micro-property tests were performed on four types of BRA modified bio-asphalt under different aging degrees. The bio-asphalt with 5% contents of bio-oil was prepared as the base binder. The BRA contents for the four types of BRA modified bio-asphalt were 5%, 10%, 15%, and 20% by weight of the base binder. A series of rheological property tests were performed on BRA modified bio-asphalt with unaged or aged by rolling thin film oven test (RTFOT), or pressure aging vessel (PAV) test for 5 h, 15 h, or 20 h, respectively. The dynamic shear rheometer (DSR) was utilized to reveal the sensitivity of high-temperature properties to aging, including temperature sweep (TS) test at 60 °C and multiple stress creep recovery (MSCR) test at 58 °C. The deterioration of low-temperature performance was demonstrated by the bending beam rheometer (BBR). The effects of aging on the microstructures of the binders were investigated by scanning electron microscopy (SEM). The results show that the BRA improves the high-temperature performance of bio-asphalt, and the higher the content of BRA, the more remarkable the increase is. The BRA modified bio-asphalt is generally more sensitive to aging compared to neat asphalt. The high-temperature properties of BRA modified bio-asphalt with 20% BRA content is equivalent to neat asphalt. The bio-oil greatly improves the low-temperature rheological properties of BRA modified asphalt. The BRA improves the sensitivity of bio-asphalt to aging under low-temperature conditions. The suggested optimal content range of BRA is 15%–20%. The micro-surface of the BRA modified bio-asphalt is flat and has no void structure, crack-free and silver streaks appear after aging. The developed BRA modified bio-asphalt can meet the technical requirements of highway engineering and has outstanding aging resistance. The use of BRA and bio-oil can reduce the consumption of petroleum asphalt, dramatically reduce the cost of materials, and produce exceptional ecological benefits. © 2020 Elsevier Ltd

语种： 英文

作者： 郑健龙;吕松涛;刘超超

期刊： 科学通报,2020年65(30):3219-3227 ISSN：0023-074X

作者机构： 长沙理工大学交通运输工程学院,长沙410114;长沙理工大学公路养护技术国家工程实验室,长沙410114;[郑健龙; Lü S.; 刘超超] School of Traffic and Transportation Engineering, Changsha University of Science & Technology, Changsha, 410114, China<&wdkj&>National Engineering Laboratory of Highway Maintenance Technology, Changsha University of Science & Technology, Changsha, 410114, China

关键词： Asphalt pavements;Decision making;Decision theory;Design;Durability;Failure (mechanical);Ice problems;Maintenance;Mixtures;Motor transportation;Thermal fatigue;Traffic congestion;Intelligent decision making;Mechanical response characteristics;Method of mechanical analysis;Pavement maintenance management;Performance characteristics;Reclaimed asphalt pavements;Three dimensional stress state;Three-dimensional structure;Asphalt mixtures

摘要： <正>改革开放以来,我国公路交通事业取得了令人瞩目的巨大成就.截至2019年底,我国公路通车总里程为500多万千米,居世界第二位,高速公路总里程达14万多千米,居世界第一位,有力地支撑了中国的经济发展.但是,我国公路基础设施的人均占有量仅为美国的1/4左右,预计在2035年以前,我国还将新建普通公路1×106 km、高速公路5×104km以上.可见,我国高速公路建设任务依然繁重.

语种： 中文

作者： Pan, Q. X.*;Zheng, J. L.;Wen, P. H.*

期刊： Theoretical and Applied Fracture Mechanics,2020年105:102424 ISSN：0167-8442

通讯作者： Pan, Q. X.;Wen, P. H.

作者机构： [Pan, Q. X.; Zheng, J. L.] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Key Lab Rd Struct & Mat, Minist Transport Changsha, Changsha 410114, Hunan, Peoples R China.;[Wen, P. H.] Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

通讯机构： [Pan, Q. X.] C;[Wen, P. H.] Q;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Key Lab Rd Struct & Mat, Minist Transport Changsha, Changsha 410114, Hunan, Peoples R China.;Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

关键词： Bi-modular material;Fracture mechanics;General 3D shear modulus;3D complemented algorithm;Finite element method;Stress intensity factors

摘要： For rock-like and asphalt-mixture materials, the differences in Young's moduli and Poisson ratios are large under the tensile and compressive stress states. Therefore, for fracture mechanics, the stress and displacement fields near the crack tip described by William's series for classical elasticity (single-modulus of material) should be investigated. In this paper, a novel 2D/3D complemented algorithm is established by complementing the constitutive equations of shear modulus. The algorithm is implemented in ABAQUS with the subroutine UMAT and extended to bi-modular plate and cylindrical bar containing a central or edge cracks. It is proved that, for the mode I fracture, the solutions for the stress and displacement given by William's series are valid for bi-modular materials. In addition, the convergence of numerical algorithm is demonstrated with different element density in the first example.

语种： 英文

作者： Liang, Bo*;Shi, Kai;Niu, Yanfang;Liu, Zhengchun;Zheng, Jianlong

期刊： Construction and Building Materials,2020年234:117385 ISSN：0950-0618

通讯作者： Liang, Bo

作者机构： [Liu, Zhengchun; Liang, Bo; Shi, Kai; Niu, Yanfang; Zheng, Jianlong] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, State Engn Lab Highway Maintenance Technol, Changsha 410114, Peoples R China.;[Liu, Zhengchun; Niu, Yanfang] Cent South Univ, Sch Phys & Elect, Hunan Key Lab Super Microstruct & Ultrafast Proc, Changsha 410083, Peoples R China.

通讯机构： [Liang, Bo] C;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, State Engn Lab Highway Maintenance Technol, Changsha 410114, Peoples R China.

关键词： SBS-modified asphalt;Potentiometric titration;Modification mechanism;Quantitative design;Double bonds

摘要： Styrene-butadiene-styrene (SBS)-modified asphalt plays an integral role in asphalt pavements. To facilitate the understanding of the correlations between the physical and chemical properties of asphalt cement and SBS, a method for the direct quantitative determination of the SBS modification mechanism via potentiometric titration is proposed. This method will theoretically guide the processing design of SBS-modified asphalts. Potentiometric titration is applied to investigate the unsaturation of SBS-mixed, SBS-modified, and SBS/sulfur-modified asphalts with different SBS dosages ranging from 0% to 10%. The unsaturation of SBS-mixed asphalt exhibits a good linear increase with an increase in SBS dosage. A noticeable loss of SBS unsaturation occurs in SBS- and SBS/sulfur-modified asphalts after undergoing complete modification. In addition, unsaturation presents an evident inflection point at approximately 5 wt% SBS with an increase in SBS dosage. This finding indicates SBS changing from a dispersed phase to a continuous phase in the modified asphalts. Remarkably, the addition of sulfur can accelerate the emergence of an inflection point. Results corroborate that various types of virgin asphalt exhibit different inflection points. SBS/sulfur-modified asphalt demonstrates stronger chemical cross-linking than SBS-modified asphalt. These findings are further confirmed via fluorescence imaging, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. Potentiometric titration potentially provides a direct quantitative method for probing the modification mechanism of and designing customized processing for SBS-modified asphalts. © 2019 Elsevier Ltd

语种： 英文

作者： Pan, Qinxue*;Zheng, Jianlong;Wen, Pihua

期刊： 力学学报：英文版,2020年36(1):143-159 ISSN：0567-7718

通讯作者： Pan, Qinxue

作者机构： [Pan, Qinxue; Zheng, Jianlong] Changsha Univ Sci & Technol, Sch Traff,Key Lab Rd Struct,Mat Minist Transport, Transportat Engn, Changsha, Peoples R China.;[Wen, Pihua] Queen Mary Univ London, Sch Engn, Materials Sci, London, England.

通讯机构： [Pan, Qinxue] C;Changsha Univ Sci & Technol, Sch Traff,Key Lab Rd Struct,Mat Minist Transport, Transportat Engn, Changsha, Peoples R China.

关键词： Elastic theory;Bimodulus material;3D complemented algorithm;Finite element method;Generalized elastic law;General 3D shear modulus

摘要： The bimodulus material is a classical model to describe the elastic behavior of materials with tension–compression asymmetry. Due to the inherently nonlinear properties of bimodular materials, traditional iteration methods suffer from low convergence efficiency and poor adaptability for large-scale structures in engineering. In this paper, a novel 3D algorithm is established by complementing the three shear moduli of the constitutive equation in principal stress coordinates. In contrast to the existing 3D shear modulus constructed based on experience, in this paper the shear modulus is derived theoretically through a limit process. Then, a theoretically self-consistent complemented algorithm is established and implemented in ABAQUS via UMAT; its good stability and convergence efficiency are verified by using benchmark examples. Numerical analysis shows that the calculation error for bimodulus structures using the traditional linear elastic theory is large, which is not in line with reality. © 2019, The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature.

语种： 英文

作者： 吕松涛;刘超超;屈芳婷;郑健龙

期刊： 中国公路学报,2020年33(10):67-75 ISSN：1001-7372

通讯作者： Lyu, S.-T.

作者机构： 长沙理工大学交通运输工程学院,湖南长沙410114;[郑健龙; 屈芳婷; 刘超超; 吕松涛] 长沙理工大学

通讯机构： School of Traffic and Transport Engineering, Changsha University of Science and Technology, Changsha, China

关键词： 道路工程;沥青混合料;综述;疲劳性能表征;疲劳试验方法;疲劳方程

摘要： 针对沥青混合料疲劳耐久性设计参数的不确定性与不科学性问题,从疲劳试验方法及疲劳性能表征模型两方面对沥青混合料疲劳性能表征的发展现状、存在的问题进行了综述,并总结了其未来发展方向。沥青混合料疲劳性能主要通过室内外不同疲劳试验进行研究,不同试验方法所用沥青混合料试件的尺寸、形状,试件内部所处应力状态及试验条件皆各不相同,而沥青混合料是一种由沥青结合料与不同粒径矿料通过搅拌和碾压而成的多相、多组分、多尺度黏弹性混合料,其力学响应具有显著的时间、温度与应力状态相关性,不同试验方法所对应的加载速度、试验温度及应力状态存在较大的差异性,故其试验结果呈现出显著的不确定性,其疲劳性能表征模型参数也存在显著的差异性;此外,常用的室内材料疲劳试验方法大多为一维或二维应力状态下的疲劳试验,这与沥青路面结构实际服役过程中所处的三维应力状态不符;沥青混合料疲劳性能表征方程大多来源于一维应力状态下的疲劳试验结果,因此,用简单应力状态下的材料疲劳试验方法与性能表征模型难以客观表征三维应力状态下沥青路面结构的疲劳抗力,从而导致沥青路面疲劳耐久性设计存在较大的偏差。建议开发与沥青路面服役状态一致的三维应力状态下的疲劳试验方法,并建立三维应力状态下疲劳表征模型,以消除不同试验方法及试验条件对沥青混合料疲劳性能表征的影响,提高沥青混合料疲劳性能表征的有效性与完备性。

语种： 中文

作者： Liu, Chaochao;Lv, Songtao*;Peng, Xinghai;Zheng, Jianlong;Yu, Miao

期刊： Journal of Materials in Civil Engineering,2020年32(9) ISSN：0899-1561

通讯作者： Lv, Songtao

作者机构： [Peng, Xinghai; Lv, Songtao; Zheng, Jianlong; Liu, Chaochao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;[Yu, Miao] Chongqing Jiaotong Univ, Coll Civil Engn, Natl & Reg Engn Lab Transportat Construct Mat, 66 Xuefu Ave, Chongqing 400074, Peoples R China.

通讯机构： [Lv, Songtao] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.

关键词： Asphalt concrete;Binders;Concrete testing;Fatigue of materials;Fatigue testing;Stress analysis;Viscoelasticity;Different effects;Fatigue characteristics;Fatigue equations;Fatigue performance;Loading frequencies;Stress sensitivity;Theory of stress;Visco-elastic material;Concretes;aging;asphalt;concrete;fatigue;loading;pavement;stress

摘要： Asphaltic material is a kind of viscoelastic material, and its performance varies with test and materials conditions, such as stress states, temperatures, aging degree, gradations, and binders. The anti fatigue design of asphalt pavement has been stifled by these interferences. The objectives of this study are to reveal and compare the effects of loading frequency and aging degree on the fatigue performance of asphalt concretes. A series of tests for tensile fatigue on aged and unaged asphalt concretes were conducted at different loading frequencies. The theory of stress ratio considering different test conditions was proposed based on the conclusion that the stress ratio varies with stress loading rates. Then, the S-N fatigue equation was modified based on the theory. The fatigue test results were analyzed with the modified S-N fatigue equation to characterize the fatigue performance of asphalt concretes aged to different degrees under different loading frequencies. The different effects of these two factors on the fatigue characteristics of asphalt concretes were analyzed and compared. It could be found from the results that the influences of loading frequencies and aging degrees on fatigue characteristics of asphalt concrete were different. The fatigue test results of asphalt concrete under different loading frequencies could be characterized by one fatigue curve fitted by the modified S-N fatigue equation. It meant that the effects of loading frequency on fatigue were equivalent to the stress level. The fatigue test results of asphalt concrete with different aging degrees were fitted into different fatigue curves, respectively. The asphalt concretes aged 1 day had better fatigue life and more stable stress sensitivity than unaged asphalt concrete. When the aging degree was over 1 day, the fatigue performance deteriorated with the increase of aging degree. Moreover, it could be observed that the strength increased with the aging degrees when it was measured by the standard test loading rates. However, when the loading rates increased to a certain range, the contrary conclusion could be obtained because the viscoelasticity of asphalt concretes changed due to aging. © 2020 American Society of Civil Engineers.

语种： 英文

作者： 潘勤学;郑健龙

期刊： 土木工程学报,2020年53(1):110-117 ISSN：1000-131X

作者机构： 长沙理工大学道路结构与材料交通行业重点实验室(长沙),湖南长沙410114;长沙理工大学交通运输工程学院,湖南长沙410004;[郑健龙; 潘勤学] 长沙理工大学

关键词： 道路工程;路面力学计算方法;双模量理论;有限元方法;二次开发

摘要： 现行沥青路面设计理论为传统的线弹性理论,设计时采用抗压回弹模量作为材料刚度参数,并未充分考虑道路材料拉压模量具有显著差异的特点。为此,文章将双模量理论(即拉压模量不同弹性理论)引入到路面力学分析中,基于迭代思想建立考虑材料拉压模量不同的沥青路面结构数值计算方法,且利用ABAQUS二次开发平台UMAT编制计算子程序,对典型沥青路面结构进行力学分析。结果表明:路面关键点位的力学响应,基于双模量理论与传统线弹性理论的计算结果之间的偏差高达30%~ 50%,应引起高度重视;沥青路面表面存在着较大的拉应力和拉应变,应为沥青路面破坏源之一,建议将沥青面层的设计点位从层底移至路表轮隙区;应用双模量理论对路面结构进行力学分析可有效地解决道路材料弹性模量的不唯一性问题。

语种： 中文

作者： Pan, Q. X.;Zheng, J. L.;Li, Qianxi;Wen, P. H.*

期刊： European Journal of Mechanics A-Solids,2020年80:103904 ISSN：0997-7538

通讯作者： Wen, P. H.

作者机构： [Pan, Q. X.; Zheng, J. L.] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha, Peoples R China.;[Li, Qianxi] Hunan Inst Metrol & Test, Changsha 410014, Hunan, Peoples R China.;[Wen, P. H.] Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

通讯机构： [Wen, P. H.] Q;Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

关键词： Bimodular Young's modulus;Continuous modes of Young's modulus;Meshless finite block method;Nonlinear partial differential equation;Stress intensity factors

摘要： Due to the differences in Young's moduli under the tensile and compressive loadings for a rock-like and asphalt-mixture materials, the analysis becomes difficult as all coefficients in Hook's law are dependent on the stress state in the field. In this paper, the meshless method is formulated for the first time to evaluate a cracked structure made of bimodular materials. In general, there are four stress zones in the field determined by the principal stresses. It is known that for classical elasticity (single modulus material), the stresses are singular at the crack tip described by William's series. For the pure mode I fracture, it is proved that the solutions for the stress and displacement by William's series are still valid for bimodular materials as there is only first kind zone in the vicinity of the crack tip. With the utilization of the Lagrange series, the meshless Finite Block Method (FBM) is demonstrated to deal with cracked structures with bimodular materials. The numerical solutions of the partial differential equations with variable coefficients are solved in a strong form by using the iterative technique. Numerical examples are demonstrated to verify the degree of accuracy and convergence with Finite Element Method (FEM) with very fine mesh. © 2019 Elsevier Masson SAS

语种： 英文

作者： Lv, Songtao;Xia, Chengdong*;Yang, Qing;Guo, Shuaicheng;You, Lingyun;...

期刊： Journal of Cleaner Production,2020年264:121745 ISSN：0959-6526

通讯作者： Xia, Chengdong

作者机构： [Guo, Yanpeng; Xia, Chengdong; Lv, Songtao; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Peoples R China.;[Yang, Qing] Xiangtan Univ, Sch Publ Adm, Xiangtan 411105, Peoples R China.;[Guo, Shuaicheng] Hunan Univ, Key Lab Green & Adv Civil Engn Mat & Applicat Tec, Changsha 410082, Peoples R China.;[You, Lingyun] Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

通讯机构： [Xia, Chengdong] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410114, Peoples R China.

关键词： Chemical modification;Compliance control;Creep;Creep resistance;Fourier transform infrared spectroscopy;Shells (structures);Stiffness;Thermodynamic stability;Dynamic shear modulus;Dynamic shear rheometer;Engineering applications;Environmental issues;Fourier transform infra red (FTIR) spectroscopy;High temperature stability;Modified asphalt binders;Multiple stress creep recoveries;Asphalt

摘要： 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 Jnr 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. © 2020 Elsevier Ltd

语种： 英文

作者： Jian-long Zheng;Zhanping You;Xueyan Liu

期刊： Applied Sciences-Basel,2020年10(21):7720 ISSN：2076-3417

通讯作者： You, Z.

作者机构： [Zheng J.-L.] School of Traffic and Transportation Engineering, Changsha University of Science and Technology (CSUST), Changsha, 410004, China;[You Z.] Department of Civil and Environmental Engineering, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, United States;[Liu X.] Pavement Engineering Section, Department of Engineering Structures, Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, 2628CN, Netherlands

通讯机构： [You, Z.] D;Department of Civil and Environmental Engineering, 1400 Townsend Drive, United States

关键词： Asphalt pavements;Durable road;Functional pavement;Green road;Intelligent road;Pavement materials;Safety pavement

摘要： In order to further promote the development of functional pavement technology, a Special Issue of “Achievements and Prospects of Functional Pavement” has been proposed by a group of guest editors. To reach this objective, articles included in this Special Issue are related to different aspects of functional pavement, including green roads to decrease carbon emission, noise, and pollution, safety pavement to increase skid resistance by water drainage and snow removal, intelligent roads for monitoring, power generation, temperature control and management, and durable roads to increase service life with new theory, new design methods, and prediction models, as highlighted in this editorial. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

语种： 英文

作者： Lv, Songtao;Peng, Xinghai;Liu, Chaochao*;Ge, Dongdong;Tang, Minmin;...

期刊： Construction and Building Materials,2020年230:116972 ISSN：0950-0618

通讯作者： Liu, Chaochao

作者机构： [Zheng, Jianiong; Peng, Xinghai; Lv, Songtao; Tang, Minmin; Liu, Chaochao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;[Ge, Dongdong; Liu, Chaochao] Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

通讯机构： [Liu, Chaochao] C;[Liu, Chaochao] M;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

关键词： Fatigue performance;Aging degree;Stiffness modulus;Plateau value (PV);Cumulative dissipation energy;Rate of dissipated energy change (RDEC)

摘要： 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 (N-f) 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. (C) 2019 Elsevier Ltd. All rights reserved.

语种： 英文

作者： Li, Jue;Zhang, Junhui*;Qian, Guoping;Zheng, Jianlong;Zhang, Yuqing

期刊： Journal of Materials in Civil Engineering,2019年31(3) ISSN：0899-1561

通讯作者： Zhang, Junhui

作者机构： [Zhang, Junhui; Qian, Guoping; Li, Jue; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410205, Hunan, Peoples R China.;[Zhang, Yuqing] Aston Univ, Sch Engn & Appl Sci, Aston Inst Mat Res, Birmingham B4 7ET, W Midlands, England.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410205, Hunan, Peoples R China.

关键词： Aggregates;Aspect ratio;Compression testing;Finite difference method;Geometry;Mechanical variables measurement;Mixtures;Parameterization;Probability distributions;Space-based radar;Vector spaces;Virtual reality;3-D numerical modeling;Correlation coefficient;Geometric characteristics;Irregular aggregates;Parameterized;Three dimensional simulations;Threedimensional (3-d);Uni-axial compression tests;Asphalt mixtures;aggregate;asphalt;computer simulation;discrete element method;numerical model;parameterization;size distribution;three-dimensional modeling

摘要： Aggregate occupies at least three-quarters of the volume of asphalt mixture and can significantly affect the performance of pavement. The geometrical morphology influences the slippage and interlock among aggregates for resisting and distributing applied loads. In recent years, the discrete-element method (DEM) has been employed for simulation of asphalt mixture structure. This paper introduces an approach for simulation of aggregate and asphalt mixtures using parameterized shape and size gradation. Both the plane geometry factor (PGF) and the section aspect ratio (SAR) were employed to describe the three-dimensional (3D) geometric characteristics of aggregates. A numerical technique of aggregate models was implemented with probabilistic parameters depending on statistical results of PGFs and SARs. The 3D numerical model of asphalt mixtures was assembled with three different components, and was validated by uniaxial compression tests via comparison with the laboratory result. It was found that the PGF and SAR are appropriate to describe the three-dimensional features of aggregate shapes, because a simplified space object can be described by a two-dimensional (2D) graphical projection and a vector scalar corresponding to the space vector. Probability distribution curves of PGFs and SARs between coarse aggregates were in concordance with the Gauss-type function, because their correlation coefficients were all greater than 95%. It was verified that the developed clumping algorithm of aggregates was reasonable in terms of the shape and size gradation. Based on the parallel-bond model and Burger's model, the results of virtual tests were in good agreement with those of laboratory uniaxial tests. The angularity (PGF) of aggregates has a beneficial effect on the strength and stability of asphalt mixtures, whereas the flat-elongated feature (SAR) has a negative effect on the strength and stability of asphalt mixtures. © 2019 American Society of Civil Engineers.

语种： 英文

作者： Liu, Hongfu*;Yang, Xinyu;Xia, Chengdong;Zheng, Jianlong;Huang, Tuo;...

期刊： Materials,2019年12(14):2236 ISSN：1996-1944

通讯作者： Liu, Hongfu

作者机构： [Liu, Hongfu] Changsha Univ Sci & Technol, Key Lab Rd Struct & Mat, Minist Transport Changsha, Changsha 410114, Hunan, Peoples R China.;[Huang, Tuo; Xia, Chengdong; Liu, Hongfu; Yang, Xinyu; Lv, Songtao; Zheng, Jianlong] Changsha Univ Sci & Technol, Coll Traff & Transportat Engn, Changsha 410114, Hunan, Peoples R China.

通讯机构： [Liu, Hongfu] C;Changsha Univ Sci & Technol, Key Lab Rd Struct & Mat, Minist Transport Changsha, Changsha 410114, Hunan, Peoples R China.;Changsha Univ Sci & Technol, Coll Traff & Transportat Engn, Changsha 410114, Hunan, Peoples R China.

关键词： Aggregates;Decay (organic);Fatigue damage;Fatigue testing;Lime;Mixtures;Styrene;Tensile testing;Damage evolution;Dynamic moduli;Fatigue damage models;Fatigue damage process;Nonlinear fatigue damages;Residual strength;Residual strength tests;Styrene butadiene styrene modified asphalt;Asphalt mixtures

摘要： 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. © 2019 by the authors.

语种： 英文

作者： Zhang, Junhui*;Peng, Junhui;Zheng, Jianlong;Dai, Liangliang;Yao, Yongsheng

期刊： International Journal of Geomechanics,2019年19(7):04019068 ISSN：1532-3641

通讯作者： Zhang, Junhui

作者机构： [Peng, Junhui; Yao, Yongsheng; Zhang, Junhui; Zheng, Jianlong] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Sci & Technol Innovat Platform, Changsha 410114, Hunan, Peoples R China.;[Dai, Liangliang] PE Jiaxing Highway Adm, Hangzhou 314000, Zhejiang, Peoples R China.

通讯机构： [Zhang, Junhui] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Sci & Technol Innovat Platform, Changsha 410114, Hunan, Peoples R China.

关键词： Embankments;Forecasting;Moisture determination;Shear flow;Shear stress;Soil moisture;Water content;Coefficient of determination;Compacted cohesive soils;Equilibrium moisture contents;Matric suctions;Optimum moisture content;Prediction model;Resilient modulus;The soil-water characteristic curves (SWCC);Soil testing;cohesive soil;elastic modulus;embankment;moisture content;numerical model;prediction;stress analysis;suction;triaxial test;China

摘要： The resilient modulus has been used to characterize the stress-strain nonlinear behavior of subgrade soils and is the primary property needed for pavement design and analysis. The degrees of stress and moisture content have a significant impact on the resilient modulus of compacted cohesive soils. Due to the hot, humid climate in South China, the moisture content in embankments will increase gradually from the optimum moisture content (OMC) - the design water content for embankments - to the equilibrium moisture content, which relates to soil properties and the surrounding climate. In this process, the resilient modulus of embankments will obviously decrease. In order to predict the resilient modulus of typical compacted cohesive soils in South China, repeated triaxial tests were carried out in this study. The soil matric suction was measured by the pressure plate test and the soil-water characteristic curve (SWCC) was described using the Van Genuchten model with a relatively high coefficient of determination. Then, the effect of the moisture content, degree of compaction, and stress state including the deviator stress, confining pressure, and octahedral shear stress to the resilient modulus were analyzed. In addition, a logarithmic function was utilized to build the relationship between the matric suction and resilient modulus. Subsequently, a new resilient modulus estimation model of compacted soils in South China, which took the bulk stress, octahedral shear, and matric suction as the model variables, was developed and verified using the data of different cohesive soils from different studies. The results show that the new model matches their data well, and the coefficients of determination are high, which indicates that this new model is reasonable and widely applicable. Finally, the correlations between the physical parameters of soil samples, such as the liquid limit, dry density, the maximum dry density, plasticity index, percentage passing through a 0.075-mm sieve, and the regression coefficients of the new model, were established. The resilient modulus can be predicted much more easily with these physical parameters of compacted cohesive soils rather than conducting triaxial tests. © 2019 American Society of Civil Engineers.

语种： 英文

作者： Lv, Songtao;Yuan, Jiang;Liu, Chaochao*;Wang, Jiaqing;Li, Jianglong;...

期刊： Construction and Building Materials,2019年223:491-502 ISSN：0950-0618

通讯作者： Liu, Chaochao

作者机构： [Li, Jianglong; Lv, Songtao; Yuan, Jiang; Zheng, Jianlong; Liu, Chaochao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;[Wang, Jiaqing; Liu, Chaochao] Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

通讯机构： [Liu, Chaochao] C;[Liu, Chaochao] M;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.;Michigan Technol Univ, Dept Civil & Environm Engn, 1400 Townsend Dr, Houghton, MI 49931 USA.

关键词： Cement stabilized macadam;Fatigue damage;Modulus decay;Tensile modulus;Compressive modulus

摘要： 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. © 2019 Elsevier Ltd

语种： 英文

作者： Liu, Chaochao;Lv, Songtao*;Peng, Xinghai;Zheng, Jianlong

期刊： Construction and Building Materials,2019年228:117099 ISSN：0950-0618

通讯作者： Lv, Songtao

作者机构： [Peng, Xinghai; Lv, Songtao; Zheng, Jianlong; Liu, Chaochao] Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.

通讯机构： [Lv, Songtao] C;Changsha Univ Sci & Technol, Natl Engn Lab Highway Maintenance Technol, Changsha 410004, Hunan, Peoples R China.

关键词： Cement-treated aggregate;Fatigue behavior;Normalized characterization;Yield criterion

摘要： 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. © 2019 Elsevier Ltd

语种： 英文

作者： Jin, Jiao*;Chen, Bozhen;Liu, Lang;Liu, Ruohua*;Qian, Guoping*;...

期刊： Materials,2019年12(12):ARTN 1910 ISSN：1996-1944

通讯作者： Jin, Jiao;Qian, Guoping;Liu, Ruohua

作者机构： [Jin, Jiao; Qian, Guoping; Wei, Hui; Liu, Lang; Zheng, Jianlong; Chen, Bozhen] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Hunan, Peoples R China.;[Liu, Ruohua] Cent S Univ, Sch Minerals Proc & Bioengn, Changsha 410083, Hunan, Peoples R China.

通讯机构： [Jin, J; Qian, GP; Liu, Ruohua] C;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha 410114, Hunan, Peoples R China.;Cent S Univ, Sch Minerals Proc & Bioengn, Changsha 410083, Hunan, Peoples R China.

关键词： Automobiles;Bituminous materials;Clay minerals;Degradation;Fiber optic sensors;Light absorption;Metal ions;Metals;Photocatalytic activity;Red Shift;Sol-gel process;Sol-gels;Titanium dioxide;Automobile exhaust;Bitumen;High temperature performance;Optical absorption edge;Photo catalytic degradation;Photo-catalytic;Photocatalytic performance;Pillared montmorillonite;Copper compounds

摘要： TiO2 pillared montmorillonite (T/M) modifiers have been studied to alleviate the aging of asphalt pavement and degrade automobile exhaust, but the photocatalytic activity of ordinary TiO2 is not good enough. In this study, in order to improve the photocatalytic performance of T/M, different metal (Ce, Cu, Fe) doped modifiers were prepared based on T/M. Metal doped TiO2 pillared montmorillonite was prepared by the sol-gel method. The modifier was characterized by X-ray diffraction (XRD) and an Ultraviolet visible (UV-Vis) spectrophotometer. The results show that TiO2 with different metal ions successfully entered into the layer of organic montmorillonite (OMMT) to form a pillared structure. Compared with the undoped TiO2 pillared montmorillonite (T/M), the optical absorption edge of the metal doped TiO2 pillared montmorillonite has an obvious red shift. In addition, the influences of the different content of modifiers on the properties of the original bitumen and catalytic capacities for automobile exhaust were also investigated. The results show that Ce doped TiO2 (Ce-T/M) pillared montmorillonite has the best improvement in high temperature performance and ultraviolet (UV) resistance of bitumen. In the experiment of automobile exhaust degradation, the degradation law of NO and HC showed Cu-T/M > Ce-T/M > Fe-T/M > T/M. These three kinds of metal ions can effectively improve the photocatalytic degradation efficiency of T/M.

语种： 英文

作者： Yang, Liu*;Zheng, Jianlong;Cheng, Yang;Ran, Bin

期刊： Physica A-Statistical Mechanics and its Applications,2019年535:122277 ISSN：0378-4371

通讯作者： Yang, Liu

作者机构： [Yang, Liu; Zheng, Jianlong] Changsha Univ Sci & Technol, Minist Educ, Key Lab Highway Engn, Changsha 410114, Hunan, Peoples R China.;[Ran, Bin; Yang, Liu; Cheng, Yang] Univ Wisconsin, Dept Civil & Environm Engn, Madison, WI 53706 USA.

通讯机构： [Yang, Liu] C;[Yang, Liu] U;Changsha Univ Sci & Technol, Minist Educ, Key Lab Highway Engn, Changsha 410114, Hunan, Peoples R China.;Univ Wisconsin, Dept Civil & Environm Engn, Madison, WI 53706 USA.

关键词： Freeway;Uphill;Climbing lane;Heterogeneous traffic flow;Cellular automata;Lane-changing model

摘要： Traffic congestions frequently occur on uphill segments of four-lane freeways in China, which have become typical bottlenecks. Therefore, this paper focuses on the analysis, modeling, and simulation of heterogeneous traffic flow on uphill, in order to understand and eliminate such bottlenecks. The traffic characteristics were obtained from the realistic data, and a cellular automata model for longitudinal driving and lane changing was proposed and validated. The longitudinal driving rules were established based on the Nagel–Scheckenberg model. Lane changing was classified into active, inactive, and mandatory types which were used to clearly describe asymmetric lane-changing rules on two-lane segments and uphill with a climbing lane. The expressions of lane-changing motivation and safety were established. The measured results show that cars and 6-axle articulated trucks are the main types, and the speed difference between them is large. For normal slopes with a high truck ratio, even the total traffic is light, cars are unable to run freely. The simulated results prove that the realistic lane changing is asymmetric. The effects of uphill and climbing lanes on traffic flow are related to density. Setting up a climbing lane can alleviate or eliminate the uphill bottleneck effect. A critical density for distinguishing free flow from non-free flow does not exist on two-lane segments but exists on the uphill with a climbing lane. Vehicle segregation is significant under asymmetric lane-changing rules. The segregation degree is related to the traffic flow state. © 2019 Elsevier B.V.

语种： 英文

作者： Jin, J.;Huang, T.*;Zheng, J. L.;Wen, P. H.*

期刊： Engineering Analysis with Boundary Elements,2019年99:122-130 ISSN：0955-7997

通讯作者： Huang, T.;Wen, P. H.

作者机构： [Huang, T.; Zheng, J. L.; Jin, J.] Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha, Hunan, Peoples R China.;[Wen, P. H.] Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

通讯机构： [Huang, T.] C;[Wen, P. H.] Q;Changsha Univ Sci & Technol, Sch Traff & Transportat Engn, Changsha, Hunan, Peoples R China.;Queen Mary Univ London, Sch Engn & Mat Sci, London E1 4NS, England.

关键词： Multi-dimensional partial differential equations;Semi-analytical solution;Finite difference method;Laplace transform;Dynamics;Functionally graded materials

摘要： Based on the Lagrange series interpolation, the semi-analytical and direct integration method (DIM) for solving the multi-dimensional partial differential equations are presented in this paper. A multidimensional problem can be simplified to a set of the ordinary differential equation by the mapping technique and Lagrange series interpolation (dimension reduction). The semi-analytical and numerical solutions by DIM are derived for the partial differential equation with variable coefficients. Comparisons with analytical solutions are performed in order to demonstrate the accuracy and efficiency of the proposed method.

语种： 英文