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As an environmentally friendly alternative for the production of high-performance modified asphalt by chemical reactions, a liquid-state polyurethane-precursor-based reactive modifier (PRM) was developed and employed in the asphalt modification. In contrast to the traditional solid bitumen modifier, for example, rubber and thermoplastic elastomers, the PRM as a liquid modifier has more significant advantages in reducing energy consumption and improving asphalt performance, which has attracted widespread attention. However, the aging resistance and its mechanism are not clear. In view of this, the aging performance of two PRM-modified bitumen (PRM-70 and PRM-90), under the short-term thermo-oxidative aging, long-term thermo-oxidative aging, and ultraviolet (UV) aging conditions, was investigated through chemical and mechanical methods. The results show that the PRM-90 is more susceptible to the thermos-oxidative aging and UV aging. The use of low-penetration-grade bitumen and ensuring an adequate reaction are beneficial to enhance the aging resistance of PRM-modified bitumen. The impact of aging on high-temperature performance of PRM-modified bitumen is great, followed by the low-temperature performance and the anti-fatigue performance. The mechanic-relevant rheological aging index (RAI) and fracture energy index (FEI) are recommended to evaluate aging properties for PRM-modified bitumen. This study not only provides support for further research on the relationship between the aging properties and mechanical performance of PRM-modified bitumen, but also provides a reference for conducting mechanism analysis.
Liang Zhang; Pengfei Li; Guanfeng Hu; Sufeng Zhang; Bin Hong; HaoPeng Wang; Dawei Wang; Markus Oeser. Study on the Aging Resistance of Polyurethane Precursor Modified Bitumen and its Mechanism. Sustainability 2021, 13, 9520 .
AMA StyleLiang Zhang, Pengfei Li, Guanfeng Hu, Sufeng Zhang, Bin Hong, HaoPeng Wang, Dawei Wang, Markus Oeser. Study on the Aging Resistance of Polyurethane Precursor Modified Bitumen and its Mechanism. Sustainability. 2021; 13 (17):9520.
Chicago/Turabian StyleLiang Zhang; Pengfei Li; Guanfeng Hu; Sufeng Zhang; Bin Hong; HaoPeng Wang; Dawei Wang; Markus Oeser. 2021. "Study on the Aging Resistance of Polyurethane Precursor Modified Bitumen and its Mechanism." Sustainability 13, no. 17: 9520.
The homogeneity of asphalt mixtures blended with reclaimed asphalt pavement (RAP) is affected by many factors. Due to the complicated compositions of recycled asphalt mixtures, the inhomogeneity issue might cause insufficient mechanical properties of asphalt mixtures, even though a design method was appropriately adopted. Therefore, it is of great significance to study the influence of mixing conditions on the homogeneity of asphalt mixtures blended with RAP materials. This study focused on the macro-scale homogeneity of produced asphalt mixtures. Specifically, asphalt mixtures incorporated with 40% RAP content were produced in a laboratory using different mixing times and mixing temperatures. A multi-direction indirect tensile stiffness modulus (ITSM) test was proposed to quantify the homogeneity of produced samples. In addition, the digital image processing (DIP) method was used to identify the distribution of aggregates and RAP binder. The results indicated that the influence of mixing time on the macro-homogeneity of asphalt mixtures indicated that a longer mixing time was favorable for the material dispersion. The influence of mixing temperature mainly rested on two perspectives. One was that the temperature variation induced the change of binder viscosity. The other was that the temperature influences the diffusion process between RAP binder and new bitumen, which further affected the mechanical performance of produced asphalt mixtures.
Quan Liu; Markus Oeser. The Influence of Mixing Conditions on the Macro-Scale Homogeneity of Asphalt Mixtures Blended with Reclaimed Asphalt Pavement (RAP). Materials 2021, 14, 4137 .
AMA StyleQuan Liu, Markus Oeser. The Influence of Mixing Conditions on the Macro-Scale Homogeneity of Asphalt Mixtures Blended with Reclaimed Asphalt Pavement (RAP). Materials. 2021; 14 (15):4137.
Chicago/Turabian StyleQuan Liu; Markus Oeser. 2021. "The Influence of Mixing Conditions on the Macro-Scale Homogeneity of Asphalt Mixtures Blended with Reclaimed Asphalt Pavement (RAP)." Materials 14, no. 15: 4137.
For road construction, the morphological characteristics of coarse aggregates such as angularity and sphericity have a considerable influence on asphalt pavement performance. In traditional aggregate simulation processes, images of real coarse grains are captured, and their parameters are extracted manually for reproducing them in a numerical simulation such as Discrete Element Modeling (DEM). Generative Adversarial Networks can generate aggregate images, which can be stored in the Aggregate DEM Database directly. In this paper, it has been demonstrated that applying Auxiliary Classifier Wasserstein GANs with gradient penalty (ACWGAN-gp) is reliable and efficient for the establishment of an aggregate image database. In addition, the distribution of original images was compared with that of images generated based on ACGAN and ACWGAN-gp models. Generated images were validated through obtaining identifiable edge coordinates and represented as DEM input in the simulation process. The results prove that the ACWGAN-gp approach can be used for generating aggregate images for the DEM database. It successfully generates high-quality images of aggregates with a representative distribution of morphologies used for DEM simulation. This work shows convenience and efficiency for machine learning applications in the road construction field.
Chonghui Wang; Feifei Li; Quan Liu; Hainian Wang; Pia Benmoussa; Sabina Jeschke; Markus Oeser. Establishment and extension of digital aggregate database using auxiliary classifier Wasserstein GAN with gradient penalty. Construction and Building Materials 2021, 300, 124217 .
AMA StyleChonghui Wang, Feifei Li, Quan Liu, Hainian Wang, Pia Benmoussa, Sabina Jeschke, Markus Oeser. Establishment and extension of digital aggregate database using auxiliary classifier Wasserstein GAN with gradient penalty. Construction and Building Materials. 2021; 300 ():124217.
Chicago/Turabian StyleChonghui Wang; Feifei Li; Quan Liu; Hainian Wang; Pia Benmoussa; Sabina Jeschke; Markus Oeser. 2021. "Establishment and extension of digital aggregate database using auxiliary classifier Wasserstein GAN with gradient penalty." Construction and Building Materials 300, no. : 124217.
Tire—pavement interaction behaviours result in large amounts of wearing waste matter, which attaches to the surface of the pavement and is directly exposed to the surrounding environment. This kind of matter imposes a great challenge to the environment of the road area. The current study is devoted to carrying out a comprehensive investigation of the formation mechanism of tire—pavement wearing waste (TPWW), as well as the resulting environmental risks. A self-developed piece of accelerated polishing equipment, the Harbin advanced polishing machine (HAPM), was employed to simulate the wearing process between vehicle tires and pavement surfaces, and the TPWW was collected to conduct morphological, physical, and chemical characterisations. The results from this study show that the production rate of TPWW decreases with the increase in polishing duration, and the coarse particles (diameters greater than 0.425 mm) account for most of the TPWW obtained. The fine fraction (diameter smaller than 0.425 mm) of the TPWW comprises variously sized and irregularly shaped rubber particles from the tire, as well as uniformly sized and angular fine aggregates. The environmental analysis results show that volatile alkanes (C9–C16) are the major organic contaminants in TPWW. The Open-Graded Friction Course (OGFC) asphalt mixture containing crumb rubber as a modifier showed the highest risk of heavy metal pollution, and special concern must be given to tire materials for the purpose of improving the environmental conditions of road areas. The use of polyurethane as a binder material in the production of pavement mixtures has an environmental benefit in terms of pollution from both organic contaminants and heavy metals.
Kechen Wang; Xiangyu Chu; Jiao Lin; Qilin Yang; Zepeng Fan; Dawei Wang; Markus Oeser. Investigation of the Formation Mechanism and Environmental Risk of Tire—Pavement Wearing Waste (TPWW). Sustainability 2021, 13, 8172 .
AMA StyleKechen Wang, Xiangyu Chu, Jiao Lin, Qilin Yang, Zepeng Fan, Dawei Wang, Markus Oeser. Investigation of the Formation Mechanism and Environmental Risk of Tire—Pavement Wearing Waste (TPWW). Sustainability. 2021; 13 (15):8172.
Chicago/Turabian StyleKechen Wang; Xiangyu Chu; Jiao Lin; Qilin Yang; Zepeng Fan; Dawei Wang; Markus Oeser. 2021. "Investigation of the Formation Mechanism and Environmental Risk of Tire—Pavement Wearing Waste (TPWW)." Sustainability 13, no. 15: 8172.
Increasing traffic loads, as well as changing climatic conditions generate the need for high performing flexible pavements, able to endure these new conditions. In recent years, many additives have been developed to make asphalt pavements last longer, preventing the typical asphalt distresses such as rutting, thermal cracking and fatigue cracking. In this investigation, a novel liquid, low-viscous chemical additive (B2Last®) is presented for its use in asphalt binders. Special emphasis was set on the modification procedure, where two different methods were studied: a batch modification and an in-line modification, both on a laboratory level. The isocyanate-based additive modification could be successfully followed with the help of attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) measurements. This technique allowed to identify specific functionalities and to follow the curing of the asphalt binder with the isocyanate-based additive until the completion of the reaction. Additionally, a comprehensive analysis, including conventional and rheological asphalt binder tests, was performed on different asphalt binder samples with 2,0% by wt. of additive. The results obtained from the mechanical properties show a clear increase in the stability against rutting, without affecting the low temperature behaviour. Moreover, the latter was supported with the analysis on the parameters of the 2S2P1D model. The isocyanate-based additive proved to enhance the asphalt performance.
Nicolás Héctor Carreño Gómez; Markus Oeser; Olivier Fleischel. Chemical modification of bitumen with novel isocyanate-based additive to enhance asphalt performance. Construction and Building Materials 2021, 301, 124128 .
AMA StyleNicolás Héctor Carreño Gómez, Markus Oeser, Olivier Fleischel. Chemical modification of bitumen with novel isocyanate-based additive to enhance asphalt performance. Construction and Building Materials. 2021; 301 ():124128.
Chicago/Turabian StyleNicolás Héctor Carreño Gómez; Markus Oeser; Olivier Fleischel. 2021. "Chemical modification of bitumen with novel isocyanate-based additive to enhance asphalt performance." Construction and Building Materials 301, no. : 124128.
The microstructure variation plays an essential role in the micro-mechanical performance of the bitumen and the macro-mechanical behavior of asphalt mixtures. This research aims to reveal the influence of the microstructure changes of bitumen on its micromechanical responses. Based on atomic force microscopy (AFM) technology, the microstructure (bee structure: bee, peri, and interstitial phases) of the bitumen was detected. With the self-developed microstructural finite element (FE) models, the micromechanical responses of bitumen with different bee structures were comprehensively simulated. The results show that the computational load-bearing capacity of the bitumen increases with an increase of the peri phase content, but the difference is not significant. The development of high stresses within the bee phase is mainly due to the inhomogeneity of the material. Additionally, the distribution of the tensile strain becomes more homogeneous with the increase of the peri phase content. This research contributes to establishing a better understanding of the relationship between the microstructure of the bitumen and its micromechanical properties.
Cong Du; Pengfei Liu; Kaloyan Ganchev; Guoyang Lu; Markus Oeser. Influence of microstructure evolution of bitumen on its micromechanical property by finite element simulation. Construction and Building Materials 2021, 293, 123522 .
AMA StyleCong Du, Pengfei Liu, Kaloyan Ganchev, Guoyang Lu, Markus Oeser. Influence of microstructure evolution of bitumen on its micromechanical property by finite element simulation. Construction and Building Materials. 2021; 293 ():123522.
Chicago/Turabian StyleCong Du; Pengfei Liu; Kaloyan Ganchev; Guoyang Lu; Markus Oeser. 2021. "Influence of microstructure evolution of bitumen on its micromechanical property by finite element simulation." Construction and Building Materials 293, no. : 123522.
An Artificial Neural Network (ANN)-based back-calculating program combined with a Genetic Algorithm (GA) optimization algorithm was developed for the back-calculation of flexible pavement layer moduli. Deflections measured using geophones on a model pavement structure under accelerated pavement testing (APT) with the MLS30 were utilized for back-calculating the pavement layer moduli. As theoretically expected of visco-elastic materials that are temperature dependent, the back-calculated moduli of the asphaltic layers, namely the surfacing and base, exhibited a decreasing trend with an increase in the temperature and number of APT load cycles. By contrast, the moduli of the unbound base layer and subgrade exhited insensitivity to temperature changes and did not decay significantly as a function of the APT loading. Overall, the integrated GABP algorithm (based ANN formulation) exhibited potential in satisfactorily back-calculating the pavement layer moduli form geophone measured deflections with acceptable accuracy. The splitting fatigue test results show that the fatigue life of asphalt mixture decreases with the increase of loading cycles, which can verify the feasibility of back-calcultion model.
Xiaorui Zhang; Frédéric Otto; Markus Oeser. Pavement moduli back-calculation using artificial neural network and genetic algorithms. Construction and Building Materials 2021, 287, 123026 .
AMA StyleXiaorui Zhang, Frédéric Otto, Markus Oeser. Pavement moduli back-calculation using artificial neural network and genetic algorithms. Construction and Building Materials. 2021; 287 ():123026.
Chicago/Turabian StyleXiaorui Zhang; Frédéric Otto; Markus Oeser. 2021. "Pavement moduli back-calculation using artificial neural network and genetic algorithms." Construction and Building Materials 287, no. : 123026.
Cold-mixed epoxy bitumen (CEB) has been presented as an eco-friendly paving material used for steel bridge deck pavements. This study performed an investigation on three preparation methods of CEBs, which includes one kind of three-component and two kinds of two-component methods. The curing process was characterized through the viscosity measurement. Meanwhile, the microstructure of CEBs was observed using fluorescence microscopy. Mechanical properties of CEBs prepared with different methods were characterized by employing direct tensile tests and dynamic mechanical analysis (DMA). Finally, thermogravimetric analysis (TGA/DTG) was conducted to feature the thermal stability of CEBs. The results indicated that the preparation methods significantly affected the performance of cured CEBs, although the same mix design was adopted. The curing temperature determined the curing rate of CEBs, while the preparation methods dominated the morphological characteristic of cured CEBs. The three-component preparation method can achieve acceptable mechanical performance for engineering requirements. As for two-component methods, the curing agent is supposed to be mixed with bitumen to obtain satisfying microstructures of CEBs.
Quan Liu; Chonghui Wang; Zeyu Zhang; Cong Du; Pengfei Liu; Markus Oeser. Influence of preparation methods on the performance of cold-mixed epoxy bitumen. Materials and Structures 2021, 54, 1 -13.
AMA StyleQuan Liu, Chonghui Wang, Zeyu Zhang, Cong Du, Pengfei Liu, Markus Oeser. Influence of preparation methods on the performance of cold-mixed epoxy bitumen. Materials and Structures. 2021; 54 (2):1-13.
Chicago/Turabian StyleQuan Liu; Chonghui Wang; Zeyu Zhang; Cong Du; Pengfei Liu; Markus Oeser. 2021. "Influence of preparation methods on the performance of cold-mixed epoxy bitumen." Materials and Structures 54, no. 2: 1-13.
The piezoelectric energy harvester (PEH) is a device for recycling wasted mechanical energy from pavements. To evaluate energy collecting efficiency of PEHs with various piezoelectric unit distributions, finite element (FE) models of the PEHs were developed in this study. The PEH was a square of 30 cm × 30 cm with 7 cm in thickness, which was designed according to the contact area between tire and pavement. Within the PEHs, piezoelectric ceramics (PZT-5H) were used as the core piezoelectric units in the PEHs. A total of three distributions of the piezoelectric units were considered, which were 3 × 3, 3 × 4, and 4 × 4, respectively. For each distribution, two diameters of the piezoelectric units were considered to investigate the influence of the cross section area. The electrical potential, total electrical energy and maximum von Mises stress were compared based on the computational results. Due to the non-uniformity of the stress distribution in PEHs, more electrical energy can be generated by more distributions and smaller diameters of the piezoelectric units; meanwhile, more piezoelectric unit distributions cause a higher electrical potential difference between the edge and center positions. For the same distribution, the piezoelectric units with smaller diameter produce higher electrical potential and energy, but also induce higher stress concentration in the piezoelectric units near the edge.
Cong Du; Pengfei Liu; Hailu Yang; Gengfu Jiang; Linbing Wang; Markus Oeser. Finite Element Modeling and Performance Evaluation of Piezoelectric Energy Harvesters with Various Piezoelectric Unit Distributions. Materials 2021, 14, 1405 .
AMA StyleCong Du, Pengfei Liu, Hailu Yang, Gengfu Jiang, Linbing Wang, Markus Oeser. Finite Element Modeling and Performance Evaluation of Piezoelectric Energy Harvesters with Various Piezoelectric Unit Distributions. Materials. 2021; 14 (6):1405.
Chicago/Turabian StyleCong Du; Pengfei Liu; Hailu Yang; Gengfu Jiang; Linbing Wang; Markus Oeser. 2021. "Finite Element Modeling and Performance Evaluation of Piezoelectric Energy Harvesters with Various Piezoelectric Unit Distributions." Materials 14, no. 6: 1405.
The bitumen-aggregate interface is regarded as a significant weak link in asphalt mixtures. Therefore, the fundamental understanding of adhesion between bitumen and aggregate is crucial for designing and preserving asphalt pavement. By far, the molecular dynamics simulation method has notably attracted interest in the characterization of the bitumen-aggregate system. However, the effort towards a reasonable simulation is still ongoing. This study investigated nine cases of bitumen-aggregate systems using molecular dynamic simulations. Specifically, three bitumen binders and three mineral types were considered, respectively. In addition, mineral surface properties and some simulation details were discussed, aiming to obtain a reasonable simulation. The results indicated that polar molecules in bitumen played a vital role in the adhesion between bitumen and aggregates. The mineral surface properties in terms of mineral cleavage surface, surface atomic charge, and surface hydroxylation significantly influenced the simulation results. Accordingly, some simulation tricks were recommended for molecular dynamic simulation of bitumen-aggregate systems: (1) Geometry optimization for the mineral model is not necessary; (2) A vacuum slab with 0 Å should be added on the cleaved surface; (3) Chemical bonds should be deleted after the construction of the bitumen-aggregate system; (4) The Ewald and Atom-based methods are recommended for the energy summation of electrostatic energy and Van der Waals energy, respectively.
Xinyuan Ma; Jiantao Wu; Quan Liu; Weichen Ren; Markus Oeser. Molecular dynamics simulation of the bitumen-aggregate system and the effect of simulation details. Construction and Building Materials 2021, 285, 122886 .
AMA StyleXinyuan Ma, Jiantao Wu, Quan Liu, Weichen Ren, Markus Oeser. Molecular dynamics simulation of the bitumen-aggregate system and the effect of simulation details. Construction and Building Materials. 2021; 285 ():122886.
Chicago/Turabian StyleXinyuan Ma; Jiantao Wu; Quan Liu; Weichen Ren; Markus Oeser. 2021. "Molecular dynamics simulation of the bitumen-aggregate system and the effect of simulation details." Construction and Building Materials 285, no. : 122886.
A locally homogeneous finite element (FE) model is proposed to account for the heterogeneous internal structures of asphalt mixtures in this study. For this model, the internal structure of the asphalt mixture was divided into several homogeneous parts based on digital image processing (DIP) technology. Within each part, one aggregate or air void inclusion was embedded in asphalt mortar, and the integral material properties were homogenized. By comparison with the currently used mesoscale heterogeneous FE models, the proposed locally homogeneous model was proven to be able to effectively consider the local enhancement of the aggregates especially at low frequencies and also consume much less computational time. In addition, the locally homogeneous asphalt mixtures were coupled into the macroscale asphalt pavement model to analyze the load-bearing capacity of the pavements. Comparing with a fully homogeneous pavement model, the computational results showed that the proposed locally homogeneous model can effectively represent the loading-bearing responses of asphalt pavements. This study indicates that this proposed FE simulation approach is able to balance the computational time and simulation effectivity and thus form a base for providing an efficient and robust platform for future development in the multiscale simulation of asphalt pavements.
Cong Du; Pengfei Liu; Quan Liu; Sabine Leischner; Yiren Sun; Jingyun Chen; Markus Oeser. Development of locally homogeneous finite element model for simulating the mesoscale structure of asphalt mixture. Computers & Structures 2021, 248, 106517 .
AMA StyleCong Du, Pengfei Liu, Quan Liu, Sabine Leischner, Yiren Sun, Jingyun Chen, Markus Oeser. Development of locally homogeneous finite element model for simulating the mesoscale structure of asphalt mixture. Computers & Structures. 2021; 248 ():106517.
Chicago/Turabian StyleCong Du; Pengfei Liu; Quan Liu; Sabine Leischner; Yiren Sun; Jingyun Chen; Markus Oeser. 2021. "Development of locally homogeneous finite element model for simulating the mesoscale structure of asphalt mixture." Computers & Structures 248, no. : 106517.
This paper proposes using the master-curve band (MCB) to incorporate the unavoidable measurement errors and modeling uncertainty into the bitumen master-curve construction. In general, the rheological property of bitumen within the linear viscoelastic region is characterized by the master curve of modulus and/or phase angle, provided that the bitumen complies with the time-temperature superposition principle (TTSP). However, the master-curve construction is essentially a mathematical fitting process regardless of whether or not the original data is perfect enough to fit. For this reason, the MCB was introduced to consider the uncertainty information instead of a single master curve. Rheological data of four kinds of bitumen including unaged and aged bitumen were used to construct the MCBs. The results indicated that the generalized sigmoidal model showed the widest master-curve band, followed by Christensen-Anderson-Marasteanu (CAM) and CAM ( G g ) models. The width of MCB was a useful tool to identify the sensitivity of bitumen to rheological models. The sensitivity of bitumen to rheological models is associated with the number of active parameters in rheological models and model parameters’ confidence intervals. The construction of an MCB was beneficial to select the rheological models. Accordingly, the CAM ( G g ) model is proved to be the best to analyze the aging effects.
Quan Liu; Jiantao Wu; Pengfei Zhou; Markus Oeser. The Master-Curve Band considering Measurement and Modeling Uncertainty for Bituminous Materials. Advances in Materials Science and Engineering 2021, 2021, 1 -11.
AMA StyleQuan Liu, Jiantao Wu, Pengfei Zhou, Markus Oeser. The Master-Curve Band considering Measurement and Modeling Uncertainty for Bituminous Materials. Advances in Materials Science and Engineering. 2021; 2021 ():1-11.
Chicago/Turabian StyleQuan Liu; Jiantao Wu; Pengfei Zhou; Markus Oeser. 2021. "The Master-Curve Band considering Measurement and Modeling Uncertainty for Bituminous Materials." Advances in Materials Science and Engineering 2021, no. : 1-11.
For sustainable urban development, the permeable pavement aggressively attracts interests to promote urban water management. This study compared the infiltration and bearing capacities of different permeable pavement structures. To this end, artificial rainfalls with five different intensities were performed on four full-size pavement structures. The infiltration capacity of permeable pavements was estimated based on the runoff curves derived from in-situ measurement. Moreover, their clogging resistance capacity and recovery capacity after maintenance were featured respectively. The Finite Element Method (FEM) was conducted to compare the bearing capacity of four investigated pavement structures. The laboratory results demonstrated the permeability of asphalt mixtures was highly dependent on the water head difference. With regard to the field investigation, it was found that a thicker pavement structure enlarged the infiltration distance, as a result, extending the runoff rising moment and decreasing moment. Besides, a thicker pavement structure can effectively decrease the maximum runoff flow. Furthermore, a reasonable air void combination of multi layers is critical to achieve the optimal permeable performance of the pavement. Multi-layer structure pavement showed superior resistance to the clogging and recovery capacity under maintenance due to the existence of a clogging buffer area.
Quan Liu; Sufang Liu; Gaohui Hu; Tao Yang; Cong Du; Markus Oeser. Infiltration Capacity and Structural Analysis of Permeable Pavements for Sustainable Urban: A Full-scale Case Study. Journal of Cleaner Production 2020, 288, 125111 .
AMA StyleQuan Liu, Sufang Liu, Gaohui Hu, Tao Yang, Cong Du, Markus Oeser. Infiltration Capacity and Structural Analysis of Permeable Pavements for Sustainable Urban: A Full-scale Case Study. Journal of Cleaner Production. 2020; 288 ():125111.
Chicago/Turabian StyleQuan Liu; Sufang Liu; Gaohui Hu; Tao Yang; Cong Du; Markus Oeser. 2020. "Infiltration Capacity and Structural Analysis of Permeable Pavements for Sustainable Urban: A Full-scale Case Study." Journal of Cleaner Production 288, no. : 125111.
To reduce the thermal-oxidative aging of asphalt and the release amount of harmful volatiles during the construction of asphalt pavement, a new composite anti-aging agent was developed. Since the volatiles were mainly released from saturates and aromatics during the thermal-oxidative aging of asphalt, expanded graphite (EG) was selected as a stabilizing agent to load magnesium hydroxide (MH) and calcium carbonate (CaCO3) nanoparticles for preparing the anti-aging agents of saturates and aromatics, respectively. Thermal stability and volatile constituents released from saturates and aromatics before and after the thermal-oxidative aging were characterized using the isothermal Thermogravimetry/Differential Scanning Calorimetry-Fourier Transform Infrared Spectrometer test (TG/DSC-FTIR test). Test results indicate that anti-aging agents of EG/MH and EG/CaCO3 effectively inhibit the volatilization of light components in asphalt and improve the thermal stability of saturates and aromatics. Then, the proportions of EG, MH, and CaCO3 added in the developed composite anti-aging agent of EG/MH/CaCO3 are 2:1:3 by weight. EG/MH/CaCO3 plays a synergetic effect on inhibiting the thermal-oxidative aging of asphalt, and reduces the release amount of harmful volatiles during the thermal-oxidative aging after EG/MH/CaCO3 is added into asphalt at the proposed content of 10 wt.%. EG plays a synergistic role with MH and CaCO3 nanoparticles to prevent the chain reactions, inhibiting the thermal-oxidative aging of asphalt.
Zhihui Hu; Tao Xu; Pengfei Liu; Markus Oeser; HaoPeng Wang. Improvements of Developed Graphite Based Composite Anti-Aging Agent on Thermal Aging Properties of Asphalt. Materials 2020, 13, 4005 .
AMA StyleZhihui Hu, Tao Xu, Pengfei Liu, Markus Oeser, HaoPeng Wang. Improvements of Developed Graphite Based Composite Anti-Aging Agent on Thermal Aging Properties of Asphalt. Materials. 2020; 13 (18):4005.
Chicago/Turabian StyleZhihui Hu; Tao Xu; Pengfei Liu; Markus Oeser; HaoPeng Wang. 2020. "Improvements of Developed Graphite Based Composite Anti-Aging Agent on Thermal Aging Properties of Asphalt." Materials 13, no. 18: 4005.
In order to further understand the shape memory mechanism of a silicon dioxide/shape memory polyurethane (SiO2/SMPU) composite, the thermodynamic properties and shape memory behaviors of prepared SiO2/SMPU were characterized. Dynamic changes in the molecular orientation and interphase structures of SiO2/SMPU during a shape memory cycle were then discussed according to the small angle X-ray scattering theory, Guinier’s law, Porod approximation, and fractal dimension theorem. In this paper, a dynamic mechanical analyzer (DMA) helped to determine the glass transition start temperature (Tg) by taking the onset point of the sigmoidal change in the storage modulus, while transition temperature (Ttrans) was defined by the peak of tan δ, then the test and the calculated results indicated that the Tg of SiO2/SMPU was 50.4 °C, and the Ttrans of SiO2/SMPU was 72.18 °C. SiO2/SMPU showed good shape memory performance. The programmed SiO2/SMPU showed quite obvious microphase separation and molecular orientation. Large-size sheets and long-period structures were formed in the programmed SiO2/SMPU, which increases the electron density difference. Furthermore, some hard segments had been rearranged, and their gyration radii decreased. In addition, several defects formed at the interfaces of SiO2/SMPU, which caused the generation of space charges, thus leading to local electron density fluctuations. The blurred interphase structure and the intermediate layer formed in the programmed SiO2/SMPU and there was evident crystal damage and chemical bond breakage in the recovered SiO2/SMPU. Finally, the original and recovered SiO2/SMPU samples belong to the surface fractal system, but the programmed sample belongs to the mass fractal and reforms two-phase structures. This study provides an insight into the shape memory mechanism of the SiO2/SMPU composite.
Shuang Shi; Tao Xu; Dawei Wang; Markus Oeser. The Difference in Molecular Orientation and Interphase Structure of SiO2/Shape Memory Polyurethane in Original, Programmed and Recovered States during Shape Memory Process. Polymers 2020, 12, 1994 .
AMA StyleShuang Shi, Tao Xu, Dawei Wang, Markus Oeser. The Difference in Molecular Orientation and Interphase Structure of SiO2/Shape Memory Polyurethane in Original, Programmed and Recovered States during Shape Memory Process. Polymers. 2020; 12 (9):1994.
Chicago/Turabian StyleShuang Shi; Tao Xu; Dawei Wang; Markus Oeser. 2020. "The Difference in Molecular Orientation and Interphase Structure of SiO2/Shape Memory Polyurethane in Original, Programmed and Recovered States during Shape Memory Process." Polymers 12, no. 9: 1994.
This study aims to understand the damage evolution of water-saturated asphalt mixture under freeze-thaw cyclic loading from the perspective of continuum damage mechanics (CDM). The connective void content of three types of asphalt mixtures was employed to characterize the damage to the corresponding asphalt mixture sample under freeze-thaw cyclic loading. The variation of connective void content revealed the nonlinear characteristics of asphalt mixture damage accumulation. A CDM-based model was built to describe the damage evolution law of asphalt mixture. The results predicted by this model agreed with the experimental data, validating its feasibility.
Zeyu Zhang; Quan Liu; Qi Wu; Huining Xu; Pengfei Liu; Markus Oeser. Damage evolution of asphalt mixture under freeze-thaw cyclic loading from a mechanical perspective. International Journal of Fatigue 2020, 142, 105923 .
AMA StyleZeyu Zhang, Quan Liu, Qi Wu, Huining Xu, Pengfei Liu, Markus Oeser. Damage evolution of asphalt mixture under freeze-thaw cyclic loading from a mechanical perspective. International Journal of Fatigue. 2020; 142 ():105923.
Chicago/Turabian StyleZeyu Zhang; Quan Liu; Qi Wu; Huining Xu; Pengfei Liu; Markus Oeser. 2020. "Damage evolution of asphalt mixture under freeze-thaw cyclic loading from a mechanical perspective." International Journal of Fatigue 142, no. : 105923.
The dynamic Shear Rheometer (DSR) test is a standard method used to characterize the rheological properties of bitumen binders. Prior research substantiates the belief that, given that measured results are dependent on the rheometer gap size, currently recommended rheometer gap sizes (1 mm/2mm) cannot represent the mechanical properties of bitumen in asphalt mixtures. This study focused on the effect of gap size on the rheological property of bitumen binders. To this end, three bitumen binders were measured at different rheometer gap sizes (10 ~ 1000 μm). Subsequently, the rheological properties, including the complex modulus, phase angle, master curve, black diagram, were discussed. The results indicated that the measured rheological properties of bitumen binders are related to the testing gap size. In particular, as the gap size decreases, the complex modulus tends to decrease. Due to the presence of modifiers, the effect of the rheometer gap size also depends on the type of bitumen. The selective adsorption and colloidal theories were introduced to understand the effect of gap size. Additionally, a mathematical relationship called Temperature-Gap Superposition Principle (TGSP) was proposed to establish the relationship between the measured complex moduli in the standard state and the thin state.
Quan Liu; Jiantao Wu; Xin Qu; Chonghui Wang; Markus Oeser. Investigation of bitumen rheological properties measured at different rheometer gap sizes. Construction and Building Materials 2020, 265, 120287 .
AMA StyleQuan Liu, Jiantao Wu, Xin Qu, Chonghui Wang, Markus Oeser. Investigation of bitumen rheological properties measured at different rheometer gap sizes. Construction and Building Materials. 2020; 265 ():120287.
Chicago/Turabian StyleQuan Liu; Jiantao Wu; Xin Qu; Chonghui Wang; Markus Oeser. 2020. "Investigation of bitumen rheological properties measured at different rheometer gap sizes." Construction and Building Materials 265, no. : 120287.
Emulsified asphalt (EA) is an environment-friendly paving material that is commonly used as the binder of the interlay stress-absorbing composite (ISAC) layer. Roughening the surface of glass fiber by chemical treating is an effective approach to improve the adhesion between glass fiber and EA. However, the effects of the fiber treatment method on the performance of fiber-reinforced EA (FEA) still remain unclear. In this study, glass fiber, which is commonly used in the ISAC layer, was firstly treated with six methods (three etchants in two concentrations). Fibers were then incorporated into EA to prepare FEA samples. Finally, laboratory tests, including Scanning electron microscope (SEM) test, Fourier-transform infrared spectroscopy (FTIR) test, contact angle test, surface tension test, dynamic shear rheometer (DSR) test, and direct tensile test, were performed to evaluate the changes in the physical and chemical properties of glass fiber, EA, and FEA. The experimental results indicated that etching roughened the surface of glass fiber, increased the adhesion work of EA-glass fiber and the fracture strength of FEA. In addition, it was found that the interaction between glass fiber and EA was physical bonding and the performance of FEAs depended on the glass fiber treatment method. Sulfuric acid with a concentration of 2 mol/L was recommended as the optimal glass fiber etchant.
Yanyan Liu; Zeyu Zhang; Lijuan Tan; Yong Xu; Chonghui Wang; Pengfei Liu; Huayang Yu; Markus Oeser. Laboratory evaluation of emulsified asphalt reinforced with glass fiber treated with different methods. Journal of Cleaner Production 2020, 274, 123116 .
AMA StyleYanyan Liu, Zeyu Zhang, Lijuan Tan, Yong Xu, Chonghui Wang, Pengfei Liu, Huayang Yu, Markus Oeser. Laboratory evaluation of emulsified asphalt reinforced with glass fiber treated with different methods. Journal of Cleaner Production. 2020; 274 ():123116.
Chicago/Turabian StyleYanyan Liu; Zeyu Zhang; Lijuan Tan; Yong Xu; Chonghui Wang; Pengfei Liu; Huayang Yu; Markus Oeser. 2020. "Laboratory evaluation of emulsified asphalt reinforced with glass fiber treated with different methods." Journal of Cleaner Production 274, no. : 123116.
A polyurethane-based rubber-modified layer within a road superstructure leads to absorption of traffic emissions. Noise emissions have quite a negative effect on society, as they lead to high stress levels and health risks for people. Therefore, constructional methods of noise-reducing road layers have been developed before. This research paper focuses on the questions whether the existing noise-reducing road constructions, which have a low durability, can be optimized in terms of a longer duration while simultaneously maintaining the noise-reducing effects. Within this research, a large parametric study contributed to an optimal solution of a noise-reducing and durable layer. We found that noise absorption is mainly dependent of the void content of the pavement and its flexibility. Also, a result is that the durability of a road layer is based on the properties of the binder as well as the composition of the mixture, i.e., the grading curve. As we used polyurethane binders within our mixtures, which have a low dependency on regular environmental temperatures after their complete chemical reaction, we can imply a low temperature dependence of the entire polyurethane asphalt mixture. Based on these results, the construction of a noise-reducing and durable road layer is a great solution. The application of such road layers leads to lower traffic emissions at major hotspots. These might be urban highways, where the infrastructure is too tight to build noise barriers, enclosures or tunnels.
Sabine Faßbender; Markus Oeser. Investigation on an Absorbing Layer Suitable for a Noise-Reducing Two-Layer Pavement. Materials 2020, 13, 1235 .
AMA StyleSabine Faßbender, Markus Oeser. Investigation on an Absorbing Layer Suitable for a Noise-Reducing Two-Layer Pavement. Materials. 2020; 13 (5):1235.
Chicago/Turabian StyleSabine Faßbender; Markus Oeser. 2020. "Investigation on an Absorbing Layer Suitable for a Noise-Reducing Two-Layer Pavement." Materials 13, no. 5: 1235.
Angularity and surface texture of aggregates are important morphological characteristics, which have significant effects on the micromechanical responses of asphalt composites. A novel approach to quantify and classify the complexity of aggregate angularity and surface texture is proposed from a statistical perspective in this study. The methodology consists of three main steps, as follows: 1) the aggregate is three-dimensional (3D) reconstructed, and the model surface is triangulated into facets to conduct clustering for aggregate angles evaluation; 2) consequently, a reference plane is determined for each facet cluster to quantify the surface texture of a surface area which overlaps the cluster, and thus the surface texture is quantified; and 3) aggregates are classified by using the distribution characteristics of the angularity and surface texture respectively. Based on the quantification with the presented approach, 275 grains were classified by the angularity and surface texture. Results indicate the benefit of the proposed method in accurate quantification and classification of aggregate angularity and surface texture, which facilitate the bridging of the gap between aggregate morphology and micromechanical performance of asphalt composites.
Can Jin; Feilong Zou; Xu Yang; Kai Liu; Pengfei Liu; Markus Oeser. Three-dimensional quantification and classification approach for angularity and surface texture based on surface triangulation of reconstructed aggregates. Construction and Building Materials 2020, 246, 118120 .
AMA StyleCan Jin, Feilong Zou, Xu Yang, Kai Liu, Pengfei Liu, Markus Oeser. Three-dimensional quantification and classification approach for angularity and surface texture based on surface triangulation of reconstructed aggregates. Construction and Building Materials. 2020; 246 ():118120.
Chicago/Turabian StyleCan Jin; Feilong Zou; Xu Yang; Kai Liu; Pengfei Liu; Markus Oeser. 2020. "Three-dimensional quantification and classification approach for angularity and surface texture based on surface triangulation of reconstructed aggregates." Construction and Building Materials 246, no. : 118120.