scholarly journals Research on the Mechanism of Surfactant Warm Mix Asphalt Additive-Based on Molecular Dynamics Simulation

Coatings ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1303
Author(s):  
Pinhui Zhao ◽  
Mingliang Dong ◽  
Yansheng Yang ◽  
Jingtao Shi ◽  
Junjie Wang ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Shear Rate ◽  
Asphalt Binder ◽  
Warm Mix Asphalt ◽  
Dynamics Simulation ◽  
Stone Surface ◽  
Lubricating Film ◽  
Lubrication Performance ◽  
Shear Friction

Warm mix asphalt (WMA) technology can bring certain environmental and technical benefits through reducing the temperature of production, paving, and compaction of mixture asphalt. Recent studies have shown that some WMA additives are able to reduce the temperature by increasing the lubricating properties of asphalt binder.-based on the tribological theory, this paper studied the mechanism of adsorbing and lubricating film of base asphalt and WMA on the surface of stone by molecular dynamics (MD) simulation method, and the effect of surfactant WMA additive on the lubrication performance of the shear friction system of “stone–asphalt–stone”. The model of base asphalt lubricating film, including saturates, aromatics, resin and asphaltene, as well as the model of warm mix asphalt lubricating film containing imidazoline-type surfactant WMA (IMDL WMA) additive molecule, were established. The shear friction system of “stone–asphalt–stone” of base asphalt and warm mix asphalt was built on the basis of an asphalt lubrication film model and representative calcite model. The results show that the addition of IMDL WMA additive can effectively improve the lubricity of asphalt, reduce the shear stress of asphalt lubricating film, and increase the stability of asphalt film. The temperature in the WMA lubricating film rises, while the adsorption energy on the stone surface decreases with the increase of shear rate, indicating that the higher the shear rate is, the more unfavorable it is for the WMA lubricating film to wrap on the stone surface. In addition, the shear stress of the WMA lubricating film decreased with increasing temperature, while the shear stress of the base asphalt lubricating film increased first and then decreased, demonstrating that the compactability of the asphalt mixture did not improve linearly with the increase of temperature.

scholarly journals Shear-rate dependence of thermodynamic properties of the Lennard-Jones truncated and shifted fluid by molecular dynamics simulations

2021 ◽  
Author(s):  
Martin P. Lautenschlaeger ◽  
Hans Hasse
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Shear Rate ◽  
Molecular Dynamics Simulations ◽  
Local Structure ◽  
Rate Dependence ◽  
Lennard Jones ◽  
Fluid Properties ◽  
Dynamics Simulations ◽  
Shear Rate Dependence

It was shown recently that using the two-gradient method, thermal, caloric, and transport properties of fluids under quasi-equilibrium conditions can be determined simultaneously from nonequilibrium molecular dynamics simulations. It is shown here that the influence of shear stresses on these properties can also be studied using the same method. The studied fluid is described by the Lennard-Jones truncated and shifted potential with the cut-off radius r*c = 2.5σ. For a given temperature T and density ρ, the influence of the shear rate on the following fluid properties is determined: pressure p, internal energy u, enthalpy h, isobaric heat capacity cp, thermal expansion coefficient αp, shear viscosity η, and self-diffusion coefficient D. Data for 27 state points in the range of T ∈ [0.7, 8.0] and ρ ∈ [0.3, 1.0] are reported for five different shear rates (γ ̇ ∈ [0.1,1.0]). Correlations for all properties are provided and compared with literature data. An influence of the shear stress on the fluid properties was found only for states with low temperature and high density. The shear-rate dependence is caused by changes in the local structure of the fluid which were also investigated in the present work. A criterion for identifying the regions in which a given shear stress has an influence on the fluid properties was developed. It is based on information on the local structure of the fluid. For the self-diffusivity, shear-induced anisotropic effects were observed and are discussed.

RELATION OF LAMELLAR STRUCTURE AND SHEAR STRESS OF DYNAMIC PM-ER FLUIDS

2011 ◽  
Vol 25 (07) ◽  
pp. 971-977 ◽  
Author(s):  
D. K. LIU ◽  
C. LI ◽  
J. YAO ◽  
L. W. ZHOU ◽  
J. P. HUANG
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Lamellar Structure ◽  
Inverse Correlation ◽  
Dynamics Simulation ◽  
Rheological Characteristics ◽  
Lamellar Structures ◽  
Dynamic Rheological Behavior ◽  
Moving Particle ◽  
Er Fluids

To understand the dynamic rheological behavior of polar molecular electrorheological (PMER) fluids, the shear stress and viscosity of the colloids are compared with the parameters of their lamellar structures which are obtained simultaneously with the rheological characteristics using an electrorheoscope. The results of the experiments and molecular dynamics simulation indicate that the shear stress is mainly contributed by the moving particle rings, and there is an inverse correlation between the width of the moving particle rings and the shear stress.

Experimental study and molecular dynamics simulation of wall slip in a micro-extrusion flowing process

2011 ◽  
Vol 225 (5) ◽  
pp. 1175-1190 ◽  
Author(s):  
D Zhao ◽  
Y Jin ◽  
M Wang ◽  
M Song
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Slip Velocity ◽  
Polymer Melts ◽  
Critical Shear Stress ◽  
Wall Slip ◽  
Dynamics Simulation ◽  
Desorption Mechanism ◽  
Adsorption Desorption

Wall slip is one of the most important characteristics of polymer melts’ elasticity behaviours as well as the most significant factor which affects the flow of polymer melts. Based on the traditional Mooney method, through a double-barrel capillary rheometer, the relationship between velocities of wall slip, shear stress, shear rate, diameters of dies, and temperature of polypropylene (PP), high-density polyethylene (HDPE), polystyrene (PS), and polymethylmethacrylate (PMMA) is explored. The results indicate that the velocities of the wall slip of PP and HDPE increase apparently with shear stress and slightly with temperature. Meanwhile, the rise of temperature results in the decrease of critical shear stress. The wall-slip velocities of PS and PMMA are negative which means that the Mooney method based on the adsorption–desorption mechanism has determinate limitation to calculate the wall-slip velocity. Based on the entanglement–disentanglement mechanism, a new wall-slip model is built. With the new model, the calculation values of velocity of PP and HDPE correspond to the experimental values very well and the velocities of PS and PMMA are positive. The velocities of PS and PMMA increase obviously with the rise of shear stress. The rise of temperature results in the increase of velocity and decrease of critical shear stress. Then, the molecular dynamics simulation is used to investigate the combining energy between four polymer melts and the inside wall. The results show that at the given temperature and pressure, the molecules of PS and PMMA combine with atoms of the wall more tightly than those of PP and HDPE which means when wall slip occurs, the molecules of PS and PMMA near the wall will adsorb to the surface of the wall. However, those of PP and HDPE will be easy to slip. Therefore, the wall-slip mechanism of PP and HDPE is the adsorption–desorption mechanism, and that of PS and PMMA is the entanglement–disentanglement mechanism. According to the different wall-slip mechanisms of four polymers, an all-sided calculation method of wall-slip velocity is raised which consummates the theory of wall slip of polymer melts.

Molecular Dynamics Simulation to Investigate the Adhesion and Diffusion of Asphalt Binder on Aggregate Surfaces

2019 ◽  
Vol 2673 (4) ◽  
pp. 500-512 ◽  
Author(s):  
Zhao Du ◽  
Xingyi Zhu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Asphalt Binder ◽  
Asphalt Mixture ◽  
Dynamics Simulation ◽  
Main Role ◽  
Mineral Surfaces ◽  
Mineral Surface ◽  
And Diffusion ◽  
Mineral Aggregates

Asphalt-aggregate interface properties are considered to play a crucial role in asphalt mixture. To better understand the detailed binding mechanism, the present study analyzed the adhesion and diffusion of asphalt binder on mineral surfaces at a nanoscale based on molecular dynamics simulation. A 12-component AAA-1 asphalt model and five oxide models were generated to represent asphalt binder and mineral aggregates, respectively. The effectiveness of these models was validated by comparing the physical properties of the model with the values reported in the literature. The binding energy and diffusion coefficient obtained were examined to characterize the adhesion and diffusion of asphalt on different mineral surfaces. The results indicated that van der Waals energy played the main role in forming the strong physisorption of asphalt on the mineral surface. Among all four fractions of asphalt, asphaltene made a great contribution to the adhesion of asphalt on the mineral surface. It was also found that the work of adhesion between asphalt and five oxides ranked MgO > CaO > Al2O3 > Fe2O3 > SiO2. The content of MgO and CaO in mineral aggregates can be further adopted as an index to evaluate and classify mineral aggregates during asphalt mixture design. Meanwhile, asphalt mobility does not entirely rely on the molecular mass but also depends strongly on the medium it adsorbed into and interaction energy. This work provides a fundamental understanding of the adhesion and diffusion of asphalt binder on the mineral aggregate surface at the atomistic scale.

Investigating the interaction behavior between asphalt binder and rubber in rubber asphalt by molecular dynamics simulation

2020 ◽  
Vol 252 ◽  
pp. 118956 ◽  
Author(s):  
Fucheng Guo ◽  
Jiupeng Zhang ◽  
Jianzhong Pei ◽  
Bochao Zhou ◽  
Augusto Cannone Falchetto ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Asphalt Binder ◽  
Dynamics Simulation ◽  
Interaction Behavior

Theoretical Study on the Interaction between Shuffle 60° Dislocation and Hexavacancy in Silicon

2012 ◽  
Vol 602-604 ◽  
pp. 861-865
Author(s):  
Kang You Zhong ◽  
Qing Yuan Meng ◽  
Zhi Fu Yang
Keyword(s):  
Molecular Dynamics ◽  
Shear Stress ◽  
Molecular Dynamics Simulation ◽  
Linear Relationship ◽  
Critical Stress ◽  
Theoretical Study ◽  
Dynamics Simulation ◽  
Regular Chain ◽  
Critical Resolved Shear Stress ◽  
Weber Potential

The interaction of the shuffle 60° dislocation with a regular chain of hexavacancies was investigated via the molecular dynamics simulation with Stillinger-Weber potential. The results show that an attraction exists between the shuffle 60° dislocation and hexavacany. The attraction energy is dependent obviously upon the hexavacancy concentration. The dislocation can overcome the pinning of vacancies under a critical resolved shear stress, and a linear relationship is found between the critical stress and hexavacancy concentration.

Sign in / Sign up

Export Citation Format

Share Document