Computation of Elastic Properties of Portland Cement Using Molecular Dynamics

Wu, Weidong; Al‐Ostaz, Ahmed; Cheng, Alexander H.‐D.; Song, Chung R.

doi:10.1061/(asce)nm.2153-5477.0000026

Cited by 48 publications

(31 citation statements)

References 25 publications

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“…The isotropic bulk and shear modulus of each component were calculated from the stiffness constants presented in Table 2 following the Voigt-Reuss-Hill approximation. These elastic properties values of each individual phase are in agreement with data reported from computational and experimental studies [29,30,33,34,[55][56][57] and are shown in Table 4 K…”

Section: Parametrization Of the Molecular Dynamics (Md)supporting

confidence: 90%

“…The present work proposes and presents a novel method to study the constitutive mechanical properties and understand characteristics of cement paste modeled as a molecular system formed by a combination of hydrated and unhydrated material chemistry phases, using molecular dynamics simulations. Prior work has primarily reported only such constitutive material predictions of individual single molecular phases for this cement paste composite system [28][29][30][31][32][33][34][35]. Characteristics and properties of CSH phase are considered to be one of the most dominant factors influencing the behavior of cement paste.…”

Section: Introductionmentioning

confidence: 99%

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Constitutive Stiffness Characteristics of Cement Paste as a Multiphase Composite System—A Molecular Dynamics-Based Model

Espinosa

Hodo

Murillo

et al. 2017

Journal of Engineering Materials and Technology

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Cement paste is a material with heterogeneous composite structure consisting of hydrated and unhydrated phases at all length scales that varies depending upon the degree of hydration. In this paper, a method to model cement paste as a multiphase system at molecular level for predicting constitutive properties and for understanding the constitutive mechanical behavior characteristics using molecular dynamics is presented. The proposed method creates a framework for molecular level models suitable for predicting constitutive properties of heterogeneous cement paste that could provide potential for comparisons with low length scale experimental characterization techniques. The molecular modeling method followed two approaches: one involving admixed molecular phases and the second involving clusters of the individual phases. In particular, in the present study, cement paste is represented as two-phase composite systems consisting of the calcium silicate hydrate (CSH) phase combined with unhydrated phases tricalcium silicate (C3S) or dicalcium silicate (C2S). Predicted elastic stiffness constants based on molecular model representations employed for the two phases showed that, although the individual phases have anisotropic characteristics, the composite system behaves as an isotropic material. The isotropic characteristics seen from two-phase molecular models mimic the isotropic material nature of heterogeneous cement paste at engineering scale. Further, predicted bulk modulus of the composite system based on molecular modeling is found to be high compared to the elastic modulus, which concurs with the high compression strength of cement paste seen at engineering length scales.

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Section: Parametrization Of the Molecular Dynamics (Md)supporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Constitutive Stiffness Characteristics of Cement Paste as a Multiphase Composite System—A Molecular Dynamics-Based Model

Espinosa

Hodo

Murillo

et al. 2017

Journal of Engineering Materials and Technology

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show abstract

“…In order to understand the chemical reactions in C-S-H, many researches have previously tried to characterize the structure of C-S-H gel at the atomistic level [17][18][19][20][21] . In that regard, different strategies were utilized to model the atomistic structure of C-S-H in order to understand its nanostructure properties 22,23 . Bauchy et al…”

Section: Introductionmentioning

confidence: 99%

Nanostructural Characteristics and Interfacial Properties of Polymer Fibers in Cement Matrix

Shalchy

Rahbar

2015

ACS Appl. Mater. Interfaces

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Concrete is the most used material in the world. It is also one of the most versatile yet complex materials that humans have used for construction. However, an important weakness of concrete (cement-based composites) is its low tensile properties. Therefore, over the past 30 years many studies were focused on improving its tensile properties using a variety of physical and chemical methods. One of the most successful attempts is to use polymer fibers in the structure of concrete to obtain a composite with high tensile strength and ductility. The advantages of polymer fiber as reinforcing material in concrete, both with regard to reducing environmental pollution and the positive effects on a country's economy, are beyond dispute. However, a thorough understanding of the mechanical behavior of fiber-reinforced concrete requires a knowledge of fiber/matrix interfaces at the nanoscale. In this study, a combination of atomistic simulations and experimental techniques has been used to study the nanostructure of fiber/matrix interfaces. A new model for calcium-silicate-hydrate (C-S-H)/fiber interfaces is also proposed on the basis of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) analyses. Finally, the adhesion energy between the C-S-H gel and three different polymeric fibers (poly(vinyl alcohol), nylon-6, and polypropylene) were numerically studied at the atomistic level because adhesion plays a key role in the design of ductile fiber-reinforced composites. The mechanisms of adhesion as a function of the nanostructure of fiber/matrix interfaces are further studied and discussed. It is observed that the functional group in the structure of polymer macromolecule affects the adhesion energy primarily by changing the C/S ratio of the C-S-H at the interface and by absorbing additional positive ions in the C-S-H structure.

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“…136, JANUARY 2014 Transactions of the ASME macroscale mechanical behavior of cementitious materials; the properties need to be determined at the microlength scales. In recent years there has been an intensive research activity devoted to describing the cementitious materials by computational means [10,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]. At the microlevel the representative volume approach is widely used due to the flexibility and applicability of this method to various physical processes at the microscale, such as chemical kinetics, electrical and thermal conductivity, as well as linear and nonlinear elastic properties.…”

Section: Representative Volume Elementmentioning

confidence: 99%

Representative Volume Element Based Modeling of Cementitious Materials

Shahzamanian

Tadepalli

Rajendran

et al. 2013

Journal of Engineering Materials and Technology

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The current work focuses on evaluation of the effective elastic properties of cementitious materials through a voxel based finite element analysis (FEA) approach. Voxels are generated for a heterogeneous cementitious material (type-I cement) consisting of typical volume fractions of various constituent phases from digital microstructures. The microstructure is modeled as a microscale representative volume element (RVE) in ABAQUS V R to generate cubes several tens of microns in dimension and subjected to various prescribed deformation modes to generate the effective elastic tensor of the material. The RVE-calculated elastic properties such as moduli and Poisson's ratio are validated through an asymptotic expansion homogenization (AEH) and compared with rule of mixtures. Both periodic (PBC) and kinematic boundary conditions (KBC) are investigated to determine if the elastic properties are invariant due to boundary conditions. In addition, the method of "Windowing" was used to assess the randomness of the constituents and to validate how the isotropic elastic properties were determined. The average elastic properties obtained from the displacement based FEA of various locally anisotropic microsize cubes extracted from an RVE of size 100 Â 100 Â 100 lm showed that the overall RVE response was fully isotropic. The effects of domain size, degree of hydration (DOH), kinematic and periodic boundary conditions, domain sampling techniques, local anisotropy, particle size distribution (PSD), and random microstructure on elastic properties are studied.

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Computation of Elastic Properties of Portland Cement Using Molecular Dynamics

Cited by 48 publications

References 25 publications

Constitutive Stiffness Characteristics of Cement Paste as a Multiphase Composite System—A Molecular Dynamics-Based Model

Constitutive Stiffness Characteristics of Cement Paste as a Multiphase Composite System—A Molecular Dynamics-Based Model

Nanostructural Characteristics and Interfacial Properties of Polymer Fibers in Cement Matrix

Representative Volume Element Based Modeling of Cementitious Materials

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