Piezoelectric response and failure behavior of cement paste under external loading

Laanaiya, M.; Zaoui, A.

doi:10.1016/j.cemconres.2020.106257

Cited by 7 publications

(1 citation statement)

References 35 publications

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“…It includes the bond formation energy, the Coulombic contribution, the vdW energy, the angular and torsional energy, the lone pair energy, and finally the energy penalty for under/over coordination stability of atoms. This force field has been applied successfully on geopolymer, calcium silicate hydrates, sodium aluminosilicate glass, silica, zeolite, and clay minerals …”

Section: Methods and Computational Modelsmentioning

confidence: 99%

Theoretical Studies of Adsorption Reactions of Aluminosilicate Aqueous Species on Graphene-Based Nanomaterials: Implications for Geopolymer Binders

Izadifar,

Sekkal,

Dubyey

et al. 2023

ACS Appl. Nano Mater.

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Geopolymer nanocomposites incorporating carbon nanotube (CNT)/graphene-based nanomaterials have become an exciting area of research because of their exceptional interface compatibility, providing improved mechanical, electrical, and thermal properties for next-generation construction materials. Accordingly, geopolymers are superior candidates for the implementation of graphene-based nanocomposites. In this paper, a comprehensive examination through equilibrium density functional theory (DFT) with and without the contribution of van der Waals (vdW) dispersion interaction, along with ReaxFF molecular dynamics (ReaxFF-MD) computational modeling approaches, was carried out to comprehend the interaction mechanisms and adsorption energies between graphene-based nanosheets and primary aqueous species of geopolymer structure. Results showed that the interaction of Si(OH)4 aqueous species with the pristine graphene substrate has the weakest physical binding adsorption. The adsorption energy of silicate species on the pristine graphene substrate increased when involving interactions with sodium or potassium cations. Graphene-based nanomaterial surface functionalization with hydroxyl or carboxyl groups led to the higher adsorption energies of silicate and aluminate species due to the stronger electrostatic interaction. Computations also revealed that Na+, compared to K+, mostly increased the interfacial binding between the geopolymer and CNT/graphene-based nanomaterials. The computed MD results exhibited some qualitative agreement with ab initio calculations (at 0 K), with an overestimation tendency as expected due to the contribution of kinetic energy at 300 K. DFT results refute literature assumptions of a covalent oxo-bridging bond between silicon and carbon atoms, confirming electrostatic interactions (Coulomb interaction), with van der Waals (vdW) dispersion forces also playing a significant role in adsorption energy. Our study provides a systematic quantification of missing binding energy parameters and their implications for upscaling interface effects to the nanocomposite level.

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Section: Methods and Computational Modelsmentioning

confidence: 99%

Theoretical Studies of Adsorption Reactions of Aluminosilicate Aqueous Species on Graphene-Based Nanomaterials: Implications for Geopolymer Binders

Izadifar,

Sekkal,

Dubyey

et al. 2023

ACS Appl. Nano Mater.

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Residual water and interfacial bonding effects on the mechanical performance of CNT/fly ash geopolymer binder

Sekkal,

Zaoui

2024

Structural Concrete

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Nowadays, geopolymers are advanced alternatives to cementitious materials, where their excellent chemical and fire resistance are some of its most appealing properties. Fly ash geopolymers enable the use of industrial waste materials while converting them into a novel binding material. Their production is accompanied by a much lower CO2 emission when compared to Portland cement. Reinforcing fly ash geopolymers with carbon nanotubes would significantly strengthen its microstructure and with this enhancing the long‐term mechanical and durability performance. The aim of this work is to use reactive molecular dynamics simulation method to optimize the mechanical properties of fly ash geopolymers with nano‐reinforced carbon nanotubes (CNTs). During this study, the impact of humidity and interfacial bonding strength between carbon nanotube and geopolymer is investigated. Our findings show that structural transformations under hydration process comes from the weakening of AlO bond, leading to the elongation of AlO and NaOH bonds, forming aluminum and sodium hydroxyls. Conversely, silicate is not sensitive to water and exhibits hydrophobic behavior. In addition, our results show that there is an optimal value of water content (7.17 wt.%) that makes the geopolymer nanostructure strengthen. The related elastic modulus rises by 21.56%, 20.60%, and 18.41% for Si/Al ratio of 1, 2, and 3, respectively. Inserting carbon nanofillers to fly ash nanostructure has remarkably shown an interesting strength enhancement. More precisely, when interfacial bonding concentration is around 19.36%, it is observed a positively increasing of the compressive strength, shear, indentation and elastic modulus with 39%, 65.2%, 72.3%, and 144.85%, respectively. Reduced density gradient supports that the interaction between carbon nanotube and fly ash geopolymer is dominated by a van der Waals one.

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Wettability and work of adhesion of water nanodroplet on (001) surface of cement paste

Zhu

Zaoui²,

Sekkal³

2022

Cement and Concrete Research

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Piezoelectric response and failure behavior of cement paste under external loading

Cited by 7 publications

References 35 publications

Theoretical Studies of Adsorption Reactions of Aluminosilicate Aqueous Species on Graphene-Based Nanomaterials: Implications for Geopolymer Binders

Theoretical Studies of Adsorption Reactions of Aluminosilicate Aqueous Species on Graphene-Based Nanomaterials: Implications for Geopolymer Binders

Residual water and interfacial bonding effects on the mechanical performance of CNT/fly ash geopolymer binder

Wettability and work of adhesion of water nanodroplet on (001) surface of cement paste

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