Evaluation of the dispersion of metakaolin–graphene oxide hybrid in water and cement pore solution: can metakaolin really improve the dispersion of graphene oxide in the calcium-rich environment of hydrating cement matrix?

Amini, Kasra; Amiri, Soroush; Ghasemi, Ali; Mirvalad, Sajjad; Korayem, Asghar Habibnejad

doi:10.1039/d1ra01504d

Cited by 16 publications

(3 citation statements)

References 63 publications

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“…In recent decades, nanotechnology as an alternative has attracted the attention of researchers for improving the properties of cementitious composites. The literature shows that the incorporation of nanoparticles, such as nano-TiO 2 , , carbon nanotube, − and graphene oxide − in cementitious composites can effectively enhance their brittle structure, microstructure, strength, and durability performance. For instance, it was reported that the flexural and compressive strengths of reactive powder concrete reinforced with nano SiO 2 -coated TiO 2 improved by 87% MPa and 12.26% MPa compared with the plain sample.…”

Section: Introductionmentioning

confidence: 99%

Dispersion Stability and the Reaction Mechanism of Boron Nitride Nanosheets in a Cementitious Alkaline Environment: An Experimental and Computational Study

Ranjkesh Rashteh Roudi,

Hosseini,

Ranjkesh

et al. 2024

ACS Appl. Nano Mater.

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Boron nitride nanosheets (BNNSs) have attracted the attention of researchers for their extraordinary mechanical properties, large surface areas, and strong interactions with the host matrix, making them ideal candidates as supplementary materials for the construction industry. However, the major challenge associated with the incorporation of BNNSs in cement-based materials is their unfavorable dispersion in a cementitious alkaline environment. In this work, experimental and computational methods were employed to trace the influential factors that hindered the proper dispersion of BNNSs within cementitious composites. The results showed that the BNNS dispersion remained stable in mild alkaline environments with pH values ranging from 7.5 to 12.2, but high alkalinity (pH = 13.1) reduced the BNNS dispersion. Among the various cations, Ca 2+ is the most reactive cation for BNNS agglomeration in a cementitious alkaline environment. To protect BNNS against these influential factors, polycarboxylate ether-based superplasticizer (PCE) was selected as a suitable treatment to improve the dispersion stability of BNNS within cementitious composites. The formation of covalent bonds between calcium silicate hydrate and BNNS resulted in enhanced charge transfer and consequently improved the load transfer from the matrix to the BNNS. Finally, based on the mechanical tests, with the addition of only 0.01 wt % PCE-treated BNNSs, the compressive and flexural strengths of the cement samples improved by 43 and 13%, respectively, which clearly showed the significance of stable BNNS dispersion using PCE on the performance of the final cement composite. The results of this study could improve the fundamental understanding of BNNS-containing cementitious nanocomposites.

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Section: Introductionmentioning

confidence: 99%

Dispersion Stability and the Reaction Mechanism of Boron Nitride Nanosheets in a Cementitious Alkaline Environment: An Experimental and Computational Study

Ranjkesh Rashteh Roudi,

Hosseini,

Ranjkesh

et al. 2024

ACS Appl. Nano Mater.

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“…Despite the benefits of graphene oxide (GO) in cement mortar, an excess of oxygen functional groups in GO would trigger undesirable issues inside cement-based concrete. This is because both the negative charge of GO and the positive charge of Ca 2+ , Na + , and K + existing inside the cement matrix tend to agglomerate due to van der Waals forces [17]. The increased formation of agglomerates may result in the formation of a weak zone within the concrete matrix.…”

Section: Introductionmentioning

confidence: 99%

Assessment of the Mechanical Properties of High Strength Mortar Incorporating Silica Fume and Graphene Nanoplatelets: Experimental and Mathematical Modeling

et al. 2023

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Cement-based mortar is recognized as a popular and cost-effective material for the rehabilitation and repair of reinforced concrete structures. However, the development of high-performance cement-based mortar is in high demand in order to not only enhance compressive strength but also to prolong the mortar lifespan and minimize maintenance costs as much as possible. In the current study, high-strength mortars incorporating both silica fume and graphene nanoplatelets (GNPs) were investigated and evaluated based on compressive and flexural strength. The graphene powder was added in amounts ranging from 0.5% to 2%, by cement weight, while silica fume was added as a partial replacement for cement (10%). The optimal content of the graphene was determined using response surface methodology (RSM). In addition, field emission scanning electron microscopy (FESEM) was used to assess the proposed mortar at the micro-scale level. The outcome revealed that the graphene-based mortar imparted superior mechanical properties compared to the control mixture. The compressive and flexural strength of the mortars containing 10% silica fume and 1% graphene increased by 33% and 35%, respectively. This positive result was attributed to the refinement of the nanopores and tiny cracks by the inclusion of GNPs, which was supported by microstructure testing. The RSM model was also shown to be capable of optimizing and predicting compressive and flexural strength with less error. It is possible to conclude that graphene-based high-strength mortar will serve as a sustainable material in the near future.

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“…Although GO has benefits when mixed with cement, an excess of oxygen functional groups in GO can cause problems in the cement-based matrix. This is because the positive charge of Ca 2+ , Na + , and K + in the cement matrix and the negative charge of GO can cause agglomeration due to van der Waals forces, resulting in the formation of a weak zone within the cement-based matrix [33]. In another study conducted by Kei cui et al [19], which studied the impact of CNTs on the UHPC with two different dosages (0.09%, 0.15%), the results show great strength of the concrete, which contain CNTs with a large aspect ratio of 250-1500.…”

Section: Introductionmentioning

confidence: 99%

Development of Ultra-High-Performance Silica Fume-Based Mortar Incorporating Graphene Nanoplatelets for 3-Dimensional Concrete Printing Application

Salah,

Mutalib,

Kaish

et al. 2023

Buildings

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Although the use of 3D printing in civil engineering has grown in popularity, one of the primary challenges associated with it is the absence of steel bars inside the printed mortar. As a result, developing 3D printing mortar with ultra-high compressive, flexural, and tensile strengths is critical. In the present study, an ultra-high-performance mortar incorporating silica fume (SF) and graphene nanoplatelets (GNPs) was developed for 3D printing application. The concrete mixture added SF to the concrete mixture in the range between 0% and 20%, while GNPs were added as a partial replacement by cement weight from 0.5% to 2%. The flowability and the machinal properties of the proposed mortar, including compressive (CS), tensile (TS), and flexural strength (FS), were investigated and assessed. Microstructure analysis involving FESEM and EDX was also investigated and evaluated, while response surface methodology (RSM) was considered to predict and optimize the optimum value of GNPs and SF. Workability results show that the flowability is reduced when the amount of graphene increases. Based on the predicted and experimental results, ultra-high-strength mortar can be developed by including 1.5% of GNPs and 20% of SF, in which the CS jumped from 70.7 MPa to 133.3 MPa at the age of 28 days. The FS and TS were 20.66 MPa and 14.67 MPa compared to the control mix (9.75 MPa and 6.36 MPa), respectively. This favorable outcome was credited to the pozzolanic activity of SF and the effectiveness of GNPs in compacting the pores and bridging the cracks at the nanoscale level, which were verified by FE-SEM and EDX. In addition, the developed quadratic equations proved their accuracy in predicting and optimizing the mechanical properties with low error (less than 0.09) and high correlation (R2 > 0.97). It can be concluded that the current work is an important step forward in developing a 3D printing mortar. The lack of reinforcement in the printed mortar structure has been a considerable difficulty, and the SF and GNPs have increased the compressive, flexural, and tensile strengths of the mortar. Thus, these improvements will encourage the industry to utilize sustainable materials to produce more affordable housing.

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Evaluation of the dispersion of metakaolin–graphene oxide hybrid in water and cement pore solution: can metakaolin really improve the dispersion of graphene oxide in the calcium-rich environment of hydrating cement matrix?

Abstract: The aggregation mechanism of an MK–GO hybrid in the pH range of 10–11 due to the surface complexation between Al(OH)4− formed by MK dissolution and the graphene layer of GO through Lewis acid–base interaction.

Cited by 16 publications

References 63 publications

Dispersion Stability and the Reaction Mechanism of Boron Nitride Nanosheets in a Cementitious Alkaline Environment: An Experimental and Computational Study

Dispersion Stability and the Reaction Mechanism of Boron Nitride Nanosheets in a Cementitious Alkaline Environment: An Experimental and Computational Study

Assessment of the Mechanical Properties of High Strength Mortar Incorporating Silica Fume and Graphene Nanoplatelets: Experimental and Mathematical Modeling

Development of Ultra-High-Performance Silica Fume-Based Mortar Incorporating Graphene Nanoplatelets for 3-Dimensional Concrete Printing Application

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