Modelling mechanical behavior of cementitious material incorporating CNTs using design of experiments

Hassan, Noha M.; Fattah, Kazi Parvez; Al-Tamimi, Adil K.

doi:10.1016/j.conbuildmat.2017.07.218

Cited by 38 publications

(23 citation statements)

References 20 publications

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“…The concentrations of CNTs ranged from 0.007 c-wt% [92] to 2 c-wt% [94]. The mechanical properties improve as κ increases up to a certain limit, beyond which the mechanical properties degrade due to the dispersion issues [28,31,110,174,189]. Also, the optimum κ is correlated with CNT aspect ratio (AR).…”

Section: Other Important Variables and Their Interactionsmentioning

confidence: 99%

“…Conversely, in case of κ = 0.3 c-wt%, the relative exhibited a significant increase from 0.96 to 1.11 in a period of 1 to 28 days (p-value = 0.0381 < 0.05). This might be explained by the lower rate of cement hydration at early ages when using high CNT concentrations[31,116,174]. Summary: Mechanical PropertiesCNTs have the potential to increase the mechanical properties of cementitious materials significantly.…”

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confidence: 99%

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Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

Ramezani¹

2020

Preprint

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Recently, Carbon Nanotubes (CNTs) are drawing considerable attention of researchers for reinforcing cementitious materials due to their excellent mechanical properties and high aspect ratio (length-to-diameter ratio). However, CNTs might not disperse well within the cement matrix, resulting in little improvement or even degradation of concrete properties. The uncertainty in producing the consistent results in different studies might be attributed to multiple interactions between the experimental variables affecting the nanotube dispersion and the final properties of CNT-cement nanocomposites. Therefore, this research mainly focused on proposing equations that can reliably capture these interactions in order to correlate CNT dispersion with the mechanical properties. The main experimental variables studied included CNT concentration, aspect ratio, ultrasonication energy, ultrasonication amplitude, surfactant-to-CNTs ratio, water-to-cement ratio, sand-to-cement ratio, and hydration age of specimen. The study reported in this research was conducted in two parts: experimental program and modeling. In the experimental part of this research, a total of 63 different mix proportions were used to evaluate the flowability, mechanical properties, and durability characteristics of cement pastes and mortars containing CNTs. Using experimental test results reported in this study and the literature, three critical relations were proposed to consider the CNT dispersion, cement matrix composition, and hydration age of cement. The proposed critical relations were then added to available theoretical models in the literature. The flexural strength and elastic modulus of CNT-cement nanocomposites were predicted through a state-of-the-art probabilistic model using a Bayesian methodology. Finally, the developed probabilistic models were used to identify the optimum ranges of the experimental variables to maximize the mechanical properties. This was done through computing the conditional probability of not meeting the specified design requirement. The experimental results indicated that addition of CNTs could significantly improve different properties of cementitious materials, if the optimum range of each variable was used. Also, to achieve the desired mechanical properties, various combinations of the experimental variables might be used. The proposed prediction models were shown to capture the interactions between the experimental variables for predicting the mechanical properties within ±15% and ±18% of the experimental test results for flexural strength and elastic modulus, respectively. Based on the findings of this research, contour plots were developed to provide practical guidelines for future engineers to design CNT-cement nanocomposites.

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Section: Other Important Variables and Their Interactionsmentioning

confidence: 99%

mentioning

confidence: 99%

Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

Ramezani¹

2020

Preprint

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“…Functional groups of CNTs (carboxyl -COOH and hydroxyl -OH) have also been found to affect the physical properties of the cement [4]. It is inferred from the experimental data that the hydrophilic carboxyl CNTs might initiate a chemical reaction between the carboxyl groups and the composites present in the cement.…”

Section: Introductionmentioning

confidence: 99%

“…In general it is perceived that the nanomaterials occupy the pores in the hydrated cement paste and therefore act as binders between the grains [3,4]. There are, however, studies to suggest that the nanoparticles (particularly 3d metals) might occupy interstitial positions in the crystal structure of clinker [5,6] and thus accelerate the hydration process.…”

Section: Introductionmentioning

confidence: 99%

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Role of electrostatic potential energy in carbon nanotube augmented cement paste matrix

Azeem

Saleem

2020

Construction and Building Materials

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The empirical data in conjunction with the quantum mechanical calculations show that the strength enhancement in the cement-carbon nanotubes (CNTs) composites is the courtesy of electrostatic potential energy. This is contrary to the general belief that the CNTs form bridges between the adjacent grains to slow down the breaking process. The yield point for the cement paste is improved up to 25% when prepared with 0.2 % by weight of various types of CNTs. A significant strength enhancement is observed with carboxyl functionalized (COOH) CNTs compared to other types. Further, an increase in the concentration of CNTs up to 0.4 wt% has a negative effect on the strength of the matrix. The electrostatic potential energy is mapped by using density functional theory (DFT) with ωB97X-D functional. At lower concentration of CNTs, ion-dipole interaction in the cement paste and the CNTs creates a very strong long range intermolecular force. Due to the increased entropy resulting from the exothermic hydration process, these forces augment the strength of the cement paste.

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A comprehensive probabilistic prediction and Monte-Carlo simulation of the flexural strength of hybrid graphene oxide/carbon nanotube cementitious nanocomposite

Mahmoodi,

Khamehchi,

Safi

2023

Acta Mech

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Modelling mechanical behavior of cementitious material incorporating CNTs using design of experiments

Cited by 38 publications

References 20 publications

Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

Design and predicting performance of carbon nanotube reinforced cementitious materials : mechanical properties and dispersion characteristics.

Role of electrostatic potential energy in carbon nanotube augmented cement paste matrix

A comprehensive probabilistic prediction and Monte-Carlo simulation of the flexural strength of hybrid graphene oxide/carbon nanotube cementitious nanocomposite

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