Repair Mortars Incorporating Multiwalled Carbon Nanotubes: Shrinkage and Sodium Sulfate Attack

Souza, Diego Jesus de; Yamashita, Luana Y.; Dranka, Francielle; Medeiros, Marcelo Henrique Farias de; Medeiros-Junior, Ronaldo A.

doi:10.1061/(asce)mt.1943-5533.0002105

Cited by 34 publications

(16 citation statements)

References 26 publications

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“…This agrees with what was exposed by Chinchon-Paya et al [8], Araújo [9], Hoppe Filho et al [29], Medeiros et al [30] and Souza et al [31], since the formation of products from the reaction between the hydrate and sulphate ions available, in the voids, fills the spaces and can promote strength gains at an early stage (up to 200 days).…”

Section: Testing Proceduressupporting

confidence: 81%

Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

et al. 2017

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This study aims to investigate cementitious compound behaviour at early stages (up to 168 days), primarily when dosed with different levels of pyrite. To accomplish this, a study was conducted with cement pastes and mortars contaminated by sulphide. For the cement pastes, four contaminant levels were adopted: with one as a reference value (0%), two as cited by the standards, and one value greater than the set standards. In the mortars, two series were studied, one without contamination and the other with use of an aggregate contaminated naturally by pyrite. Pozzolanic cement was used (65% Portland cement CPV ? 35% fly ash) and the materials were submerged in curing compounds for 28 days.Subsequently, the samples were subjected to two exposure conditions: 1-a wet-dry cycle and 2-immersion in aqueous solution with aeration. To identify the products formed by pyrite oxidation, and the subsequent by-product-based reactions, and cement hydrates, scanning electron microscopy with elemental analysis was used. For the analysis of the mechanical properties, strength tests were performed to test axial compression and tensile strength in bending. Furthermore, monitoring of the dimensional variation in prisms (2.5 9 2.5 9 28.5) cm 3 was performed. In conclusion, we determined that at the exposure times tested, there were signs of sulphide oxidation in the contaminated compounds. It was proven that the higher the degree of pyrite contamination, the higher the relative expansion of the series, which was confirmed by the formation of expansive products identified in the scanning electron microscopy.

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Section: Testing Proceduressupporting

confidence: 81%

Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

et al. 2017

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“…This loading rate is also in line with that suggested by B. Han et al The loading rate of sensing cementitious material has been obtained from the works of B. Han et al [68]. [62] For each mix, an average of 3 cubes were tested in Saturated Surface Dry (SSD) conditions. The maximum load (in KNkN) was recorded for each sample, average was calculated for each mix composition, and used for comparative analysis.…”

Section: Testing Proceduressupporting

confidence: 79%

Use of silica particles to improve dispersion of -COOH CNTs/carbon fibers to produce HyFRCC

Garg

Das

Gupta

2020

Construction and Building Materials

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The development of hybrid fiber reinforced cement composite that has high strength, scope to be used as cement-based sensors has been investigated in this study by using a combination of carbon fibers and carbon nanotubes (CNT) at low volume fraction. The dispersion of CNTs was enhanced by using polycarboxylate based superplasticizer that resulted in a homogeneous aqueous stable solution, and profoundly improved dispersion when integrated with the cementitious matrix. Different siliceous additives were also incorporated into the mixes to improve the dispersion of CNTs in the matrix, where micro-silica outperformed as compared to nano-silica, confirmed morphologically. On the other hand, nano-silica enhanced dispersion of milled carbon fibers in the aqueous state. The sensing behavior was determined by the measurement of bulk resistance of mixes and the samples were subjected to compressive loading to study the strength improvement with the incorporation of fibers. The experimental results reveal that hybrid combination of chopped carbon fibers, micro silica, and low volume fraction of CNTs in a cementitious matrix results in a stronger and durable concrete that holds the potential for sensing applications. Thus, laying a strong foundation for the future of low cost smart cement based materials.

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“…F. Blandine et al [65] demonstrated the effect of CNTs on the reduction of the autogenous shrinkage of cement paste attributed to the combined effect of nano-reinforcing properties, hydration alterations and the microstructure of the hydrated matrix. A study on shrinkage and sodium sulfate attack on repair mortars containing MWCNTs was conducted [66]. In contrast to many studies, both test results showed a negative impact on the incorporation of MWNCTs.…”

Section: Durability Properties Of Cementitious Composites Incorporatimentioning

confidence: 97%

The Effect of Carbon Nanotubes on the Flowability, Mechanical, Microstructural and Durability Properties of Cementitious Composite: An Overview

2020

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Excellent mechanical properties and chemical stability make carbon nanotubes (CNTs) some of the most promising nanomaterials that can be used in cementitious composites to improve their performance. However, the difficulty of CNTs’ dispersion within the cementitious structure still exists and thus prevents the homogeneous distribution of CNTs. The homogeneous distribution of CNTs within a composite structure plays an essential role that can have a positive effect on the mechanical performance of CNT-cement composites. This paper introduces the methods for the production of CNTs and provides useful information about the influence of CNTs on the flowability, mechanical performance, microstructural changes and hydration of cement composites. The influences of water-cement ratio, used surfactants and various doses of CNTs on the properties of cementitious composites were also studied.

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Repair Mortars Incorporating Multiwalled Carbon Nanotubes: Shrinkage and Sodium Sulfate Attack

Cited by 34 publications

References 26 publications

Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

Internal attack by sulphates in cement pastes and mortars dosed with different levels of pyrite

Use of silica particles to improve dispersion of -COOH CNTs/carbon fibers to produce HyFRCC

The Effect of Carbon Nanotubes on the Flowability, Mechanical, Microstructural and Durability Properties of Cementitious Composite: An Overview

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