Residual mechanical properties of mortars containing carbon nanomaterials exposed to high temperatures

Nalon, Gustavo Henrique; Ribeiro, José Carlos Lopes; Araújo, Eduardo Nery Duarte de; Pedroti, Leonardo Gonçalves; Carvalho, José Maria Franco de; Santos, Rodrigo Felipe; Oliveira, Diego Sales de

doi:10.1016/j.conbuildmat.2020.122123

Cited by 17 publications

(8 citation statements)

References 70 publications

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“…This result is important, as some organic compounds can strongly influence hydration reactions and, in some cases, even inhibit them [145]. The weight loss for the CB is presented in Figure 5, where the powder is stable until reaching 600 • C, after which it starts oxidating, forming carbon oxides [146]. Its decomposition was continuous up to 765 • C, similar to what was found by Nalon et al [86,146].…”

Section: Carbon Black Characterisation Thermogravimetric Analysissupporting

confidence: 71%

Strain Monitoring of Concrete Using Carbon Black-Based Smart Coatings

Milone,

Vlachakis,

Tulliani

et al. 2024

Materials

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Given the challenges we face of an ageing infrastructure and insufficient maintenance, there is a critical shift towards preventive and predictive maintenance in construction. Self-sensing cement-based materials have drawn interest in this sector due to their high monitoring performance and durability compared to electronic sensors. While bulk applications have been well-discussed within this field, several challenges exist in their implementation for practical applications, such as poor workability and high manufacturing costs at larger volumes. This paper discusses the development of smart carbon-based cementitious coatings for strain monitoring of concrete substrates under flexural loading. This work presents a physical, electrical, and electromechanical investigation of sensing coatings with varying carbon black (CB) concentrations along with the geometric optimisation of the sensor design. The optimal strain-sensing performance, 55.5 ± 2.7, was obtained for coatings with 2 wt% of conductive filler, 3 mm thickness, and a gauge length of 60 mm. The results demonstrate the potential of applying smart coatings with carbon black addition for concrete strain monitoring.

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Section: Carbon Black Characterisation Thermogravimetric Analysissupporting

confidence: 71%

Strain Monitoring of Concrete Using Carbon Black-Based Smart Coatings

Milone,

Vlachakis,

Tulliani

et al. 2024

Materials

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“…Temperature is an important factor leading to the deterioration of concrete, as high temperatures will bring high-temperature vapor pressure, thermal stress and thermal decomposition of the hydration products and other adverse factors [2][3][4][5][6][7], and eventually lead to the deterioration of the appearance of concrete (cracking, spalling or even explosion) and compressive strength loss.…”

Section: Discussion Of Resultsmentioning

confidence: 99%

“…The reasons for concrete degradation at high temperature are as follows: high temperature vapor pressure, temperature stress, difference in thermal expansion coefficient between aggregate and paste and thermal decomposition of hydration products [2][3][4][5][6][7], among which the main reasons for concrete degradation are high temperature vapor pressure and thermal decomposition of hydration products. Under 400 • C, the hydration products of concrete do not obviously decompose, the deterioration of concrete is mainly due to the high temperature vapor pressure; when the temperature exceeds 400 • C, the calcium hydroxide (CH), C-S-H gel and calcium carbonate (CaCO 3 ) of concrete decompose, resulting in a decline of concrete strength [8][9][10].…”

Section: Introductionmentioning

confidence: 99%

High Temperature Degradation Mechanism of Concrete with Plastering Layer

Liu

Chen

2022

Materials

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At present, the research on the high temperature degradation of concrete usually focuses on only the degradation of concrete itself without considering the effect of the plastering layer. It is necessary to take into account the influence of the plastering layer on the high temperature degradation of concrete. With an increase in the water/cement ratio, the explosion of concrete disappeared. Although increasing the water/cement ratio can alleviate the cracking of concrete due to lower pressure, it leads to a decrease in the mechanical properties of concrete after heating. It is proved that besides the water/cement ratio, the apparent phenomena and mechanical properties of concrete at high temperature can be affected by the plastering layer. The plastering layer can relieve the high temperature cracking of concrete, and even inhibit the high temperature explosion of concrete with 0.30 water/cement ratio. By means of an XRD test, scanning electron microscope test and thermogravimetric analysis, it is found that the plastering layer can promote the rehydration of unhydrated cement particles of 0.30 water/cement ratio concrete at high temperature and then promote the mechanical properties of concrete at 400 °C. However, the plastering layer accelerated the thermal decomposition of C-S-H gel of concrete with a water/cement ratio of 0.40 at high temperature, and finally accelerate the decline of mechanical property of concrete. To conclude, the low water/cement ratio and plastering layer can delay the deterioration of concrete at high temperature.

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“…The mix proportions (in mass) of each composition are indicated in Table 1. To obtain mortar mixtures with suitable workability and ensure good compaction, previous research 5,26 recommended to increase the SP dosage with the increase in CBN content. Therefore, in order to always achieve a minimum flow index of 220 mm (diameter of spread of the fresh mixture in a flow table test, according to prescriptions of ABNT NBR 13276 27 ), the mortars of the present study were produced with concentrations between 0% and 2.75% (by weight of cement) of a polycarboxylate SP solution (MC-Powerflow 4001) provided by the manufacturer for use as received.…”

Section: Methodsmentioning

confidence: 99%

Microstructural Investigation of the Effects of Carbon Black Nanoparticles on Hydration Mechanisms, Mechanical and Piezoresistive Properties of Cement Mortars

et al. 2021

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Carbon-black nanoparticles (CBN) have been incorporated into cement-based materials for improvement of mechanical or self-sensing properties. There is no previous research focused on the microstructural evaluation of effects of CBN on both parameters. In this work, mortars containing different CBN contents were produced, cured for 28 days, and subjected to electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopy. Tests for determination of compressive strength, modulus of elasticity and piezoresistivity response were developed. SEM indicated that lower CBN contents refined the cementitious matrix, while higher contents increased the volume of voids. XRD and Raman spectroscopy indicated hydration improvements for CBN contents between 0.375% and 3%. The best mechanical improvements were provided by concentrations of CBN up to 3%. CBN contents of 5% and 6% provided the best sensing properties. The optimal concentration was found to be 5% of CBN, since it provided excellent piezoresistivity, without significant mechanical properties loss.

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Residual mechanical properties of mortars containing carbon nanomaterials exposed to high temperatures

Cited by 17 publications

References 70 publications

Strain Monitoring of Concrete Using Carbon Black-Based Smart Coatings

Strain Monitoring of Concrete Using Carbon Black-Based Smart Coatings

High Temperature Degradation Mechanism of Concrete with Plastering Layer

Microstructural Investigation of the Effects of Carbon Black Nanoparticles on Hydration Mechanisms, Mechanical and Piezoresistive Properties of Cement Mortars

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