High Strength Concrete With Carbon Nanotubes

Hela, Rudolf; Bodnárová, Lenka; Florian, Aleš; Ševelová, Lenka

doi:10.3850/978-981-07-5354-2_m-39-377

Cited by 3 publications

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“…Our previous researches in this area [9,[16][17] were mainly focused on inert carbon nanofibers and nanotubes, the verification of the effect of inorganic nanofibers from silica is a new direction of our research.…”

Section: Discussionmentioning

confidence: 99%

Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

2019

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The paper deals with the verification of the effect of the addition of inorganic SiO2 nanofibers to cement composites. In the first stage, a stable suspension of SiO2 nanofibers was prepared in an aqueous medium. It is important to distribute nanofibers so that the nanofibers do not appear in the form of clumps and at the same time do not get damaged during the dispersion process. The ultrasonification process was used for dispersion. The dispersed suspension of SiO2 nanofibers and water was dosed together with the superplasticizing admixtures into the dry components of the cement composite and the components were homogenized. The properties of the cement composite with SiO2 nanofibers have been tested – compressive strength, flexural strength, density. Composites with the addition of SiO2 nanofibers at a dose of 0.008 % by weight of cement exhibited an increased compressive strength of up to 33 % and a 19 % greater flexural strength at doses of 0.016 and 0.032 % of cement weight than the reference sample without nanofibers. The presence of SiO2 nanofibers in the composite was monitored by scanning electron microscopy (SEM).

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Section: Discussionmentioning

confidence: 99%

Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

2019

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“…Nowadays, cement technology is increasingly using nanoparticles instead of microparticles for HSC, such as carbon nano-tube (CNT), nano-silica, nano-TiO 2 , nano-Fe 2 O 3 , and nano-cement. The increasing rate of production and use of HSC in structures necessitates an accurate assessment of the performance and properties of HSC [2,3,4]. To assess the compressive strength of concrete in a structure, a calibration relation between the rebound number and compressive strength must be available.…”

Section: Introductionmentioning

confidence: 99%

Rebound Hammer Tests of High-Strength Concrete: Effects of Internal Stress and the Shape of the Impact Area of the Test Specimens on the Measurement Results

Bodnárová¹,

Brožovský²

2019

Period. Polytech. Civil Eng.

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This study examines the factors affecting the results of non-destructive testing of high-strength concrete performed on cubes and on cylinders and examines the processing of calibration relations. Tests were performed with both a type N and a type L Schmidt impact hammer (with a standard impact energy of 2.205 Nm and 0.735 Nm respectively). The assessed factors were internal stress in a specimen and the shape of the impact area. Test specimens were loaded by a force corresponding to the stress in specimen 0%, 10%, 20%, 30%, and 50% from the expected compressive strength. Rebound numbers of the unloaded test specimens were significantly lower than those of the loaded specimens. Therefore, calibration relations and/or correction coefficients processed by measurements of unloaded specimens can be assessed as unsuitable. To process calibration relations, we recommend exerting internal stress in amounts of 15% to 20% of the expected compressive strength of the tested HSC samples. During the determination of the effect of the shape of the test area on the cylindrical test specimen, it was assumed that the rebound numbers on the plane and the round test area would be the same. However, the test results revealed that the rebound numbers in the differently shaped test areas were different. For Schmidt impact hammer type N, the rebound numbers in the round test area were lower by 0.7 units on average, and for Schmidt impact hammer type L, the rebound numbers in the round test area were lower by 1.7 units on average compared to the plane test area rebound numbers.

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“…Development of hydration heat in time has considerable effect on resulting properties of concrete. Its properties is important particularly for designing of larger elements, for processes of setting acceleration or for placing fresh concrete under worse thermal conditions [1,2]. Development of hydration heat can be examined by monitoring of temperature during hydration, because if thermal accumulation of test specimen is neglected, direct proportion between temperature of test specimen during hydration and intensity of hydration heat development can be defined.…”

Section: Introductionmentioning

confidence: 99%

Possibilities of Regulation of Temperature in Concrete during Hydration by Means of Selection of Suitable Input Materials

Hela

Zach

Sedlmajer

2014

AMM

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Paper is focused on development of hydration heat in concrete in time. Possible ways of reduction of temperature during concrete hydration are mentioned. Paper presents study of possibilities of regulation temperature in concrete during hydration by selection of suitable input components. Blast furnace slag and micronized limestone were added to pure Portland cement; several variants of proportions were proposed.

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High Strength Concrete With Carbon Nanotubes

Cited by 3 publications

References 0 publications

Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

Rebound Hammer Tests of High-Strength Concrete: Effects of Internal Stress and the Shape of the Impact Area of the Test Specimens on the Measurement Results

Possibilities of Regulation of Temperature in Concrete during Hydration by Means of Selection of Suitable Input Materials

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High Strength Concrete With Carbon Nanotubes

Cited by 3 publications

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Effect of Inorganic SiO2 Nanofibers in High Strength Cementitious Composites

Effect of Inorganic SiO2 Nanofibers in High Strength Cementitious Composites

Rebound Hammer Tests of High-Strength Concrete: Effects of Internal Stress and the Shape of the Impact Area of the Test Specimens on the Measurement Results

Possibilities of Regulation of Temperature in Concrete during Hydration by Means of Selection of Suitable Input Materials

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Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites

Effect of Inorganic SiO₂ Nanofibers in High Strength Cementitious Composites