Mechanical activation effect on the biostability of modified cement compositions

Stroganov, V. F.; Sagadeev, E. V.; Ibragimov, Ruslan; Potapova, L.I.

doi:10.1016/j.conbuildmat.2020.118506

Cited by 30 publications

(10 citation statements)

References 39 publications

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“…Carbonatation has two effects: it increases mechanical strength of concrete, but it also decreases alkalinity, which creates favorable conditions for fungi growth leading to the loss of calcium in concrete (Figure 5). The 15 fungal isolates identified in this study produced oxalic acid (Figure 2(a)) and therefore form calcium oxalate which creates a protective layer on the concrete surface contributing to positive impact of this acid production [14, 24]. A lower number of isolates producing lactic and malic acids which form more or less soluble calcium salts indicates their prevalent role in pH decrease which promotes the future development of fungi.…”

Section: Discussionmentioning

confidence: 94%

“…Malic acid was found in cultural fluid of 14 micromycetes, acetic acid was synthesized by 10 isolates, citric—by 9, lactic—by 5, and tartaric acid—by two isolates (Figure 2(a)). Oxalic acid, when contacted with the concrete surface, forms a complex of calcium oxalate which has a low solubility and therefore contributes to the formation of a protective layer on the concrete surface which promotes the preservation and strengthening of concrete structure, as well as diminishing of microcracks formation [14]. Nonsoluble calcium tartrate could have the same consequences.…”

Section: Resultsmentioning

confidence: 99%

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Metabolic Activity of Micromycetes Affecting Urban Concrete Constructions

Yakovleva

Sagadeev

Stroganov

et al. 2018

The Scientific World Journal

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Concrete resistance to the destructive action of microorganisms is considered as a measure of its durability and is increasingly being raised as an important issue. We focused our study on the biodeterioration of concrete specimens widely used as a building material of urban houses by micromycetes isolated from the inner wall surface of the former military hospital in Kazan city, Tatarstan, Russia. Fungal community consists of 9 Penicillium isolates, 6 Aspergillus, 2 Trichoderma, and 1 isolate of Alternaria. First, we have identified two dominant isolates, Aspergillus fumigatus and Penicillium brevicompactum, and characterized their destructive properties according to the radial growth rate, antagonistic activity towards bacterial habitants of concrete, and production of organic acids. Then, we have demonstrated that five tested brands of high-strength concrete differ in bioreceptivity. The alterations in concrete resistances to compression and flexure after fungal attack were recorded at the trend level, mainly due to a short exposure time of concrete to fungal destructors in tests recommended by national Russian standard. Finally, using scanning electron microscopy we have shown that colonization of concrete by the dominant fungi includes their penetration into the thickness of concrete and germination in cracks. Elementary analysis revealed the decrease of calcium content on about 41% after fungal growth on the concrete in liquid phase and on 32% by superficial growth in comparison with the samples without fungal treatment.

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Section: Discussionmentioning

confidence: 94%

Section: Resultsmentioning

confidence: 99%

Metabolic Activity of Micromycetes Affecting Urban Concrete Constructions

Yakovleva

Sagadeev

Stroganov

et al. 2018

The Scientific World Journal

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“…In Japan, mini excavators are classified according to bucket volume [17][18][19][20][21][22][23]. Some excavator models are summarized in table.…”

Section: Resultsmentioning

confidence: 99%

Determination of the time norms for excavating soil with a mini excavator

Galiev

Ibragimov

2021

E3S Web Conf.

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Since 2010, there has been a growing trend in the market for mini-excavators from various manufacturers. The range of manufactured equipment is increasing, as well as the technological capabilities of construction equipment are growing. At the same time, in the modern standards of Russia are no figures on the complexity of soil excavation with this type of technology. The article shows the timing of soil excavation using the example of a mini-excavator with a bucket volume of 0.03-0.04 m3. The object of the study is the amount of time the mini-excavator works on II group of soils. The timekeeping method is used to determine the operating time of a mini-excavator with a bucket volume of 0.03 and 0.04 m3. It is experimentally obtained that the norm of time for operation of a mini-excavator with a bucket volume of 0.03m3 is 5.82 mach *hours, and for a bucket volume of 0.04 m3 is 5.37 mach*hour.

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“…The main methods for dispersing CNT are mechanical dispersion (e.g., high-speed ball milling) [13][14][15][16], ultrasonic dispersion [17][18][19][20], electric field induction [21][22][23], surface modification (also called functionalization) [1,24,25], or a combination of these methods. Among the functionalization methods, the most common is by exposing the CNT to a highly acidic environment (e.g., solution of sulfuric and nitric acid) [26][27][28]. In this condition, oxygen atoms from the acid can react with the carbon atoms of the defect sites and/or ends of CNT.…”

Section: Introductionmentioning

confidence: 99%

Combined Functionalization of Carbon Nanotubes (CNT) Fibers with H2SO4/HNO3 and Ca(OH)2 for Addition in Cementitious Matrix

Batiston

Matos

Gleize

et al. 2021

Fibers

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Acid treatment is commonly used to improve the dispersion of carbon nanotubes (CNT) in a cementitious matrix, but it causes undesired delay on cement hydration kinetics. This work reports a combined CNT functionalization method with H2SO4/HNO3 and Ca(OH)2 for addition in a cementitious matrix. Results showed that the Ca(OH)2 exposure neutralized the active sites generated by acid exposure, compensating the delay in hydration. As a result, CNT exposed to H2SO4/HNO3 for 9 h and further Ca(OH)2 treatment led to equivalent hydration kinetics than un-treated CNT did with improved stability.

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Mechanical activation effect on the biostability of modified cement compositions

Cited by 30 publications

References 39 publications

Metabolic Activity of Micromycetes Affecting Urban Concrete Constructions

Metabolic Activity of Micromycetes Affecting Urban Concrete Constructions

Determination of the time norms for excavating soil with a mini excavator

Combined Functionalization of Carbon Nanotubes (CNT) Fibers with H2SO4/HNO3 and Ca(OH)2 for Addition in Cementitious Matrix

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