Search for Ranking Approaches of Expanded Clay Concrete Quality Criteria

Kroviakov, Sergii; Volchuk, V. M.; Zavoloka, M.V.; Kryzhanovskyi, Vitalii

doi:10.4028/www.scientific.net/msf.968.20

Cited by 19 publications

(9 citation statements)

References 7 publications

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“…The formation of phases of the С 4 АН 19 type contributes to the rapid growth of the early strength of cement paste with alkaline-aluminate accelerator Na[Al(OH) 4 ]. This is consistent with the results reported in [8,10], where it is shown that in an aqueous solution NaOH increases the solubility of CaSO 4 and reduces the solubility of Ca(OH) 2 while Al(OH) 4has a delayed reaction with CaSO 4 to form ettringite. This increases the pH of the aqueous solution to about 13.8 due to an increase in the concentration of Na + in the liquid phase of Portland cement paste.…”

Section: Discussion Of Results Of Investigating the Effect Of Layered...supporting

confidence: 93%

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Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Kropyvnytska

Sanytsky

Kaminskyi³

et al. 2022

EEJET

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The use of layered double hydroxides (LDHs) is a new direction in chemistry of cement. The influence of calcium/aluminum double hydroxides (Ca-Al LDHs) and polycarboxylate ethers (PCE) on the strength development of Portland limestone cement has been investigated. It has been shown that Ca-Al LDHs form in cement slurry with the introduction of alkaline aluminate accelerator Na[Al(OH)4]. It was determined that this contributes to a significant increase in the early strength of cement stone. However, this reduces the setting time of hardening, and there is a decrease in strength with age. At an early stage of structuring in cement paste with the addition of Na[Al(OH)4], metastable high-water hydrate phases of Ca-Al LDHs of type C4AH19 ([Ca2Al(OH)6]2(ОН)2·12H2O) are formed, which, due to the conversion phenomenon, transform to cubic C3AH6. Such processes are accompanied by an increase in overall porosity and decreases in the strength of cement stone. Stabilization of the Ca-Al LDH structure is achieved by introducing anions [NO3]- into the interlayer space with the formation of Ca-Al-NO3 LDHs through the use of sol-gel technology. X-ray phase analysis, IR spectroscopy, and electron microscopy proved the fact of synthesis of AFm-phases of type [Ca2Al(OH)6]2(NO3)2.6H2О. When modifying such hydrates with polycarboxylate ethers, a nanocomposite Ca-Al-NO3 LDHs-РСЕ is formed. It was found that when the Ca-Al-NO3 LDHs-РСЕ nanocomposite was introduced to СЕМ ІІ/A-LL 42,5 R, the strength over the period of 8...24 hours increases by 2.0–1.5 times, and, after 2 and 28 days, 58 and 144 % of the standard strength is achieved (Rс28=62.5 MPa). The obtained nanomodified Portland limestone cement refers to extra rapid-hardening and high-strength cement, which makes it possible to solve the task of carrying out work on the rapid restoration of reinforced concrete structures' elements

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Section: Discussion Of Results Of Investigating the Effect Of Layered...supporting

confidence: 93%

“…Therefore, there is an acute issue to restore building structures using special repair mixtures. At the same time, the main criteria are the high speed of repair and restoration work, as well as the durability and operational reliability of buildings and structures [3,4].…”

Section: Introductionmentioning

confidence: 99%

Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Kropyvnytska

Sanytsky

Kaminskyi³

et al. 2022

EEJET

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“…Accordingly, increasing of W/C in this case plays a double role. On the one hand, the content of free water increases, which affects the porosity of hardened concrete, on the other hand, the conditions of hardening of the material and the adhesion of the cement-sand matrix to the aggregate improve [22].…”

Section: Research Resultsmentioning

confidence: 99%

Properties of Concrete and Fiber-Reinforced Concrete for Bases of Road Clothes Based on Secondary Aggregates With Heterogeneous Composition

Kroviakov,

Chystiakov

2024

Modern Construction and Architecture

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The problem of disposal of concrete scrap of dismantled building structures is relevant for most countries of the world. For Ukraine, this problem is even more acute due to the significant amount of destruction caused by hostilities and rocket attacks. In current research the properties of concrete and fibre-reinforced concrete for the bases of road clothes based on natural and secondary aggregates were compared: granite river gravel, secondary crushed stone with a heterogeneous composition, quartz sand and secondary sand from recycled reinforced concrete structures. CEM III/A slag Portland cement with a blast furnace slag content of 65% and a polycarboxylate type superplasticizer were used. Three series of samples were studied: without fibre; with glass fibre ANTI-CRAK HP 12 (length 12 mm, diameter 0.017 mm, equivalent thread diameter 0.3 mm) in the amount of 1 kg/m3; with polypropylene fibre BeneSteel 55 (length 55 mm, equivalent thread diameter 0.48 mm) in the amount of 4 kg/m3. In each series, concrete on granite gravel and quartz sand, concrete on secondary crushed stone and quartz sand, concrete on secondary crushed stone and secondary sand were studied. The workability of all mixtures was equal to S1. Due to the use of different types of aggregates and fibres, the W/C of concrete mixtures differed significantly. Concretes on secondary aggregates had a higher W/C than on natural aggregates. When using the Anti-Crak HP 12 fibre, the mobility of mixtures with equal W/C increased by 5.5 – 6.9 %. When using BeneSteel 55 fibre, W/C increased by 10.6 – 15.5 %. The type of aggregate had a significant effect on the average density of concrete. When using secondary crushed stone and quartz sand, the average density decreased by 3.8 – 4.6 %. When using secondary crushed stone simultaneously with secondary sand, the average density of concrete decreased by 5.2 – 8.5 %. When using Anti-Crak HP 12 fiber, the average density of concrete decreases by 2 %, when using BeneSteel 55 fibre – up to 4.1 %. Concretes on secondary crushed stone with heterogeneous composition and quartz sand had 4 % higher compressive strength and 2 % higher tensile strength in bending than concretes on granite gravel and similar sand (29.8 MPa and 3.18 MPa, respectively). When secondary crushed stone is used simultaneously with secondary sand, the compressive strength of concrete is only 1.1 % lower than the strength of concrete on natural aggregates, and the tensile strength in bending is 10 % lower. This confirms the possibility of effective use of these concretes for arranging of bases of road clothes. The high-quality performance of secondary aggregates in concrete explains due to their better adhesion to the cement-sand matrix. Dispersed fibre reinforcement with Anti-Crak HP 12 has a positive effect on the compressive strength of concrete on all types of aggregate and increases the tensile strength of concrete on natural aggregates. The use of BeneSteel 55 fibre was not effective due to a significant increase in the W/C of the mixture when it was introduced. In general, taking into account the economic factor, dispersion reinforcement of concrete on secondary aggregates with the types of fibres used in the research is not advisable.

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“…фрактального аналізу [22][23][24][25]; мультифрактального аналізу [26][27][28] [35; 36]. Коефіцієнти парної кореляції в рівняннях прогнозу показників твердості робочої зони бочок листопрокатних валків становлять для аустенітної матриці R 2 = 0,71 та R 2 = 0,85, для карбідів хрому  R 2 = 0,95 і R 2 = 0,89.…”

Section: актуальність роботиunclassified

Model of assessment of the hardness of the iron rollers СПХН-43 and СШХНФ-47

Volchuk

2019

PM&HTM

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Search for Ranking Approaches of Expanded Clay Concrete Quality Criteria

Cited by 19 publications

References 7 publications

Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Effect of layered double hydroxides Ca-Al LDHs and polycarboxylate ethers on the hardening of Portland limestone cement

Properties of Concrete and Fiber-Reinforced Concrete for Bases of Road Clothes Based on Secondary Aggregates With Heterogeneous Composition

Model of assessment of the hardness of the iron rollers СПХН-43 and СШХНФ-47

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