Modification of concrete by hydrothermal nanosilica

Потапов, В. В.; Efimenko, Yu.V.; Gorev, D.S.

doi:10.15828/2075-8545-2019-11-3-248-265

Cited by 8 publications

(9 citation statements)

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“…Furthermore, a decrement in the time required to reach the maximum rate was observed. It has been reported that silica nanoparticles, due to their ultrafine size, act as a nucleus for cement hydration, which results in faster formation of CH and more dynamic consumption of tricalcium silicate phase (C 3 S) during the binding period; in turn, this results in an accelerated cement hydration process (Xu et al 2016;Flores et al 2017;Kotsay 2017;Potapov et al 2019). As a result, the combination of seawater with NS resulted in a substantial acceleration of the hydration process.…”

Section: Resultsmentioning

confidence: 99%

The effects of seawater and nanosilica on the performance of blended cements and composites

Sikora

Lootens²,

Liard³

et al. 2020

Appl Nanosci

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This study investigates the effects of seawater and nanosilica (3% by weight of cement), on the fresh and hardened properties of cement pastes and mortars produced with two types of low heat cements: Portland pozzolana cement (CEM II) and blast furnace cement (CEM III). The heat of hydration, initial and final setting times, rheological properties, strength development, sorptivity and water accessible porosity of the cement pastes and mortars were determined. The data reveal that cement type has a significant effect on the reaction rate of cement with seawater and nanosilica (NS). Specimens produced with slag-blended cement exhibited a higher cement reaction rate and the composite produced exhibited better mechanical performance, as a result of the additional reaction of alumina rich phases in slag, with seawater. Replacement of freshwater with seawater contributes mostly to a significant improvement of early strength. However, in the case of slag-blended cement, 28 day strength also improved. The incorporation of NS results in additional acceleration of hydration processes, as well as to a decrease in cement setting time. In contrast, the addition of NS results in a noticeable increment in the yield-stress of pastes, with this effect being pronounced when NS is mixed along with seawater. Moreover, the use of seawater and NS has a beneficial effect on microstructure refinement, thus improving the transport properties of cement mortars. Overall, the study has showed that both seawater and NS can be successfully used to accelerate the hydration process of low heat blended cements and to improve the mechanical and transport properties of cement-based composites.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

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Section: Resultsmentioning

confidence: 99%

The effects of seawater and nanosilica on the performance of blended cements and composites

Sikora

Lootens²,

Liard³

et al. 2020

Appl Nanosci

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“…-studies of the possibility of using nanopowders as catalyst supports. Using SiO 2 nanoparticles, which have a high and chemically active surface, one can purposefully influence [68][69][70][71][72][73][74][75][76][77][78][79]:…”

Section: Prospects For Research and Applications Of Hydrothermal Nanomentioning

confidence: 99%

“…-the kinetics of hydration of the basic cement minerals C 3 S, C 2 S, C 3 A, C 4 AF and increasing the rate of CSH gel formation up to 20% and polymerisation [68,69,77,78];…”

Section: Prospects For Research and Applications Of Hydrothermal Nanomentioning

confidence: 99%

“…-reducing content of Ca(OH) 2 up to 20% to 30% and, thus, increasing content of CSH gel in hardened concrete because of rapid kinetics of pozzolanic reaction of SiO 2 nanoparticles with Ca(OH) 2 [74,75]; hydrothermal SiO 2 nanoparticles with great specific surface area up to 500 m 2 /g and high chemical activity due the surface density of Si-OH groups up to 4.9 nm −2 , which significantly accelerates the kinetics of pozzolanic reaction [68,77,78]; -increase the volume fraction of C-S-H gel phases with greater elasticity and hardness, Ca/Si relation due to modification of nanostructure of hardened concrete, and, as a result, increase the compressive and bending strength of concrete, reduce pore volume, increase water resistance, frost resistance, chemical resistance, and, as a result, the durability of concrete.…”

Section: Prospects For Research and Applications Of Hydrothermal Nanomentioning

confidence: 99%

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Hydrothermal SiO2 Nanopowders: Obtaining Them and Their Characteristics

2020

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The technological mode of obtaining amorphous SiO2 nanopowders based on hydrothermal solutions is proposed in this study. Polycondensation of orthosilicic acid as well as ultrafiltration membrane separation, and cryochemical vacuum sublimation were used. The characteristics of nanopowders were determined by tunneling electron microscopy, low-temperature nitrogen adsorption, X-ray diffraction, and small-angle X-ray scattering. The scheme allows to adjust density, particle diameters of nanopowders, specific surface area, as well as diameters, area and volume of the pore. Thus, the structure of nanopowders is regulated—the volume fraction of the packing of spherical particles in aggregates and agglomerates, the size of agglomerates, and the number of particles in agglomerates. The pour densities of the nanopowders depend on the SiO2 content in sols, which were 0.02 to 0.3 g/cm3. Nanoparticles specific surface area was brought to 500 m2/g by low temperature polycondensation. Nanoparticle aggregates specific pore volume (0.2–0.3 g/cm3) weakly depend on powders density. The volume fraction of the packing of SiO2 nanoparticles in aggregates was 0.6–0.7. Solid samples of compacted nanopowders had a compressive strength of up to 337 MPa. Possible applications of hydrothermal SiO2 nanopowders are considered.

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“…Due to its much smaller size in relation to cement grains, nanoparticles are the "filler" created in the process of the hydration of voids. Nanosilica fills the pores between the calciumsilicate-hydrate (C-S-H) gel particles, thickens microstructure and thus improves the mechanical properties of the structure formed [9,10]. Silica nanoparticles also exhibit pozzolanic properties; after the incorporation of pozzolanic material in concrete or mortar, the total calcium hydroxide (CH) content decreases, with additional amounts of hydrated calcium silicates being formed in its place.…”

Section: Introductionmentioning

confidence: 99%

The effects of low curing temperature on the properties of cement mortars containing nanosilica

Skoczylas¹,

Rucińska²

2019

Nanobuild

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This study presents the experimental results on the effects of curing temperature and nanosilica, on the compressive strength and absorbing properties of cement mortars. Two groups of mortars were prepared, with the first containing reference samples. The second group was modified with a nanosilica admixture by 3% of the weight of cement. The mortar specimens were cured in 20 о C, 10 о C and 5 о C constant temperature environments. Compressive strength after 12 h, 1, 2, 7 and 28 days, water absorption and capillary porosity were evaluated on a 40×40×40 mm prism. The results confirmed that a low curing temperature delays strength development in the early days of hydration and slows down the strength growth rate of mortars, with an increase in age. The incorporation of nanosilica has a positive effect in improving the mechanical properties of cement mortars cured at low temperatures. Additionally, nanosilica contributes to decreasing the porosity of the cement matrix, so that transport properties, such as open porosity and sorptivity, improve under all curing conditions.

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Modification of concrete by hydrothermal nanosilica

Cited by 8 publications

References 0 publications

The effects of seawater and nanosilica on the performance of blended cements and composites

The effects of seawater and nanosilica on the performance of blended cements and composites

Hydrothermal SiO2 Nanopowders: Obtaining Them and Their Characteristics

The effects of low curing temperature on the properties of cement mortars containing nanosilica

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