Influence of nano-silica agglomeration on fresh properties of cement pastes

Kong, Deyu; Su, Yong; Du, Xiangfei; Yang, Yang; Su, Wei; Shah, Surendra P.

doi:10.1016/j.conbuildmat.2013.02.066

Cited by 176 publications

(54 citation statements)

References 19 publications

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“…Agglomeration is expected to influence the rheological properties of pastes and their density, and induce weak zones in compression. However, hydration can be enhanced (Kong et al, 2013). Some mortar cubes were prepared and tested in compression, as shown in the last section of the results, confirming this hypothesis of bad dispersion of low GnS contents in cement pastes.…”

Section: Spectrumsupporting

confidence: 54%

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

Paine

2018

Advances in Cement Research

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2The effect of polycarboxylate/nanosilica (nS) particles in quaternary cement formulations comprising Portland cement (PC), limestone powder (LS) and fly ash (FA) was investigated for the first time. The reference formulation contained 60% PC, 20% LS and 20% FA by mass of binder in an effort to minimise clinker and maximise the other constituents. nS particles were characterised by way of transmission and X-ray scanning electron microscopy (SEM). The nS was added at 0·3 or 0·6% by mass as a partial replacement for PC and different water-to-binder (w/b) ratios were explored. Compressive strength tests and thermal gravimetric analyses (TGA) performed at day 7, 28 and 56 testified to pozzolanic behaviour. Results suggest a mechanism of 'de-activation' of some FA particles with age. A new ratio: (compressive strength in MPa)/(calcium hydroxide content detected by TGA) was introduced, correlating microscale characteristics (hydration products) and macroscale performance (delivered compressive strengths). Back-scattered SEM images confirmed the calcium-silicate-hydrate (C-S-H) network formation, the presence of reacted/unreacted FA particles and the availability of calcium hydroxide for delayed hydration reactions. Tests on mortars also confirmed the enhancement offered by nS addition. The lower bound nS addition was determined to be 0·6% by mass of binder for pastes and 0·5% for mortars.Notation D relative density m a mass of specimen in air m w apparent mass of specimen immersed in water w/b water-to-binder ratio ρ w density of water

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Section: Spectrumsupporting

confidence: 54%

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

Paine

2018

Advances in Cement Research

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“…), a nano-silica with a specific surface area of 50 m /g cannot perform as a nano-silica with a specific surface area of 300 m 2 /g in concrete mixtures. Various researchers [45][46][47] have reported some different results attributed to the type and surface areas of nano-silica. They found that colloidal, precipitated and pyrogenic nano-silicas are in the form of relatively large aggregates (similar to the results presented previously) and, although applying different dispersion methods could affect their initial aggregation status in water, it could not break them into single particles.…”

Section: Adsorption/desorption Isothermsmentioning

confidence: 99%

Characterization of morphology and texture of several amorphous nano-silica particles used in concrete

Quercia

Lázaro

Geus

et al. 2013

Cement and Concrete Composites

109

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“…It is broadly known that NS accelerates the early cement hydration rate. The mechanism of acceleration has been claimed to be through increasing dissolution of cement particles in the early stage [7][8][9][10]. NS has very high specific surface area compared to the cement grains, and thus it favors superficial dissolution of the cement particles.…”

Section: Introductionmentioning

confidence: 99%

Effects of Nanosilica on Early Age Stages of Cement Hydration

Isfahani

Redaelli

et al. 2017

Journal of Nanomaterials

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Effects of nanosilica on cement hydration have been broadly investigated in the literature and early age cement hydration, as a whole, has been mainly considered, disregarding the substages of the hydration. The hydration of cement is characterized by different substages and nanosilica effect on the hydration could be a result of diverse, even contradictory, behavior of nanosilica in individual stages of the hydration. In this study, effects of nanosilica on different substages of cement hydration are investigated. Isothermal calorimetry results show that at early ages (initial 72 hours) the effects of nanosilica depend on the phenomenon by which the hydration is governed: when the hydration is chemically controlled, that is, during initial reaction, dormant period, and acceleratory period, the hydration rate is accelerated by adding nanosilica; when the hydration is governed by diffusion process, that is, during postacceleratory period, the hydration rate is decelerated by adding nanosilica. The Thermal Gravimetric Analysis on the samples at the hardened state (after 28 days of curing) reveals that, after adding nanosilica, the hydration degree slightly increased compared to the plain paste.

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Influence of nano-silica agglomeration on fresh properties of cement pastes

Cited by 176 publications

References 19 publications

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

Polycarboxylate/nanosilica-modified quaternary cement formulations – enhancements and limitations

Characterization of morphology and texture of several amorphous nano-silica particles used in concrete

Effects of Nanosilica on Early Age Stages of Cement Hydration

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