Combined usage of micro-silica and nano-silica in concrete: SP demand, cementing efficiencies and synergistic effect

Li, L.G.; Zheng, Jun; Zhu, Jiang; Kwan, A.K.H.

doi:10.1016/j.conbuildmat.2018.02.181

Cited by 84 publications

(30 citation statements)

References 41 publications

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“…Li et al also investigated the influence of nanosilica [Li et al, 2018]. These authors studied the concretes with the addition of both ordinary microsilica and nanosilica.…”

Section: Journal Of Ecological Engineeringmentioning

confidence: 99%

The Influence of Silica Fume on the Mechanical and Thermal Parameters of Portland Cement Concretes

Strzałkowski¹,

Garbalińska²

2019

J. Ecol. Eng.

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The influence of the silica fume (SF) addition on the basic mechanical and thermal parameters of cement concrete was presented in this paper. Numerous studies show that the specific properties of silica fume allow producing concretes with increased strength and durability properties. However, the results of the authors' own studies demonstrated that under specific circumstances, the SF addition can negatively affect the strength of cement concrete. In this paper, the concretes made from two types of coarse aggregate, 4-8 mm fraction: reference ordinary gravel aggregate (Ref) and broken basalt aggregate (Bas) were tested. Comprehensive tests (microstructural, strength and thermal) were carried out on three formulas: the first one (Ref-0) did not contain any additives or admixtures. Silica fume and superplasticizer were used in the second formula (Ref-8), introduced in the amount of 8% and 0.75% of the cement's weight, respectively. The third formula, based on basalt aggregate (Bas-8), also contained silica fume and a superplasticizer, dosed in the same amount as in the second formula. Porosimetric studies showed that the use of silica fume in the Ref-8 formula resulted in a decrease in the number of pores smaller than 0.15 μm in comparison to the Ref-0 reference concrete without the silica fume. On the other hand, numerous additional pores with diameters ranging from 0.05 to 300 μm were found in the Bas-8 concrete. In turn, optical porosimetry proved that the basalt-based concrete had numerous pores in the range above 70 μm, which were not observed in the case of the concretes with ordinary pebble aggregate. In the case of the normal concrete, the addition of silica fume resulted in an increase in the compressive strength. However, the basalt-based concrete, due to its much higher porosity, achieved significantly lower strength values. The results showed that the observed changes in porosity, caused by the presence of silica fume, resulted in lower values of thermal conductivity and specific heat of mature composites that it had been added to. This was particularly evident for the basalt-based concrete.

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“…Li et al also investigated the influence of nanosilica [Li et al, 2018]. These authors studied the concretes with the addition of both ordinary microsilica and nanosilica.…”

Section: Journal Of Ecological Engineeringmentioning

confidence: 99%

The Influence of Silica Fume on the Mechanical and Thermal Parameters of Portland Cement Concretes

Strzałkowski¹,

Garbalińska²

2019

J. Ecol. Eng.

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“…The silica fume has lesser pozzolanic activity and filling ability compared to nano SiO2. Li et al (2018) demonstrated that with both micro silica and nano SiO2 added together, the compressive strength and elastic modulus could be increased to higher than those achievable with only MS added or only NS added. SEM images obtained from the mortar samples 5S, 5S+1NS, 5S+2NS and 5S+3NS are seen in the Fig.…”

Section: Resultsmentioning

confidence: 98%

Effect of nano silica on cement mortars containing micro silica

Kara¹,

Durmuş²

2019

CJCRL

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The use of cement and concrete is becoming increasingly widespread all over the world. However, the high energy consumption required for the production of clinker and the greenhouse gas emissions generated during production negatively affect both the economy and the environment. In the studies conducted for many years, researchers have found that the substitution of various pozzolans with cement provides both technical advantages and environmental benefits. The use of pozzolans in cementitious composites provides advantages such as the improvement of the physical and mechanical properties of the material, the conservation of the environment and the economy in terms of the evaluation of industrial wastes. In recent years, studies on the use of nanoparticles in cementitious composites are positively. In this study, it was aimed to investigate the properties of fresh and hardened cement mortars using micro silica as pozzolan and nano silica as nanoparticle. For this purpose, four different cement pastes and mortars mixtures were prepared by substituting 0%, 1%, 2%, 3% nano SiO2 (silica) cement in mortar mixtures containing 5% micro silica. The effects of the nano silica on the micro silica-containing cement paste on the consistency and setting time were investigated. The mortar mixtures produced were subjected to flexural and compressive strength tests on days 7, 28 and 90th. SEM images of mortar mixtures were taken. As a result, it was found that 2% nano silica admixture of 5% micro silica containing cement admixture affects the flexural and compressive strength positively, whereas 2% nano silica admixture increased the flexural strength by 13% and compressive strength by 7%.

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“…Chu and Kwan [11] demonstrated that the presence of MK increased the CEF of micro-silica for strength through synergistic effects. Li et al [37,38] demonstrated that the CEF of micro-silica was between 2.07 and 2.80 for strength, between 2.78 to 9.87 for chloride resistance and between 3.34 and 6.50 for sulphate resistance; and, the CEF of nano-silica was between 4.30 and 6.05 for strength, between 4.76 to 12.01 for chloride resistance and between 6.75 and 22.06 for sulphate resistance.…”

Section: Extension Of Cef To Fresh Propertiesmentioning

confidence: 99%

“…On the other hand, for quantitative evaluation of the cementing efficiency of a SCM, the concept of cementing efficiency factor (CEF), which is defined as the mass of cement that can be substituted per unit mass of SCM added without affecting the strength or durability attribute under investigation, has been advocated for years [27][28][29]. This concept has been applied to evaluate the cementing efficiencies of various SCMs solely with respect to the strength and durability performances [11,[30][31][32][33][34][35][36][37][38]. Herein, as the effects of the SCM on the workability and cohesiveness will also be investigated, the term "cementing efficiency factor" is changed to "cement equivalent factor" because the workability and cohesiveness are un-related to the cementing efficiencies.…”

Section: Introductionmentioning

confidence: 99%

Cement Equivalence of Metakaolin for Workability, Cohesiveness, Strength and Sorptivity of Concrete

Chen

et al. 2020

Materials

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A series of concrete mixes with metakaolin (MK) content ranging from 0 to 30% and water/cementitious materials (W/CM) ratio varying from 0.30 to 0.50 were produced for performance testing. The results showed that adding MK up to 20% as ordinary Portland cement (OPC) replacement best improved the 28-day and 70-day cube strengths, whereas adding MK up to 30% as OPC replacement always increased the cohesiveness and decreased the sorptivity, but impaired the workability. Moreover, the cement equivalent factor (CEF), i.e. the equivalent mass of OPC per mass of MK added, for each performance attribute, including workability and cohesiveness, was evaluated. Whilst the actual CEF of MK was generally higher at a higher W/CM ratio and lower at a higher MK content, overall, the average CEFs were found to be 1.98, 2.17, 3.83, 1.93, 2.12, and 4.70 for slump, flow, cohesiveness, 28-day cube strength, 70-day cube strength, and sorptivity coefficient, respectively. These CEF values indicated that the MK is a highly effective cementitious material for improving the cohesiveness, strength, and durability. Moreover, it has been demonstrated that the CEFs for workability and cohesiveness are useful parameters in aiding the mix design of MK concrete.

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Combined usage of micro-silica and nano-silica in concrete: SP demand, cementing efficiencies and synergistic effect

Cited by 84 publications

References 41 publications

The Influence of Silica Fume on the Mechanical and Thermal Parameters of Portland Cement Concretes

The Influence of Silica Fume on the Mechanical and Thermal Parameters of Portland Cement Concretes

Effect of nano silica on cement mortars containing micro silica

Cement Equivalence of Metakaolin for Workability, Cohesiveness, Strength and Sorptivity of Concrete

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