Combined effect of nano-SiO&lt;sub&gt;2&lt;/sub&gt; and nano-Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt; on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars

Sanjuán, Miguel Ángel; Argiz, Cristina; Gálvez, Jaime C.; Reyes, E.

doi:10.3989/mc.2018.10716

Cited by 16 publications

(8 citation statements)

References 24 publications

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“…Mitchell et al [43] found unreacted silica fume particles in pastes with 5 % of silica fume after 180 days of curing. This supports the low pozzolanic reaction rate of silica fume due to an agglomeration of nanoparticles [44].…”

Section: Mechanical Performance and Open Porositysupporting

confidence: 69%

“…It has been reported higher compressive strength in mortars with nano-SiO 2 particles of 40 nm in size than with particles between 12 and 20 nm due to the agglomeration of the small particles [52]. Therefore, the resulting agglomerates will influence on the filling of the capillary pores [44]. Accordingly, nano-SiO 2 particles in a range of 4-8% in mortars can promote an increase in the total porosity [53,54].…”

Section: Alkali-aggregate Mitigation By Pozzolanic Additions In Cemen...mentioning

confidence: 99%

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Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

et al. 2020

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The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash.

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Section: Mechanical Performance and Open Porositysupporting

confidence: 69%

Section: Alkali-aggregate Mitigation By Pozzolanic Additions In Cemen...mentioning

confidence: 99%

Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

et al. 2020

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“…Moreover, the unreacted NS particles are dispersed in smaller spaces and fill the void, refining the pore structure, and improving the compactness of the concrete. As previously mentioned, NS particles have extremely large specific surface areas, and when the NS added exceeds the optimal dosage, agglomeration phenomena can occur in the mixture [ 64 ]. Simultaneously, the nanoparticles have strong water absorption; accordingly, excessive NS absorbs the water originally required for the cement hydration, resulting in insufficient cement hydration and a decreased strength of the concrete [ 65 ].…”

Section: Resultsmentioning

confidence: 99%

Effect of Nano Silica Particles on Impact Resistance and Durability of Concrete Containing Coal Fly Ash

Zhang

Sha

et al. 2021

Nanomaterials

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In this study, the effect of adding nano-silica (NS) particles on the properties of concrete containing coal fly ash were explored, including the mechanical properties, impact resistance, chloride penetration resistance, and freezing–thawing resistance. The NS particles were added into the concrete at 1%, 2%, 3%, 4%, and 5% of the binder weight. The behavior under an impact load was measured using a drop weight impact method, and the number of blows and impact energy difference was used to assess the impact resistance of the specimens. The durability of the concrete includes its chloride penetration and freezing–thawing resistance; these were calculated based on the chloride diffusion coefficient and relative dynamic elastic modulus (RDEM) of the samples after the freezing–thawing cycles, respectively. The experimental results showed that the addition of NS can considerably improve the mechanical properties of concrete, along with its freezing–thawing resistance and chloride penetration resistance. When NS particles were added at different replacement levels, the compressive, flexural, and splitting tensile strengths of the specimens were increased by 15.5%, 27.3%, and 19%, respectively, as compared with a control concrete. The addition of NS enhanced the impact resistance of the concrete, although the brittleness characteristics of the concrete did not change. When the content of the NS particles was 2%, the number of first crack impacts reached a maximum of 37, 23.3% higher compared with the control concrete. Simultaneously, the chloride penetration resistance and freezing–thawing resistance of the samples increased dramatically. The optimal level of cement replacement by NS in concrete for achieving the best impact resistance and durability was 2–3 wt%. It was found that when the percentage of the NS in the cement paste was excessively high, the improvement from adding NS to the properties of the concrete were reduced, and could even lead to negative impacts on the impact resistance and durability of the concrete.

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“…Dried and hardened cement paste and mortar have an electrical resistivity of approximately 104–107 Ω·m [36], which is decided by the constituents of cement, humidity, w/c ratio, etc., [37,38]. The resistivity of electrically conductive concrete is under 100 Ω·m [39], depending upon the electronic conduction within the conductive materials, such as steel fibers and graphite.…”

Section: Resultsmentioning

confidence: 99%

The Influence of Water/Cement Ratio and Air Entrainment on the Electric Resistivity of Ionically Conductive Mortar

et al. 2019

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Ionically-conductive mortar can be used for indoor radiant heating partition walls. In these applications, mortar blocks are soaked in electrolyte solutions of CuSO4. The surfaces of the block are coated with sealant and epoxy resin afterwards to prevent evaporation. The mortar block becomes a heating element due to ionic conduction if a voltage is applied to the electrodes in the block. Its electrical conductivity depends on the dispersion of the electrolyte, and hence on the porosity of the mortar. The test specimens in this study were divided into four groups according to the different air entrainment agents, including aluminum powder and hydrogen peroxide as well as two air-entraining agents, SJ-2 and K12. Each group was manufactured with water/cement ratios in the range of 0.5 to 0.9. The test results showed that the conductivity of the mortar was strongly influenced by the air-entrainment and the water cement ratios. The volumetric electric resistivity and the associated microstructures of the mortar were investigated. The test results showed that the specimens made with aluminum powder and a water–cement ratio of 0.65–0.75 had high porosity. The porosity of those specimens was further increased by adding two different air-entraining agents. The specimens with aluminum powder and SJ-2, along with a water–cement ratio of 0.7 appeared to be the optimum mixture. Its resistivity was 19.37 Ω·m at 28 days under 25.31% porosity. The experimental results indicate that an ionically-conductive mortar can be produced by combining different air-entrainment agents with variable water-cement ratios to meet a specified electrical heating requirement.

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Combined effect of nano-SiO<sub>2</sub> and nano-Fe<sub>2</sub>O<sub>3</sub> on compressive strength, flexural strength, porosity and electrical resistivity in cement mortars

Cited by 16 publications

References 24 publications

Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

Effect of Nano Silica Particles on Impact Resistance and Durability of Concrete Containing Coal Fly Ash

The Influence of Water/Cement Ratio and Air Entrainment on the Electric Resistivity of Ionically Conductive Mortar

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