Microstructure and phase characterizations of fly ash cements by alkali activation

Sanchindapong, Sak; Narattha, Chalermphan; Piyaworapaiboon, Manow; Sinthupinyo, Sakprayut; Chindaprasirt, Prinya; Chaipanich, Arnon

doi:10.1007/s10973-020-10021-5

Cited by 11 publications

(3 citation statements)

References 32 publications

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“…The nature of the activator also affected early-age strength development at ambient temperature. The H-WG T25-2 pastes exhibited greater strength than the HN T25-2 pastes due to the extra soluble silica (sourced from the WG) in the medium and the early formation of reaction product [53,57,58]. As expected, an inverse relationship was observed between compressive strength and mean pore size (see Table 5), a finding consistent with earlier reports [59][60][61].…”

Section: Hybrid Cement Paste Compressive Strength and Mean Size Poresupporting

confidence: 90%

Hybrid Cements: Mechanical Properties, Microstructure and Radiological Behavior

et al. 2022

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The use of more eco-efficient cements in concretes is one of the keys to ensuring construction industry sustainability. Such eco-efficient binders often contain large but variable proportions of industrial waste or by-products in their composition, many of which may be naturally occurring radioactive materials (NORMs). This study explored the application of a new gamma spectrometric method for measuring radionuclide activity in hybrid alkali-activated cements from solid 5 cm cubic specimens rather than powder samples. The research involved assessing the effect of significant variables such as the nature of the alkaline activator, reaction time and curing conditions to relate the microstructures identified to the radiological behavior observed. The findings showed that varying the inputs generated pastes with similar reaction products (C-S-H, C-A-S-H and (N,C)-A-S-H) but different microstructures. The new gamma spectrometric method for measuring radioactivity in solid 5 cm cubic specimens in alkaline pastes was found to be valid. The variables involved in hybrid cement activation were shown to have no impact on specimen radioactive content. The powder samples, however, emanated 222Rn (a descendent of 226Ra), possibly due to the deformation taking place in fly ash structure during alkaline activation. Further research would be required to explain that finding.

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Section: Hybrid Cement Paste Compressive Strength and Mean Size Poresupporting

confidence: 90%

Hybrid Cements: Mechanical Properties, Microstructure and Radiological Behavior

et al. 2022

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“…They used 3, 6 and 9 M sodium hydroxide concentrations for the samples and noticed that samples with the 6 M concentration exhibited higher compressive strength of 22 MPa [ 93 ]. High-calcium, fly-ash-based geopolymers at 70%, 80%, 90% and 100% by mass of binders in combination with OPC and activated by sodium silicate and sodium hydroxide (alkali liquid/binder = 0.65 and Na 2 SiO 3 /NaOH = 0.67) cured at 60 °C showed that samples had increased compressive strength [ 94 ]. Fly-ash-based geopolymer mortar with sodium hydroxide as an activator showed increased compressive strength as compared to the same fly-ash-based geopolymer with a potassium hydroxide activator.…”

Section: Geopolymersmentioning

confidence: 99%

Geopolymers and Fiber-Reinforced Concrete Composites in Civil Engineering

et al. 2021

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This paper discusses the influence of fiber reinforcement on the properties of geopolymer concrete composites, based on fly ash, ground granulated blast furnace slag and metakaolin. Traditional concrete composites are brittle in nature due to low tensile strength. The inclusion of fibrous material alters brittle behavior of concrete along with a significant improvement in mechanical properties i.e., toughness, strain and flexural strength. Ordinary Portland cement (OPC) is mainly used as a binding agent in concrete composites. However, current environmental awareness promotes the use of alternative binders i.e., geopolymers, to replace OPC because in OPC production, significant quantity of CO2 is released that creates environmental pollution. Geopolymer concrete composites have been characterized using a wide range of analytical tools including scanning electron microscopy (SEM) and elemental detection X-ray spectroscopy (EDX). Insight into the physicochemical behavior of geopolymers, their constituents and reinforcement with natural polymeric fibers for the making of concrete composites has been gained. Focus has been given to the use of sisal, jute, basalt and glass fibers.

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“…5) evenly and roasted at high temperature to achieve the purpose of activation. 25,26 However, the process of alkali fusion is usually high cost, high temperature, high energy consumption and low activation efficiency. 27 Therefore, in terms of environment and economy, it is necessary to nd a new activator to further reduce energy consumption.…”

Section: Introductionmentioning

confidence: 99%