آخرین محصولات

ASTM C618 Fly Ash Specification: Comparison with Other

However, the quantity of fly ash needed for alkali-silica reaction prevention depends on various concrete mixture parameters, including aggregate source and OPC alkali content, as well as …

Alkaline Activation of Fly Ash: An Overview

The alkali activation of fly ash has become an important area of research because it is possible to use these materials to synthesize inexpensive and ecologically ... Fly ashes having high content of toxins/ heavy metals may be used deposited under expert advice. The environment

Properties of alkali-activated fly ashes determined from …

A first approach to the rheological behaviour of pastes made of fly ashes and concentrated alkaline solutions has been carried out. As in Portland cement pastes, alkaline fly ash systems can be described by means of the Bingham model. Additionally, the treatment of the rheological data has provided information on the kinetics of reaction of these systems at very …

What is Fly Ash? Physical and Chemical Properties of Fly Ash

Fly ash, a byproduct from coal-based thermal power plants, is abundantly available in India. Estimates show that more than 100 million tons of fly ash are produced annually from around 83 major coal-based power stations. ... Unlike Class F, self-cementing Class C fly ash doesn't require an activator. Alkali and sulfate (SO 2) content are ...

Alkali-silica reaction in waterglass-activated slag mortars

Both fly ash and metakaolin can mitigate ASR of the waterglass-activated slag mortars. The optimum dosage of the fly ash for controlling the ASR of the alkali-activated mortars is found to be 30%. The expansion decreases with the increase of the amount of metakaolin. The expansion is completely suppressed when the slag is replaced by 70% ...

Using Class C Fly Ash to Mitigate Alkali Silica Reactions …

reported that the finer the fly ash, the better at reducing ASR. 6 9 The chemistry of the fly ash has also been used as a predictor for ASR mitigation 5, 10, 11 with success. The mineralogy of fly ash is a bit more difficult to use as a predictor for several reasons but has been shown to be important in many ar eas of fly ash utilization.

Temperature rise and initial shrinkage of alkali-activated fly ash

Content: wt% 55·8 1·6 30·3 3·9 1·1 4·1 0·2 0·8 0·4 0·9 Advances in Cement Research Volume 28 Issue 1 Temperature rise and initial shrinkage of alkali-activated fly ash cement pastes Shekhovtsova, Kovtun and Kearsley content of the alkali-activated fly ash cement pastes was calculated as the sodium oxide percentage of fly ash mass (3% ...

Solidification of MSWI fly ash using sodium-montmorillonite …

MSWI fly ash was collected from the waste incineration power plant in Dalian, China. MT was obtained from Zhejiang Fenghong New Materials Co., Ltd. Chemical and mineral composition of raw materials are listed in Table 1 and plotted in Fig. 1, respectively.The dominant chemical composition in MSWI fly ash was CaO, Cl, SO 3, Na 2 O and K 2 O, and MT was …

Effects of modulus ratio and dosage of alkali …

This study investigates the properties and micro-structural characteristics of alkali-activated fly ash (AAFA) mortars. Sodium oxide (Na 2 O) dosages of 121 and 150 kg/m 3 and liquid sodium silicate with alkaline …

What is the difference between slag and fly ash?

The content of fly ash is usually controlled between 20% and 30%. Slag powder is a by-product of the ironmaking process, and the entire process is strictly controlled, so its chemical composition remains relatively stable even if the source of raw materials fluctuates. Fly ash is a by-product of pulverized coal combustion in coal-fired power ...

Characterization of a fly ash-based hybrid well cement …

This effect can be attributed to the pozzolanic reaction in the hybrid alkaline cement system, which enhances the incorporation of aluminum from the fly ash into the gel products; iii)Conversely, at a curing temperature of 50°C, the FCN group shows a higher content of Q 0 and a lower content of Q 1, Q 2 (1Al), and Q 3 (1Al) than the FC group ...

Coal Fly Ash

Fly ash, especially Class F fly ash, is effective in three ways in substantially reducing alkali-silica expansion: 1) it produces a denser, less permeable concrete; 2) when …

Synthesis of alkali-activated materials blended with fly ash

In contrast, olive pomace fly ash exhibits a substantial silica content (31.42 %), a moderate quantity of aluminum (2.06 %), with notable occurrences of sodium (4.86 %), potassium (5.81 %), and calcium (23.99 %). ... due to the high calcium content present in olive pomace fly ash, the term "alkali-activated materials" is used in this study ...

Electrochemical behavior of zinc in alkali-activated fly ash …

The alkali-activated fly ash extract solution (AAFA solution) was prepared by mixing fly ash and a specific activator with the mass ratio of 1:1. ... and corrosion initiation in reinforced alkali-activated mortars: role of calcium, alkali, and silicate content. Cement Concr. Res., 111 (2018), pp. 56-71. View PDF View article View in Scopus ...

Effect of Fly Ash on Alkali-Silica Reactivity in Concrete

IP cement with a Class F fly ash that had an available alkali content of 0.50 percent. This investigation included fly ash from nine different sources. Five fly ashes were Class C and four were Class F as defined by ASTM C618. These fly ashes are presented in Table 2. Seven fly ash sources were selected on the basis of their clas­

Using Class C Fly Ash to Mitigate Alkali Silica Reactions …

mitigation when 25% of high-alkali cem ent was replaced with Class C fly ash. Lenke and Malvar 5 report that there are three characte ristics of a fly ash that determine its efficiency in …

Compaction Properties of Alkali-Activated Fly Ash and Slag …

Since fly ash and slag are both industrial by-products, utilizing them for chemical activation also promote the sustainability aspects of one-part geopolymer. Precursor dosage was chosen to be equivalent blends of fly ash and slag with total precursor dosage of up to 30% by mass (5%FA + 5%S, 10%FA + 10%S, or 15%FA + 15%S).

Alkali Content of Fly Ash – Measuring and Testing …

Relationship between total alkali and available alkali for fly ash High-alkali fly ash from Ottumwa Generating Station was not conclusively linked to ASR problems at any field site. It was used in pavements that had both good and poor performance. Sites 2, 5 and 9 all contained OGS fly ash but did not exhibit significant

The importance of the network-modifying element content in fly ash …

The coal fly ashes were alkali activated with 5 M (denoted '5M' in the sample label) and 10 M (denoted '10M' in the sample label) NaOH solutions made from analytical grade NaOH pellets (Sigma–Aldrich).To obtain appropriate consistency of all the pastes, the solution to solid binder weight ratio (s/b) of the samples was set to 0.6.

Early strength development and hydration of alkali-activated …

This study concerns the effect of two types of fly ash and the addition of lime on the strength development and hydration of sodium hydroxide- and sodium silicate-activated slag/fly ash blends which consisted of 50% fly ash and 50% slag by mass. Performance was compared to that of slag cements. When NaOH was used as an activator, the slag replacement …

Effect of 60 °C sustained temperature conditions on the …

Related References Çelikten, S.; Sarıdemir, M.; Özgür Deneme, . 2019: Mechanical and microstructural properties of alkali-activated slag and slag + fly ash mortars exposed to high temperature Construction and Building Materials 217: 50-61

New insights into the role of fly ash in mitigating alkali-silica

It is observed that the content of Al 2 O 3 in fly ash was 17.28% or 4.4 and 2.9 times higher than the levels found in the ASTM C150 Type II and high alkali cements, respectively. …

[PDF] Workability and mechanical properties of alkali-activated fly ash

DOI: 10.1016/J.CONBUILDMAT.2018.04.008 Corpus ID: 4710749; Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature @article{Fang2018WorkabilityAM, title={Workability and mechanical properties of alkali-activated fly ash-slag concrete cured at ambient temperature}, author={Guohao Fang and Wing Kei Ho …

Alkali Content of Fly Ash – Measuring and Testing Strategies …

Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the …

Efficient use of steel slag in alkali-activated fly ash-steel slag

A study on the corrosion of reinforcing bars in alkali-activated fly ash mortars under wet and dry exposures to chloride solutions. Cem. Concr. Res., 87 (2016), pp. 53-63. View PDF View article View in Scopus ... Influence of fly ash content on alkalinity of pore solution and microstructure of cement pastes. J. Build. Mater., 13 (6) (2010), pp ...

Alkali-activated fly ash matrices for lead immobilisation: a …

The present paper reports on the lead stabilisation capacity of certain new containment systems, in which fly ash from steam power plants is activated (made to set and harden) with high-alkalinity solutions. Lead is immobilised in such systems because it is precipitated as a highly insoluble silicate. Results are reported from various leaching trials …

Aggregates Obtained by Alkali Activation of Fly Ash: The …

On the other hand, alkali-activated fly ash synthesized by an alkali activator comprising a higher content of silicon, and consequently a higher Si/Al ratio (Si/Al > 1.6), will enable the incorporation of a substantial amount of dissolved aluminum into the aluminosilicate oligomers which are consumed upon alkali activation and the formation of ...

Investigation on enhancing the mechanical properties of Alkali

Additionally, the alkali content in fly ash, including compounds like sodium oxide (Na 2 O) and potassium oxide (K 2 O), required careful consideration when incorporating it into AAC, as it impacted the reaction with alkaline activators. These chemical characteristics were carefully considered to optimize the performance of fly ash in AAC ...

Optimizing the content of Li2CO3, Na2SO4 and TEA in fly ash…

DOI: 10.1016/j.conbuildmat.2024.138837 Corpus ID: 273538073; Optimizing the content of Li2CO3, Na2SO4 and TEA in fly ash–cement system by response surface methodology @article{Chen2024OptimizingTC, title={Optimizing the content of Li2CO3, Na2SO4 and TEA in fly ash–cement system by response surface methodology}, author={Jixi Chen and …

Alkali Content of Fly Ash Measuring and Testing …

Sodium and potassium are the common alkalis present in fly ash. Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the …

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