Fly ash alkali content

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 effectiveness of the fly ash to mitigate alkali-silica reaction (ASR). The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for execution and …

Verification of the mutually complementary effect of fly …

However, there is a risk of ASR in using CL due to the alkali leaching from the CL. Therefore, the combined use of fly ash and CL may have a synergistic effect. Based on these considerations, we examined the effect of using fly ash and CL in combination on the internal temperature of mortar, strength development, and ASR.

Preparation and properties of fly ash-based geopolymer …

2020-4-8 · The aim of the research was to investigate the influences of high alkaline content foundry sand regeneration wastes incorporated with fly ash in the production of geopolymer concrete. The fly ash-based geopolymer concrete was activated using alkaline solutions of sodium silicate and sodium hydroxide. The geopolymeric products were characterized using X …

Alkali content of fly ash : measuring and testing strategies …

1  · This study investigated the test methods used to determine the alkali content of fly ash. It also evaluated if high-alkali fly ash exacerbates alkali-silica reaction in …

A Ten-Year Study on Alkali Content of Coal Fly Ash

2022-5-17 · The alkali content refers to the content of Na 2 O and K 2 O in cement. In almost all cases, the percentages were lower than 2% and most of the samples displayed percentages lower than 1%. Figure 2. Maximum, minimum, and average values of Na 2 O, K 2 O, and Na 2 O e in coal fly ash.

Role of Fly Ash Particle Size on Alkali Thermal Activation …

2022-1-1 · Different specimens, made from a mixture of fly ash and rice husk bark ash in fine and coarse forms, together with alkali activator made (a solution of …

Determination of Potassium, Sodium, and Total Alkalies in …

2011-6-21 · A simple flow injection with flame photometric detection has been developed for determination of sodium, potassium, and total alkalies in portland cement, fly ash, admixtures, and water of concrete. A liquid sample or a digest of solid sample was injected into a water carrier stream which flowed to a flame photometer. A change in emission intensity at a selected …

Chemical and Microstructural Properties of Fly Ash and Fly …

2022-5-29 · The micrographs of alkali-activated neat fly ash and 60%/40% fly ash/slag pastes are shown in Figure 5. The WG-based activator seems to allow a satisfactory dissolution of raw materials, not hindering the polycondensation rate during the geopolymer synthesis and allowing the maximum geopolymer gel formation which is visible in Figure 5 b.

Coal fly ash alkalis content characterization by means of a …

2016-2-1 · Three factors and 2 levels were fixed in the full factorial design. Then, it requires a total of 8 experiments in the case of a 2 3 design. This type is found adequated to determine the effects of free CaO, reactive silica and fineness (Residue on 45 µm) on alkali content in coal fly ash.The levels selected were 0.5% and 1.0% of free CaO, 30% and 40% of reactive silica and …

A Ten-Year Study on Alkali Content of Coal Fly Ash

2022-5-17 · This applied research has been done to verify previously done research. The scope of this paper is to assess the alkaline content of coal fly ash over a period of 10 years. The Na 2 O-equivalent of coal fly ash ranged from 0.35% to 2.53%, with an average value of 0.79%. These values should be taken into account producing concretes made with ...

Clean Coal Technology

Adding a small amount of water(~2%) and a small amount of alkali(≤2%) to fly ash can reduce the mass fraction of ammonia in fly ash to less than 100 mg/kg. Due to the small amount of water added, the flue gas can be dried after desulfurization of the subsequent unit, and the NH_3 generated in the treatment process can be re injected into the SCR Flue gas denitration device …

Effects of Solid Activator and Fly Ash on Rheology and …

Compared with conventional two-part alkali-activated materials (AAMs), one-part AAMs have several advantages, especially the simple production using only water similar to ordinary Portland cement. ... The effects of solid activator content, besides the effect of two types of fly ash (containing different amounts of carbonaceous impurities) with ...

A comparison between alkali‐activated slag/fly ash binders …

2022-4-25 · Among all types of AAMs, alkali-activated slag/fly ash (AASF)-blended binders are gaining increasing attention because of their unique advantages over single-source-based systems, such as reasonable setting time and higher durability in acidic environments. 31-36 However, related literature regarding the effect of SW on AASF binders is quite ...

Alkalis Content

2016-2-1 · Three factors and 2 levels were fixed in the full factorial design. Then, it requires a total of 8 experiments in the case of a 2 3 design. This type is found adequated to determine the effects of free CaO, reactive silica and fineness (Residue on 45 µm) on alkali content in coal fly ash.The levels selected were 0.5% and 1.0% of free CaO, 30% and 40% of reactive silica and …

What is the difference between slag and fly ash?

2022-6-24 · 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 ...

Alkalis Content

The decrease in the alkali content of the pore solution is parallel with the increase in the alkali content of the solid phases (Figure 10.89). 476 Pozzolana reduces the C/S ratio of C-S-H and this allows more alkalis to be incorporated in calcium silicate hydrates (Figure 10.90). 480 About 95 per cent of the total alkali content can be retained by blended cement pastes, where only ∼ 15 …

Alkali Content of Fly Ash – Measuring and Testing …

2015-5-29 · contained moderately reactive fine aggregate and high-alkali fly ash from Ottumwa Generating Station (OGS). A total of nine pavement sites were selected to be evaluated. This study investigated the test methods used to determine the alkali content of fly ash. It also evaluated if high-alkali fly ash exacerbates alkali-silica reaction in ...

Final Report April 2015

2015-5-29 · Excessive amounts of fly ash alkalis can cause efflorescence problems in concrete products and raise concern about the effectiveness of the fly ash to mitigate alkali-silica reaction (ASR). The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for execution and reporting.

Behavior of Alkali-Activated Fly Ash through Underwater …

Class C fly ash as source materials, sodium silicate, and sodium hydroxide solution as alkaline activator were used for this study. Specimens produced through underwater placement in seawater showed impressive performance with strength 71.10 MPa on 28 days.

Alkali content in fly ash with different soaking time.

The former Yuan team of North China Electric Power University concluded that the specific resistance value of coal-fired fly ash decreases with the increase in …

Influence of Different Parameters on the Performance of …

2022-4-7 · At the 5% significance level, the F values of fly ash content, water glass modulus, water glass solid content, and water–solid ratio were 10.688, 2.085, 13.919, and 1.062, respectively. The F values of fly ash content and water glass solid content were significantly higher than those of the other two factors.

Alkali Content of Fly Ash – Measuring and Testing …

2018-4-18 · strong (linear) relationship was observed between available alkali content and total alkali content of Class C fly ash. This relationship can be used to provide a quicker, more precise method of estimating the available alkali content. The results of the field study failed to link the use of high-alkali fly ash with the occurrence of

Chemical and Microstructural Properties of Fly Ash and Fly …

2022-5-29 · Sodium silicate is commonly used for activating alumina silicates to produce alkali-activated binders that can compete with conventional Portland cement in concrete. However, the cost and emissions related to activators can hinder the use of alkali-activated materials in the industry. The novel, waste-based activators have been developed in the last years, using Si …

Fly Ash Characterization

For example, for PCP1 with a 20 percent fly ash replacement (FAR) level, the NIST model was used to estimate the PSA (0.11M Na + and 0.27M K +) corresponding to 80 percent cement. The ASTM C311-based available alkali for fly ash was 0.03M Na + and 0.07M K +.

[PDF] Thermal behavior of alkali-activated fly ash/slag with …

2020-2-1 · DOI: 10.1016/j.cemconcomp.2019.103462 Corpus ID: 210234602; Thermal behavior of alkali-activated fly ash/slag with the addition of an aerogel as an aggregate replacement @article{Seo2020ThermalBO, title={Thermal behavior of alkali-activated fly ash/slag with the addition of an aerogel as an aggregate replacement}, author={J. H. Seo and Seong Jun Bae …

Coal fly ash alkalis content characterization by means of a …

2015-11-1 · The scope of this paper is to assess the alkaline content of coal fly ash over a period of 10 years. The Na2O-equivalent of coal fly ash ranged from …

Alkaline Activation of Fly Ash: An Overview

2018-11-21 · 1.3 Alkali Treated Fly Ash /Other Binders Fernandez- Jimenez et al. (2005) conducted a study to determine the relationship between the mineralogical and microstructural characteristics of alkaline activated fly ash mortars. The activation of fly ash provides a material with cementing features comparable than that of OPC. In the

Alkali Content of Fly Ash – Measuring and Testing …

The available alkali test, which is commonly used to measure fly ash alkali, takes approximately 35 days for execution and reporting. Hence, in many instances the fly ash has already been incorporated into concrete before the test results are available. This complicates the job of the fly ash marketing agencies and it leads to disputes with fly ...

Multi Expression Programming Model for Strength …

2022-6-6 · Rapid industrialization is leading to the pollution of underground natural soil by alkali concentration which may cause problems for the existing expansive soil in the form of producing expanding lattices. This research investigates the effect of stabilizing alkali-contaminated soil by using fly ash. The influence of alkali concentration (2 N and 4 N) and curing period (up to 28 …

Alkali-Activated Hybrid Concrete Based on Fly Ash and …

2020-10-26 · alkaline activation of FA (type F) of Colombian origin, supplemented with 10% (by weight) of OPC. Concrete production was based on the development and characterization of a hybrid cement, whose composition and synthesis were optimized by varying the content of alkaline activator (NaOH + Na2SiO3). The hybrid cement was characterized by ...