The results indicated that fresh geopolymer concrete had short setting time of 28–58 min due to the presence of high calcium content of fly ash. In general, strengths and modulus of elasticity increased with the increase in NaOH concentration. For compressive strength, the optimum Na 2 O content was around 12% of fly ash. The high-strength ...

Fly ash is an extremely fine powder consisting of spherical particles less than 50 microns in size. Fly ash is one of the construction industry's most commonly used pozzolans. Pozzolans are siliceous or siliceous/alumina materials possessing the ability to form cementitious compounds when mixed with lime (calcium hydroxide, or Ca(OH) 2) and water. Fly Ash: …

Despite a low chemical reactivity, recent trends in the innovative uses of coal fly ash based on the chemical properties have been successful. Lots of fly ash showing sharply alkaline reaction (water pH rising to 11–12 upon contact) usually are high-calcium (>3–4%), most of which is present as CaO.

Using a Novel Fly Ash Based Calcium Silicate as a Potential Paper Filler. ... Its brightness is normally below 30% ISO, (Sinha 2008; Fan and Qian 2012) and its color can range from gray to black. Fly ash contains 35% to 70% SiO 2, 15% to 30% Al 2 O 3, 1% to 10% CaO, 5% to 10% Fe 2 O 3, 1% to 2% TiO 2, and small amounts of other oxides such as ...

This study presents the properties of a recycled aggregate geopolymer mortar made with a blend of high-calcium fly ash (HCF) and low-calcium fly ash (LCF). An experimental study was divided into two series. In series I, an effort was made to produce a more durable HCF geopolymer by partially replacing a portion of the HCF with LCF.

Fly ash is a byproduct from burning pulverized coal in electric power generating plants. During combustion, mineral impurities in the coal (clay, feldspar, quartz, and shale) fuse in suspension and float out of the combustion chamber with the exhaust gases. As the fused material rises, it cools and solidifies into spherical glassy particles ...

Therefore, the effect of chemical admixtures on the properties of fly ash geopolymer was studied to overcome the rapid set of the geopolymer in this paper. High-calcium fly ash and alkaline solution were used as starting materials to synthesize the geopolymer. Calcium chloride, calcium sulfate, sodium sulfate, and sucrose at dosages of 1wt% and ...

The effect of fineness of fly ash on the setting time of geopolymer paste, workability, strength development, and drying shrinkage of geopolymer mortars made from classified fine high-calcium fly ash was investigated. Air-classified fly ash with three different finenesses—coarse original fly ash (CFA), medium-fineness fly ash (MFA), and fine ...

Fly Ash, Slag, Silica Fume, and Natural Pozzolans Fly ash, ground granulated blast-furnace slag, silica fume, ... between 1.9 and 2.8 and the color is generally gray or tan. ASTM C 618 (AASHTO M 295) Class F and Class C fly ... Class C materials are often high-calcium (10% to 30% CaO) fly ashes with carbon contents less than 2%.

Low-calcium Fly ash-based alkali-activated materials (AAM) have some extraordinary properties such as high fire resistance and low shrinkage. However, they have lower strength and high setting time when curing at ambient temperature conditions. Therefore, this research aimed to improve the strength and setting time of low-calcium fly ash-based AAM curing at ambient …

Table 5.1 shows the chemical composition of two different fly ashes: a low-calcium fly ash produced from burning bituminous coal and a high-calcium fly ash from a subbituminous coal. Fly ashes are commonly encountered in compositions between the two examples shown in the table. Fig. 5.1 shows X-ray diffraction patterns for a low- and high-calcium fly ash, indicating …

In this research effort, the role of calcium in geopolymers was investigated through a series of syntheses where a high-calcium fly ash was blended with a low-calcium fly ash. Increased calcium content led to accelerated set-up times, increased compressive strength, and increased product formation. Powder X-ray diffraction results showed the majority of that …

：. In this paper, the synthesis of high-strength geopolymer using fine high-calcium fly ash was studied. The effect of fineness of fly ash on the setting time of geopolymer paste, workability, strength development, and drying shrinkage of geopolymer mortars made from classified fine high-calcium fly ash was investigated.

In the present research, the ultrasonic pulse velocity (UPV) and rebound hammer number (RHN) are employed to assess the age-dependent compressive strength of low calcium fly ash concrete. Simultaneously, the results are compared with the compressive strength obtained through compression tests. The concrete cylinders having dimensions of 100 × 200 …

This paper reports the correlation between existing standards for concrete and the major mechanical properties of geopolymer concrete produced from a range of low-calcium, Class F fly ashes. The data were collected at set points over a 1-year period and include four different sources of fly ash used in the manufacturing of geopolymer concrete.

This concrete uses no Portland cement; instead, we use the low-calcium fly ash from a local coal burning power station as a source material to make the binder necessary to manufacture concrete. Concrete usage around the globe is second only to water. An important ingredient in the conventional concrete is the Portland cement.

Waste minimization is a major approach whereby many industries decrease environmental pollution and promote cleaner production. To achieve sustainable development, a novel idea is proposed herein to recycle magnesium slag (MS) and high-calcium fly ash (FA) into cementitious materials which are then mixed with aeolian sand (AS) to produce a type of paste …

The goal of this investigation is to study dry and moist carbonation of a high calcium fly ash. The process is maintained at 3 different temperatures: 160, 220 and 290 ⁰C and at pressure range of CO 2 and water vapor from 1 to 6 bars. The accelerating effects of the temperature, pressure and water vapor on

High-calcium fly ash concrete. Cite. Download. Patent: CN-101898883-B: Inventor: WEN YANG. WANG JUN. RIXU ZHAO. KEPING SUN. JING WU. More... Assignee: CSCEC COMMERCIAL CONCRETE CO. CHINA CONSTR 3RD ENG BUREAU CO. Dates: Grant . 2012/07/04. Priority . 2010/08/06. This web page summarizes information in PubChem about …

To understand the formation mechanism of high-calcium fly ashes, the mineralogical, physical, and chemical properties of several high calcium fly ashes and their different density fractions (<1.0, 1.0−2.5, 2.5−2.89, and >2.89 g/cm3) from a coal-fired power plant were characterized by X-ray diffractometry (XRD), field scanning electron microscopy …

High calcium fly ash concrete is an important research direction in the field of green building materials. The application of high-calcium fly ash with industrial waste residue properties in the concrete industry can not only solve its difficult problem, but also reduce the energy consumption required for cement-based materials and reduce environmental pollution.

The development of GPC become a major interest to use for in-situ and precast applications. The present study aims to develop High calcium fly ash based GPC with aid of alkaline liquids such as sodium Hydroxide (NaOH) and Sodium silicate (Na 2 SiO 3). Different molarities i.e 4M, 6M, 8M and 10M are used to develop the GPC under ambient and oven ...

The materials used are a commercial CSA clinker, a thermal anhydrite and a siliceous fly ash according to EN 450-1. The measured chemical composition and the phase contents as determined by X-ray diffraction using Rietveld refinement are presented in Table 1.The average composition of the amorphous part of the fly ash was calculated based on the bulk oxide …

This study presents the properties of a recycled aggregate geopolymer mortar made with a blend of high-calcium fly ash (HCF) and low-calcium fly ash (LCF). An experimental study was divided into two series. In series I, an effort was made to produce a more durable HCF geopolymer by partially replacing a portion of the HCF with LCF.

2.4.1 Size, Shape and Colour. Fly ash particle size is finer than ordinary Portland cement. Fly ash consists of silt sized particles, which are generally spherical in nature and their size typically ranges between 1 and 100 µm. ... The effect of low-calcium fly ash on the pore size distribution at the ages of 28 days and 1 year for pastes with ...

This work presents a study of cenosphere separation from lignite high-calcium (~24 wt.%) fly ash by centrifugal method; this is the first report for Mae Moh, Thailand, fly ash with this high calcium content using this technique. The effect of centrifugal parameters on cenosphere yield and properties were investigated. Those properties include physical properties, …

The fly ash used in this study was from Hubei, China. The 45 μm sieve residue of the fly ash was 13.4%, and the chemical composition was shown in Table 1.The industrial water glass used was from the Zhongyuan Maoyuan Sodium Alkaline Plant, China, with SiO 2 accounts for 26.8 wt% and Na 2 O accounts for 8.5 wt%. The reagents NaOH, CaSO 4 and Ca(OH) 2 used …