scholarly journals A Research on Durability Degradation of Mineral Admixture Concrete

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1752
Author(s):  
Xupeng Chen ◽  
Zhuowen Sun ◽  
Jianyong Pang
Keyword(s):  
Fly Ash ◽  
Circle Method ◽  
Mineral Admixture ◽  
X Ray Diffraction ◽  
Complex Ions ◽  
Sulfate Ions ◽  
X Ray ◽  
Relational Analysis ◽  
Grey Relational ◽  
Compressive Tests

In order to study the degradation laws and mechanisms of admixture concretes with single-added SO42− and composite of Mg2+ and SO42−, respectively, the durability tests were conducted on three types of mineral admixture concretes (concretes with single-added metakaolin (MK), single-added ultra-fine fly ash (UFA), and composite of metakaolin and ultra-fine fly ash (MF), and one reference concrete. In these tests, the 10% Na2SO4 solution and the 10% MgSO4 solution were used as the erosion medium, and the drying-wetting circle method was applied. It can be seen from the compressive tests and grey relational analysis that the MK admixture can improve the anti-Na2SO4-erosion capability of the concrete significantly, but weaken its anti-MgSO4-erosion capability; the UFA admixture can improve both the anti-Na2SO4-erosion and the anti-MgSO4-erosion capability of the concrete; and the composite admixture has superimposed effects and can enhance erosion resistance against these two erosion mediums. The phase composition and the changes of the macro morphology and the micro structure during the erosion process caused by mono sulfate ions and complex ions has been observed through X-ray diffraction (XRD), FTIR spectrum (FTIR), and scanning electron microscope (SEM), based on which it was determined that the erosion of single-added SO42− ions can produce erosive outputs of ettringite, gypsum, and mirabilite in the concrete, and cause corner scaling or deformation. Mg2+ and SO42− reacted in the concrete and produced brucite, M-S-H, ettringite, and gypsum, etc. The erosion of complex ions can cause scaling of the cement mortar and aggregate from the surface or the desquamation of corners.

scholarly journals Influence of Inertia and Low Active Mineral Admixture on Strength and Microstructure of Cement-Based Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Meijuan Rao ◽  
Wan Tang ◽  
Wei Zhou ◽  
Yaning Kong ◽  
Shuhua Liu
Keyword(s):  
Fly Ash ◽  
Early Stage ◽  
Heat Of Hydration ◽  
Mineral Admixture ◽  
Limestone Powder ◽  
Mineral Admixtures ◽  
Inert Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials

Cement-based materials were investigated by comparing the strength and microstructure of pastes and mortar containing limestone powder or low quality fly ash. The compressive strength of the mortar at 28 and 90 d was examined whose microstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, and differential thermal analysis (TG-DTA). The results indicated that the strength of mortar decreased with increasing mineral admixtures. The limestone powder mainly acted as inert filler and hardly took part in the chemical reaction. Low quality fly ash may accelerate the formation of hydration products in samples with more chemically bonded water. This further resulted in a higher degree of cement hydration and denser microstructure, while the overall heat of hydration was reduced. At the early stage of hydration, low quality fly ash can be considered as an inert material whereas its reactivity at the later stage became high, especially for ground low quality fly ash.

scholarly journals Preliminary Study of the Targeted Cleaning of an Artificial Gypsum Layer on White Marble

Coatings ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 37
Author(s):  
Yan Liu ◽  
Taoling Dong ◽  
Kun Zhang ◽  
Fuwei Yang ◽  
Liqin Wang
Keyword(s):  
Electron Microscopy ◽  
Barium Carbonate ◽  
Color Difference ◽  
X Ray Diffraction ◽  
White Marble ◽  
Capillary Suction ◽  
Sulfate Ions ◽  
X Ray ◽  
Preliminary Study ◽  
Scanning Electron

Targeting cleaning of the artificial gypsum layer on white marble was studied. It was conducted by means of the specific depletion of the calcium and sulfate ions by the barium carbonate scavenger, which led to the continuous dissolution and clearance of gypsum layer. The cleaning effect was evaluated by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX), X-ray diffraction (XRD), capillary suction, and color difference measurement. By this method, only the gypsum layer was cleared away and the carbonate substrate of marble was left intact at the same time. This method will be highly useful for the conservation of marble relics from surface weathering.

Physical and Mechanical Properties of Cement Paste Were Used Partially with Fly Ash and Kaolin Waste

2017 ◽  
Vol 866 ◽  
pp. 199-203
Author(s):  
Chidchanok Chainej ◽  
Suparut Narksitipan ◽  
Nittaya Jaitanong
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Room Temperature ◽  
Physical And Mechanical Properties ◽  
Partial Replacement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lime Water ◽  
Diffraction Patterns ◽  
Iron Mold

The aims of this research were study the microstructures and mechanical properties for partial replacement of cement with Fly ash (FA) and kaolin waste (KW). Ordinary Portland cement were partially replaced with FA and KW in the range of 25-35% and 10-25% by weight of cement powder. The kaolin waste was ground for 180 minutes before using. The specimen was packing into an iron mold which sample size of 5×5×5 cm3. Then, the specimens were kept at room temperature for 24 hours and were moist cured in the incubation lime water bath at age of 3 days. After that the specimens were dry cured with plastic wrap at age of 3, 7, 14 and 28 days. After that the compounds were examined by x-ray diffraction patterns (XRD) and the microstructures were examined by scanning electron microscopy (SEM). The compressive strength was then investigated.

Monitoring of Fluctuations in the Physical and Chemical Properties of a High-Calcium Fly Ash

1987 ◽  
Vol 113 ◽  
Author(s):  
Scott Schlorholtz ◽  
Ken Bergeson ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Chemical Properties ◽  
Operating Conditions ◽  
Physical And Chemical Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Morphological Studies ◽  
High Calcium ◽  
Physical And Chemical ◽  
And Chemical Properties

ABSTRACTThe physical and chemical properties of fly ash produced at Ottumwa Generating Station have been monitored since April, 1985. The fly ash is produced from burning a low sulfur, sub-bituminous coal obtained from the Powder River Basin near Gillette, Wyoming. One-hundred and sixty samples of fly ash were obtained during the two year period. All of the samples were subjected to physical testing as specified by ASTM C 311. About one-hundred of the samples were also subjected to a series of tests designed to monitor the self-cementing properties of the fly ash. Many of the fly ash samples were subjected to x-ray diffraction and fluorescence analysis to define the mineralogical and chemical composition of the bulk fly ash as a function of sampling date. Hydration products in selected hardened fly ash pastes, were studied by x-ray diffraction and scanning electron microscopy. The studies indicated that power plant operating conditions influenced the compressive strength of the fly ash paste specimens. Mineralogical and morphological studies of the fly ash pastes indicated that stratlingite formation occurred in the highstrength specimens, while ettringite was the major hydration product evident in the low-strength specimens.

scholarly journals Characterization of Fly Ash Generated from Matla Power Station in Mpumalanga, South Africa

2012 ◽  
Vol 9 (4) ◽  
pp. 1788-1795 ◽  
Author(s):  
Olushola S. Ayanda ◽  
Olalekan S. Fatoki ◽  
Folahan A. Adekola ◽  
Bhekumusa J. Ximba
Keyword(s):  
Fly Ash ◽  
Inductively Coupled Plasma ◽  
Coal Fly Ash ◽  
Harmful Effect ◽  
Point Of Zero Charge ◽  
X Ray Diffraction ◽  
Power Station ◽  
X Ray ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry

In this study, fly ash was obtained from Matla power station and the physicochemical properties investigated. The fly ash was characterized by x-ray fluorescence, x-ray diffraction, scanning electron microscopy, and inductively coupled plasma mass spectrometry. Surface area, particle size, ash and carbon contents, pH, and point of zero charge were also measured. The results showed that the fly ash is alkaline and consists mainly of mullite (Al6Si2O13) and quartz (SiO2). Highly toxic metals As, Sb, Cd, Cr, and Pb as well as metals that are essential to health in trace amounts were also present. The storage and disposal of coal fly ash can thus lead to the release of leached metals into soils, surface and ground waters, find way into the ecological systems and then cause harmful effect to man and its environments.

Influence of Fly Ash on Corrosion Resistance of Refractory Forsterite-Spinel Ceramics

2021 ◽  
Vol 325 ◽  
pp. 181-187
Author(s):  
Martin Nguyen ◽  
Radomír Sokolář
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Corrosion Resistance ◽  
Fly Ash ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transition Zones ◽  
Refractory Ceramics ◽  
Scanning Electron

This article examines the influence of fly ash on corrosion resistance of refractory forsterite-spinel ceramics by molten iron as a corrosive medium. Fly ash in comparison with alumina were used as raw materials and sources of aluminium oxide for synthesis of forsterite-spinel refractory ceramics. Raw materials were milled, mixed in different ratios into two sets of mixtures and sintered at 1550°C for 2 hours. Samples were characterized by X-ray diffraction analysis and thermal dilatometric analysis. Crucibles were then made from the fired ceramic mixtures and fired together with iron at its melting point of 1535°C for 5 hours. The corrosion resistance was evaluated by scanning electron microscopy on the transition zones between iron and ceramics. Mixtures with increased amount of spinel had higher corrosion resistance and mixtures with fly ash were comparable to mixtures with alumina in terms of corrosion resistance and refractory properties.

Effect of Fly Ash and Slag on the Resistance to H2S Attack of Oil Well Cement

2009 ◽  
Vol 79-82 ◽  
pp. 71-74
Author(s):  
Qi Wang ◽  
Lin Qiao ◽  
Peng Song
Keyword(s):  
Fly Ash ◽  
Compression Strength ◽  
Blended Cement ◽  
Oil Well ◽  
X Ray Diffraction ◽  
X Ray ◽  
Curing Period ◽  
Oil Well Cement ◽  
Xrd Patterns ◽  
Well Cement

In this paper, the resistance to H2S attack of pastes made from slag-fly ash blended cement used in oil well (SFAOW) was studied, in which fly ash (FA) was used at replacement dosages of 30% to 60% by weight of slag. Samples of SCOW and SFAOW pastes were demoulded and cured by immersion in fresh water with 2 Mp H2S insulfflation under 130oC for 15 days. After this curing period, compression strength and permeability of the samples were investigated. The reaction mechanisms of H2S with the paste were carried out through a microstructure study, which included the use of x-ray diffraction (XRD) patterns and scanning electron microscope (SEM). Based on the obtained data in this study, incorporation of FA into SCOW results in the comparable effects in the resistance to H2S attack. When the replacement dosage of slag is about 40%, the paste exhibits the best performance on resistance to H2S attack with compression strength 36.58Mp.

scholarly journals Influence of Mineral Admixtures on Corrosion Inhibition Effect of Nitrites

2018 ◽  
Vol 2018 ◽  
pp. 1-6 ◽  
Author(s):  
Mengna Yang ◽  
Junzhe Liu ◽  
Hui Wang ◽  
Yushun Li ◽  
Yanhua Dai ◽  
...  
Keyword(s):  
Fly Ash ◽  
Corrosion Inhibition ◽  
Ion Concentration ◽  
Mineral Admixtures ◽  
X Ray Diffraction ◽  
Nitrite Ion ◽  
X Ray ◽  
Inhibition Effect ◽  
Diffraction Patterns ◽  
Micro Analysis

Chemical quantitative analysis of effective anticorrosion component and micro-analysis of hydration products of fly ash and slag on the influence of the nitrites corrosion inhibition was studied by the free nitrite ion concentration and X-ray diffraction pattern. The free nitrite ion concentration was used to describe the corrosion inhibition effect of nitrites. And the X-ray diffraction patterns were used to analyze the adsorption properties. The research results show that fly ash and slag were beneficial for improving the corrosion inhibition effect of nitrites. Cement-based materials with slag at low content presented high free nitrite ion concentration, but the addition of low content of fly ash harmed the corrosion inhibition effect of nitrites. The specimens incorporated with both fly ash and slag can reach the highest free nitrite ion concentration when the compounding proportion was 1:1. It was concluded that the extent of mineral admixtures of the corrosion inhibition effect of nitrites was affected by its type and content.

scholarly journals STUDI TENTANG KONDUKTIVITAS DAN RESISTANSI TERMAL GEOPOLIMER BERPORI BERBASIS ABU TERBANG (FLY ASH)

2020 ◽  
Vol 16 (2) ◽  
pp. 161
Author(s):  
Sulfianty Sulfianty ◽  
Nurhayati Nurhayati ◽  
Subaer Subaer
Keyword(s):  
Fly Ash ◽  
X Ray Diffraction ◽  
X Ray

Telah dilakukan penelitian yang bertujuan untuk menyelidiki sifat konduktivitas dan resistansi termalnya. Pembuatan sampel dengan menambahkan agen pembentuk pori (H2O2) ke dalam pasta geopolimer yang diaktivasi menggunakan alkali, dikeringkan (curing) pada suhu 70 ̊C selama 24 jam dan disimpan pada ruang terbuka selama ± 3 hari. Pengujian awal meliputi pengujian porositas, massa jenis dan daya serap air sedangkan pengujian untuk  sampel geopolimer berpori sesuai standar SNI 03-0349-1989 terdiri dari X-ray Diffraction, mikroskop optik digital, konduktivitas dan resistansi termal serta resistansi api dan panas (Shock thermal). Berdasarkan hasil penelitian dapat disimpulkan bahwa penambahan H2O2 akan memperbesar porositas dan daya serap air sehingga massa jenis akan semakin kecil. Sampel yang sesuai standar SNI 03-0349-1989 berdasarkan pengujian awal adalah sampel dengan komposisi 1,6%. Hasil karakterisasi XRD menunjukan bahwa fase berbentuk amorf dengan intensitas tertinggi diperoleh oleh SiO2 dan hasil karakterisasi mikroskop optik digital menunjukan bahwa ukuran pori dari sampel tidak seragam berkisar antara 1-10 mm. Adapun hasil uji konduktivitas dan resistansi termal berturut-turut yaitu 0,77 W/m ̊K dan 0,02 K.m2/W. Serta uji resistansi api dan panas (shock thermal) menunjukan bahwa sampel dapat bertahan hingga 1300 ̊C. Hal ini menunjukan bahwa geopolimer berpori berbahan dasar abu terbang (Fly Ash) memiliki nilai konduktivitas dan resistansi termal yang rendah dan tahan terhadap suhu tinggi sehingga dapat diaplikasikan sebagai bahan isolasi termal yang baik dan ramah lingkungan.

scholarly journals Alkali Fusion-Leaching Method For Comprehensive Processing Of Fly Ash

2017 ◽  
Vol 2 (2) ◽  
pp. 89 ◽  
Author(s):  
A.A. Shoppert ◽  
I.V. Loginova ◽  
L.I. Chaikin ◽  
D.A. Rogozhnikov
Keyword(s):  
Fly Ash ◽  
Power Plant ◽  
X Ray Diffraction ◽  
Water Leaching ◽  
X Ray ◽  
Comprehensive Utilization ◽  
Alkali Fusion ◽  
Wet Chemical ◽  
Promising Source ◽  
Comprehensive Processing

<p>Fly ash, composed of mullite, hematite, amorphous silica and quartz, is a promising source for the recovery of alumina and silica. Desilication with help of NaOH and alkali fusion-leaching method and utilization of alumina and silica in the fly ash for preparation of sodalite and silica white were explored in this research. The samples were characterized by using wet chemical analysis and X-ray diffraction. The optimal extraction of SiO<sub>2</sub> from Reftinskaya power plant fly ash was 46.2% with leaching at 95 <sup>o</sup>C for 3 h. Sodalite was synthesized at 200 °C for 1 h followed water leaching at 95 °C for 1 h. Silica white with specific surface area 180-220 m2/g was prepared by carbonation of the Na<sub>2</sub>SiO<sub>3</sub> solution at 40 <sup>o</sup>C for 90-120 min. The as-prepared silica has a purity of 98,8%.</p><p>The proposed method is suitable for the comprehensive utilization of the fly ash.</p>

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