scholarly journals Effect of Alkali Activator on the Standard Consistency and Setting Times of Fly Ash and GGBS-Based Sustainable Geopolymer Pastes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
M. Dineshkumar ◽  
C. Umarani
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Fluorescence Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkali Activator ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Ft Ir ◽  
Alkaline Activator

In this study, an attempt has been made to study the effect of alkali activator on the standard consistency and setting times of low calcium fly ash (FA) and ground granulated blast furnace slag (GGBS)- based sustainable geopolymer pastes. Different proportions of FA and GGBS were blended into mixes of geopolymer paste using sodium hydroxide (SH) and sodium silicate (SS) as alkaline activator solution (AAS). Tests on geopolymer pastes for consistency and initial and final setting times were carried out for three different SH : SS ratios of 1 : 1, 1 : 2, and 1 : 3 for both 2.5 M (molarity) and 5.0 M of SH concentration. While increasing the molarity of SH, both consistency and setting time decreased. For all the blended binder mix, the setting time decreases with an increase in the quantity of SS in the alkali activator solution. An increase in the amount of GGBS content in the geopolymer blended binder mix increases the consistency and decreases the setting time. For both 2.5 M and 5 M blended geopolymer mixes, a decrease in the percentage of GGBS and an increase in the percentage of FA increased the setting time. Microstructural studies such as X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out, and the results are presented. The FT-IR spectra for the blended binder mixes demonstrated the formation of geopolymerization and the presence of the functional groups.

scholarly journals The Role of Mineral Matter in Concentrating Uranium and Thorium in Coal and Combustion Residues from Power Plants in Poland

Minerals ◽  
2019 ◽  
Vol 9 (5) ◽  
pp. 312 ◽  
Author(s):  
Henryk R. Parzentny ◽  
Leokadia Róg
Keyword(s):  
Fly Ash ◽  
Power Plants ◽  
Fluorescence Analysis ◽  
Atomic Emission ◽  
Mineral Matter ◽  
X Ray Diffraction ◽  
X Ray ◽  
Waste Storage ◽  
Upper Silesian Coal Basin

Based on the results of tests on feed coal from the Lublin Coal and Upper Silesian Coal Basin and its fly ash and slag carried out using X-ray diffraction and X-ray fluorescence analysis, atomic emission spectroscopy, and scanning electron microscopy, it was found that in feeds, coal Th is associated with phosphates and U with mineral matter. The highest Th content was found in anhedral grains of monazite and in Al-Si porous particles of fly ash of <0.05 mm size; whereas in the slag, Th is concentrated in the massive Al-Si grains and in ferrospheres. U is mainly concentrated in the Al-Si surface of porous grains, which form a part of fly ash of <0.05 mm size. In the slag, U is to be found in the Al-Si massive grains or in a dispersed form in non-magnetic and magnetic grains. Groups of mineral phase particles have been identified that have the greatest impact on the content of Th and U in whole fly ash and slag. The research results contained in this article may be important for predicting the efficiency of Th and U leaching from furnace waste storage sites and from falling dusts to soils and waters.

scholarly journals Mechanical and Microstructural Properties of Copper Slag Based Blended Geopolymer Concrete

2021 ◽  
Author(s):  
Vijayasarathy RATHANASALAM ◽  
Jayabalan PERUMALSAMI ◽  
Karthikeyan JAYAKUMAR
Keyword(s):  
Fly Ash ◽  
Mechanical Characterization ◽  
Copper Slag ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulated Blast Furnace Slag ◽  
Mechanical And Microstructural Properties ◽  
Furnace Slag

This work presents a novel way to examine the characteristics of fly ash, copper slag (CPS) along with the addition of Ultrafine Ground Granulated Blast Furnace Slag (UFGGBFS) based Geopolymer Concrete (GPC) for various molarities (10M, 12M and 14M). In GPC, fly ash was replaced with UFGGBFS (5 %, 10 % and 15 %) and copper slag was used as fine aggregate. Mechanical Characterization such as split tensile, flexural strength, workability and water absorption were conducted . GPC characterization and microstructural behaviour was studied  by examining X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). From experimental results this study concludes that with a rise in molarity of GPC, along with incorporation of UFGGBFS, improved the performance, densification and strength of GPC.

scholarly journals Metakaolin-Based Geopolymer with Added TiO2 Particles: Physicomechanical Characteristics

Coatings ◽  
2017 ◽  
Vol 7 (12) ◽  
pp. 233 ◽  
Author(s):  
Luis Guzmán-Aponte ◽  
Ruby Mejía de Gutiérrez ◽  
Anibal Maury-Ramírez
Keyword(s):  
Cement Content ◽  
Setting Time ◽  
Physicomechanical Properties ◽  
X Ray Diffraction ◽  
Microstructural Characteristics ◽  
X Ray ◽  
Physicomechanical Characteristics ◽  
Tio2 Particles ◽  
Setting Times ◽  
Tio2 Addition

The effect of the TiO2 addition on the physicomechanical properties of a geopolymer system based on metakaolin (MK) and hydroxide and potassium silicate as activators is presented in this article. Three different liquid-solid systems (0.35, 0.40, and 0.45) and two titanium additions were investigated (5% and 10% of the cement content). The flowability, setting time, and mechanical strength of the geopolymer mixtures and their microstructural characteristics were evaluated using techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). It was concluded that a percentage of up to 10% TiO2 does not affect the mechanical properties of the geopolymer, although it does reduce the fluidity and setting times of the mixture.

The Effect of Fly Ash on TSA of Cementitous Material: Based on Three Years Results

2013 ◽  
Vol 539 ◽  
pp. 139-144
Author(s):  
Ben Wan Liu ◽  
Chang Hui Yang ◽  
Xiao Bin Xiang ◽  
Lin Wen Yu ◽  
Jing Zhang
Keyword(s):  
Fly Ash ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Ft Ir ◽  
Secondary Hydration

The thaumasite form of sulfate attack of cementitous material (TSA) is a new kind of sulfate attack and it is more harmful than traditional sulfate attack. By means of Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), the effect of dosage and fineness of fly ash on TSA of cementitous material were investigated in this paper. The specimens had been immersed in magnesium sulfate solution of 5% mass concentration at 5±2° C for three years. The results showed that fly ash could not restrain the formation of thaumasite but it delayed the occurrence of TSA in cementitous material when 30% fly ash takes place of cement. Fly ash could enhance the resistance of cementitous material to TSA through secondary hydration reaction to optimizing the pore structure of hardened cement paste and lowering the C/S of C-S-H gel.

scholarly journals Investigation on the Compressive Strength and Time of Setting of Low-Calcium Fly Ash Geopolymer Paste Using Response Surface Methodology

Polymers ◽  
2021 ◽  
Vol 13 (20) ◽  
pp. 3461
Author(s):  
Pauline Rose J. Quiatchon ◽  
Ithan Jessemar Rebato Dollente ◽  
Anabel Balderama Abulencia ◽  
Roneh Glenn De Guzman Libre ◽  
Ma. Beatrice Diño Villoria ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Unconfined Compressive Strength ◽  
Setting Time ◽  
Initial Setting Time ◽  
Alkali Activator ◽  
Setting Times ◽  
Confirmatory Tests ◽  
Initial Setting

Approximately 2.78 Mt of coal fly ash is produced in the Philippines, with a low utilization rate. Using fly ash-based geopolymer for construction will lessen the load sent to landfills and will result in lower GHG emissions compared to OPC. It is necessary to characterize the fly ash and optimize the geopolymer components to determine if it can replace OPC for in situ applications. The activator-to-precursor ratio, the water-to-solids ratio, and the sodium hydroxide-to-sodium silicate ratio were optimized using a randomized I-optimal design from the experimental results of 21 runs with five replicates, for a total of 105 specimens of 50 mm × 50 mm × 50 mm paste cubes. The engineering properties chosen as the optimization responses were the unconfined compressive strength (UCS), the initial setting time, and the final setting time. The samples were also ambient-cured with the outdoor temperature ranging from 30 °C to 35 °C and relative humidity of 50% ± 10% to simulate the on-site environment. Runs with high unconfined compressive strength (UCS) and short setting times were observed to have a low water-to-solids (W/S) ratio. All runs with a UCS greater than 20 MPa had a W/S ratio of 0.2, and the runs with the lowest UCS had a W/S of 0.4. The initial setting time for design mixes with a W/S ratio of 0.2 ranged from 8 to 105 min. Meanwhile, five out of seven design mixes with a W/S ratio of 0.4 took longer than 1440 min to set. Specimens with an alkali activator ratio (NaOH/WG) of 0.5 (1:2) and 0.4 (1:2.5) also had significantly lower setting times than those with an alkali activator ratio of 1. The RSM model was verified through confirmatory tests. The results of the confirmatory tests are agreeable, with deviations from the expected UCS ranging from 0 to 38.12%. The generated model is a reliable reference to estimate the UCS and setting time of low-calcium FA geopolymer paste for in situ applications.

scholarly journals Early-age Properties of High-volume Fly Ash Concrete Mixes for Pavement: Volume 2

2021 ◽  
Author(s):  
Aniruddha Baral ◽  
◽  
Jeffery Roesler ◽  
Junryu Fu ◽  
◽  
...  
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
High Volume ◽  
Early Age ◽  
X Ray ◽  
Fly Ash Concrete ◽  
Setting Times ◽  
Chemical Admixtures ◽  
High Volume Fly Ash ◽  
Foam Index

High-volume fly ash concrete (HVFAC) is more cost-efficient, sustainable, and durable than conventional concrete. This report presents a state-of-the-art review of HVFAC properties and different fly ash characterization methods. The main challenges identified for HVFAC for pavements are its early-age properties such as air entrainment, setting time, and strength gain, which are the focus of this research. Five fly ash sources in Illinois have been repeatedly characterized through x-ray diffraction, x-ray fluorescence, and laser diffraction over time. The fly ash oxide compositions from the same source but different quarterly samples were overall consistent with most variations observed in SO3 and MgO content. The minerals present in various fly ash sources were similar over multiple quarters, with the mineral content varying. The types of carbon present in the fly ash were also characterized through x-ray photoelectron spectroscopy, loss on ignition, and foam index tests. A new computer vision–based digital foam index test was developed to automatically capture and quantify a video of the foam layer for better operator and laboratory reliability. The heat of hydration and setting times of HVFAC mixes for different cement and fly ash sources as well as chemical admixtures were investigated using an isothermal calorimeter. Class C HVFAC mixes had a higher sulfate imbalance than Class F mixes. The addition of chemical admixtures (both PCE- and lignosulfonate-based) delayed the hydration, with the delay higher for the PCE-based admixture. Both micro- and nano-limestone replacement were successful in accelerating the setting times, with nano-limestone being more effective than micro-limestone. A field test section constructed of HVFAC showed the feasibility and importance of using the noncontact ultrasound device to measure the final setting time as well as determine the saw-cutting time. Moreover, field implementation of the maturity method based on wireless thermal sensors demonstrated its viability for early opening strength, and only a few sensors with pavement depth are needed to estimate the field maturity.

Preparation and Characterization of Fibri-Form Silica from Short Chrysotile Fibers by Mix-Roasting

2014 ◽  
Vol 809-810 ◽  
pp. 313-318
Author(s):  
Peng Cheng Song ◽  
Tong Jiang Peng ◽  
Hong Juan Sun ◽  
Yu Cao Yu
Keyword(s):  
Electron Microscopy ◽  
Thermal Analysis ◽  
Scanning Electron Microscopy ◽  
Fluorescence Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Fibrous Morphology ◽  
Ft Ir ◽  
Scanning Electron

Fibri-form silica was extracted from short chrysotile fibers by mix-roasting with ammonium bisulfate. The fibri-form silica were characterized by X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N2 adsorption isotherms. The results show that the fibri-form silica with disordered crystalline structure, but also in fibrous morphology. The surface area and pore volume of fibri-form silica are 181.66 m2/ g and 0.44 cc/ g, respectively. The structure of fibri-form silica is stable, no phase transformed from 50 to 1200 oC.

scholarly journals SINTESIS DAN KARAKTERISASI ZEOLIT FAUJASIT DARI LIMBAH BATUBARA OMBILIN DENGAN METODA ALKALI HIDROTERMAL AIR LAUT

2016 ◽  
Vol 8 (2) ◽  
pp. 165
Author(s):  
Upita Septiani ◽  
Widya Yuliani Fatiha ◽  
Syukri Arief
Keyword(s):  
Fly Ash ◽  
Sea Water ◽  
Coal Fly Ash ◽  
Hydrothermal Process ◽  
Zeolite Synthesis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hydrothermal Processes ◽  
Infra Red ◽  
Ft Ir

Zeolite synthesis using Ombilin coal fly ash at low temperature with alkaline hydrothermal process has been carried out. The used Fly ash was melted by NaOH at a temperature of 550°C. Alkaline hydrothermal processes in zeolite synthesis performed with variations of temperature at 35°C , 45°C and 60°C . The zeolite that obtained was characterized by using Fourier Transform Infra Red (FT - IR), X - Ray Diffraction (XRD) , Scanning Electron Microscopy (SEM) in combination with EDX . The characterization results showed the formation of zeolite were better when an increasing in temperature processes and the use of sea water as a solvent. On the use of seawater, were obtained sodalit zeolite with the chemical formula Na8(Al6Si6O24)Cl2.

Structural Features of Fibri-Form Silica from Short Chrysotile Fibers by Acid-Leaching

2015 ◽  
Vol 814 ◽  
pp. 199-206
Author(s):  
Peng Cheng Song ◽  
Tong Jiang Peng ◽  
Hong Juan Sun ◽  
Yu Cao Yu ◽  
Hai Yang Xian
Keyword(s):  
Acid Leaching ◽  
Fluorescence Analysis ◽  
Average Diameter ◽  
Structural Features ◽  
Inorganic Acid ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Ft Ir ◽  
20 Nm

The fibri-form silica was successfully synthesized from the short chrysotile fibers by inorganic acid-leaching. X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), thermogravimetry and differential thermal analysis (TG-DTA), scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR) and N2adsorption isotherms were used to characterize the products. The results indicate that the fibri-form silica is a kind of noncrystalline material, and the content of SiO2in the fibri-form silica is 98.30%. From 50°C to 1200°C, the structure of fibri-form silica is stable. The average diameter of single fiber range from 20 nm to 50nm and the lengths are 50nm to 3μm. The surface area and pore volume of fibri-form silica are 369.22m2/g and 0.43cc/g, respectively. And the size of pore diameters are different, is one of mesopore materials presenting high quality filler and catalyzer carrier.

Utilization of Modified Coal Fly Ash (CFA) as a Catalyst for Production of Biodiesel from Coconut Oil: Part 1 - Characteristics of the Catalyst

2020 ◽  
Vol 981 ◽  
pp. 190-195
Author(s):  
Arif Hidayat ◽  
Achmad Chafidz ◽  
Bachrun Sutrisno
Keyword(s):  
Fly Ash ◽  
Surface Area ◽  
Coal Fly Ash ◽  
Coconut Oil ◽  
Biodiesel Production ◽  
X Ray Diffraction ◽  
Average Pore ◽  
Xrd Pattern ◽  
X Ray ◽  
Ft Ir

The current research studied about the utilization of modified coal fly ash (CFA) as catalyst for biodiesel production from coconut oil. Coal Fly ash (CFA) is a solid waste that is abundantly available in the coal-based power plant. Coal Fly Ash is a type of material that has high content of oxide minerals, e.g. silicates and silicate alumina. With proper physical/chemical treatment, the coal fly ash can be converted into a heterogeneous catalyst. In this work, the coal fly ash was modified with HCl and Ca(NO3)2·4H2O and used as catalyst for biodiesel production from coconut oil. This paper will focus only on the characteristics of the prepared modified CFA-based catalyst. The modified CFA-based catalyst was characterized for its crystallinity using X-Ray Diffraction (XRD), determined its surface area and pore size distribution using Surface Area Analyzer, and its functional groups by Fourier Transform – Infra Red (FT-IR). The specific surface area of the catalyst (modified CFA) decreased from 28.08 m2/g to 17.54 m2/g after impregnation process of calcium oxide in the raw coal fly ash. This decrease was also accompanied by a decrease in the average pore network from 32.59 Å to 20.31 Å. Additionally, based on the XRD pattern shown, the raw CFA is composed of mostly quartz (SiO2) and mullite (3Al2O3.2SiO2) minerals, and a small portion of hematite.

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