Sedimentary Clays as Geopolymer Precursor

2018 ◽  
Vol 39 ◽  
pp. 97-111
Author(s):  
F. Mostefa ◽  
Nasr Eddine Bouhamou ◽  
H.A. Mesbah ◽  
Salima Aggoun ◽  
D. Mekhatria
Keyword(s):  
Sodium Hydroxide ◽  
Mineralogical Composition ◽  
Cementitious Materials ◽  
Raw Material ◽  
X Ray Diffraction ◽  
Calcination Time ◽  
Calorimetric Analysis ◽  
X Ray ◽  
Before And After ◽  
Mechanical Performances

This work aims to study the feasibility of making a geopolymer cement based on dredged sediments, from the Fergoug dam (Algeria) and to evaluate their construction potential particularly interesting in the field of special cementitious materials. These sediments due to their mineralogical composition as aluminosilicates; are materials that can be used after heat treatment. Sedimentary clays were characterized before and after calcination by X-ray diffraction, ATG / ATD, spectroscopy (FTIR) and XRF analysis. The calcination was carried out on the raw material sieved at 80 μm for a temperature of 750 ° C, for 3.4 and 5 hours. The reactivity of the calcined products was measured using isothermal calorimetric analysis (DSC) on pastes prepared by mixing an alkaline solution of sodium hydroxide (NaOH) 8 M in an amount allowing to have a Na / Al ratio close to 1 (1: 1). Also, cubic mortar samples were prepared with a ratio L / S: 0.8, sealed and cured for 24 hours at 60 ° C and then at room temperature until the day they were submited to mechanical testing. to check the extent of geopolymerization. The results obtained allowed to optimize the calcination time of 5 hours for a better reactivity of these sediments, and a concentration of 8M of sodium hydroxide and more suitable to have the best mechanical performances.

scholarly journals Modifying admixtures to cement compositions produced from local raw materials

2018 ◽  
Vol 143 ◽  
pp. 02006
Author(s):  
Daria Vasileva ◽  
Egor Protodiakonov ◽  
Anastasia Egorova ◽  
Svetlana Antsupova
Keyword(s):  
Cement Paste ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Raw Material ◽  
Free Calcium ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Insoluble Compounds

Durability of hardened cement paste depends on chemical and mineralogical composition of Portland cement. The main factor for hardened cement paste is higher content of calcium aluminate and free calcium hydroxide, binding of which into water-insoluble compounds causes increase in resistance to water, frost and corrosion. The purpose of this research is to develop modifying admixtures to cement compositions based on local raw material - rock sand. Chemical and mineralogical properties of the source materials were studied using X-ray spectroscopy and X-ray diffraction analysis. Standard methods were used for defining physico-mechanical properties of sand and binder. Influence of the degree of mechanochemical activation of modifying admixture on the properties of binder and hardened cement paste made on its basis was studied. Research methods of scanning electron microscopy and spectral measurements were applied. The possibility of using admixture based on rock sand as a modifier was determined, its usage providing increase of strength, sulphate and frost resistance, which causes higher durability of cement concrete.

Second-Generation Aluminium Extraction Residue Used as Devitrification Aid for Glass-Ceramics

2008 ◽  
Vol 587-588 ◽  
pp. 773-777
Author(s):  
M.C. Ferreira ◽  
Wilson Acchar ◽  
Ana M. Segadães ◽  
Sonia Regina Homem de Mello-Castanho
Keyword(s):  
Second Generation ◽  
Glass Ceramics ◽  
Glass Frit ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Before And After ◽  
Devitrification Process ◽  
Extraction Metallurgy

Brazil has one of the world’s most important Bauxite deposits, the raw material for the aluminium extraction metallurgy. This work is focused on finding a suitable application for the white dross residue (WDR), a second-generation waste material produced during the metal recovery from the slag left after the primary extraction of aluminium from the ore. A commercial lime-silica based glass frit was used, to which WDR additions were made (up to 30 wt.%), aimed at studying the devitrification process of the glasses produced. Such mixtures were melted at temperatures varying from 1100 to 1500°C and the resulting fritted glasses were heat treated at 900°C. The starting materials and the mixtures thereof were characterized before and after thermal treatment by differential thermal analysis, X-ray diffraction and fluorescence, and scanning electron microscopy. The results obtained showed that the WDR is easily incorporated into the glass matrix and causes easy devitrification after short heat treatment periods at low temperature.

scholarly journals Dynamic hydrothermal synthesis of xonotlite fibers by alkali silica extraction of fly ash

2019 ◽  
Vol 14 ◽  
pp. 155892501989034 ◽  
Author(s):  
Xu Peng
Keyword(s):  
Fly Ash ◽  
Hydrothermal Synthesis ◽  
Coal Fly Ash ◽  
Synthesis Method ◽  
Morphological Characteristics ◽  
Mineralogical Composition ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Silica Material

The silica leached from coal fly ash using alkali, via the hydrothermal method, can be used as the raw material for the synthesis of xonotlite fibers through the hydrothermal synthesis method. This investigation was made to examine how the fly ash desilicated liquid influences the crystal growth and microstructure of xonotlite fibers. The obtained samples were characterized by X-ray diffraction and scanning electron microscope techniques to investigate their mineralogical composition and morphological characteristics. The results indicated that the pure desilication liquid leached from coal fly ash could be used to prepare xonotlite fibers. Xonotlite fibers with single crystal characteristics and large aspect ratio of 100–400 were successfully fabricated from fly ash desilication liquid, which is used as the silica material, at 240°C for 6 h.

The Influence of Mineralogical Composition Changes of Sandstone Cement on Physical-Mechanical Properties

2014 ◽  
Vol 923 ◽  
pp. 71-74
Author(s):  
Kateřina Kovářová ◽  
Zdenek Pala
Keyword(s):  
Mechanical Properties ◽  
Mineralogical Composition ◽  
Winter Period ◽  
Climatic Chamber ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weathering Processes ◽  
Road Salts ◽  
Before And After ◽  
Composition Changes

The aim of the contribution is to present the results of research focused on cement mineralogical composition changes and their influence on physical-mechanical properties of sandstones. Three types of Czech sandstones were tested during this experiment Hořice, Kocběře and Božanov. The sandstone samples were treated in the climatic chamber in order to simulate weathering processes that are typical for winter period in Prague. The influence of road salts was also taken into consideration. For the purposes of mineralogical changes determination the sandstone cement was separated and subsequently analyzed using X-Ray diffraction a DTA/TG analysis. The physical-mechanical properties such as e.g. uniaxial compressive strength, water absorption and open porosity were determined before and after the climatic treatment to enable evaluation of the influence of weathering processes.

Study of Ettringite by Hydration of Yeelimite Clinker

2016 ◽  
Vol 865 ◽  
pp. 126-129
Author(s):  
Radek Magrla ◽  
Karel Dvořák ◽  
Dominik Gazdič ◽  
Marcela Fridrichová
Keyword(s):  
Mineralogical Composition ◽  
Raw Material ◽  
Fluidized Bed Combustion ◽  
X Ray Diffraction ◽  
Laboratory Environment ◽  
X Ray ◽  
Ettringite Formation ◽  
Experimental Works ◽  
Potential Use

This article describes the results of experimental works, dealing with long-term observing of ettringite stability (Ca6Al2(SO4)3(OH)12·26H2O). Thermodynamic stability of this mineral is important in terms of potential use of fluidized bed combustion (FBC) ash as an additive to Portland cement. Within the experimental work it was carried out observing of the ettringite formation by hydration of yeelimitu (Ca4Al6(SO4)·O12) in laboratory conditions. For the preparation of yeelimite it was proposed a three-component raw material mixture, consisting of a high percent limestone and gypsum and corundum. This mixture was subsequently placed in platinum crucibles and burnt in superkanthal kiln at 1200 °C. Formed clinker was mixed in chosen ratio with water and it was prepared a set of testing samples. These samples were exposed in the laboratory environment for up to 180 days. The hydration of the clinker was carried out using X-ray diffraction analysis (XRD) by determining the mineralogical composition.

Modification of Natural Anhydrite by Mixed Exciter

2015 ◽  
Vol 1100 ◽  
pp. 56-59
Author(s):  
Dominik Gazdič ◽  
Jana Stachová ◽  
Radek Magrla
Keyword(s):  
Mineralogical Composition ◽  
Calcium Sulphate ◽  
Sodium Sulphate ◽  
Raw Material ◽  
Technological Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Technical Requirements ◽  
Anhydrous Sodium Sulphate ◽  
Grain Size And Shape

The objective of this experimental work was to monitor the influence of applied external exciter on anhydrite obtained properties. As a basic raw material anhydrite imported from Poland was used, as hydration exciter a mixture of anhydrous sodium sulphate and Portland cement CEM I 42.5 R in total dose of 5 % by anhydrite weight was applied. In the first step the anhydrite underwent the setting of mineralogical composition using the X-ray diffraction analysis (XRD) and monitoring of grain size and shape by the scanning electron microscopy (SEM). In the next step the influence of applied mixing exciter on obtained basic technological properties according to standard CSN EN 13454 was monitored. It was the setting of basic technological properties of anhydrite binder with and without addition of the mixing external exciter and also the setting of strengths of standard anhydrite mortar with addition of external mixing exciter. Upon the obtained values the comparison with technical requirements of the standard for calcium sulphate binders was carried out and this anhydrite mortar was classified as well.

Mineralogy and Microstructural Aspects of Raw and Calcined Sewage Sludge: Considerations for Its Use in Composite Materials

2020 ◽  
Vol 46 (3) ◽  
pp. 384-393
Author(s):  
Maria P.D. Ingunza ◽  
Luis Yermán ◽  
David Williams
Keyword(s):  
Sewage Sludge ◽  
Mineralogical Composition ◽  
Water Source ◽  
Sewage Water ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcination Temperatures ◽  
Treatment Processes ◽  
Mineralogical Phases

Municipal sludge is being increasing considered as a source of raw material in the modern sustainable model policies. This kind of waste exhibits a complex composition mainly due to the sewage water source and the treatment processes. The aim of this work was to study the mineralogy and microstructural aspects of the raw sludge and its mineralogical transformations with calcination in order to obtain a better understanding of its behavior as a raw material in civil construction. Samples of raw sludge and sludge calcined at 700 °C, 800 °C and 900 °C were studied by X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectroscopy. Previously, chemical, thermogravimetric and differential thermal analysis were performed. The results revealed that sewage sludge is a chemically complex material, resulting in a structurally complex mineralogical composition with a strongly contribution of phosphate group. During the calcination, changes appear in the sewage sludge mineralogical phases. Notably, aggregates of Ca-Na-silicon-phosphate can be observed at the highest calcination temperatures.

scholarly journals The Antimicrobial Properties of Modified Pharmaceutical Bentonite with Zinc and Copper

Pharmaceutics ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1190
Author(s):  
Fotini Martsouka ◽  
Konstantinos Papagiannopoulos ◽  
Sophia Hatziantoniou ◽  
Martin Barlog ◽  
Giorgos Lagiopoulos ◽  
...  
Keyword(s):  
Antimicrobial Properties ◽  
Chemical Properties ◽  
Mineralogical Composition ◽  
X Ray Diffraction ◽  
Modified Bentonite ◽  
X Ray ◽  
Before And After ◽  
Antimicrobial Protection ◽  
Main Component ◽  
Phosphate Buffered Saline

Pharmaceutical grade bentonite, containing a high amount of montmorillonite, enriched with zinc (Zn) or copper (Cu) (ZnBent and CuBent, respectively) was used as the main component for the creation of formulations for cutaneous use and tested for their antimicrobial capacity. Bentonite (Bent) with added phenoxyethanol (PH) as a preservative and unmodified bentonite were used as control groups. The mineralogical composition, structural state, and physical or chemical properties, before and after the modification of the samples, were characterized utilizing X-ray Diffraction Analysis (XRD), Fourier-Transform Infrared Spectroscopy (FTIR) and X-ray Fluorescence (XRF) techniques, and Scanning Electron Microscope-Energy Dispersive Spectroscopy (SEM, SEM-EDS) analyses. In addition, the profile of zinc and copper concentration from two types of surfaces ZnBent and CuBent, and into Phosphate-Buffered Saline (PBS) are discussed. Finally, the formulations in the form of basic pastes were challenged against bacteria, molds, and yeasts, and their performance was evaluated based on the European Pharmacopeia criteria. The Cu-modified bentonite performed excellently against bacteria and yeasts, while the Zn-modified bentonite only showed great results against yeasts. Therefore, Cu-modified bentonite formulations could offer antimicrobial protection without the use of preservatives.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

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