scholarly journals Use of Isothermal and Isoperibolic Calorimetry to Study the Effect of Zinc on Hydration of Cement Blended with Fly Ash

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5215
Author(s):  
Pavel Šiler ◽  
Iva Kolářová ◽  
Radoslav Novotný ◽  
Jiří Másilko ◽  
Jan Bednárek ◽  
...  
Keyword(s):  
Fly Ash ◽  
Alternative Fuels ◽  
Raw Materials ◽  
Zinc Ions ◽  
X Ray Diffraction ◽  
Induction Periods ◽  
Secondary Raw Materials ◽  
Isoperibolic Calorimetry ◽  
Significant Acceleration ◽  
Poorly Soluble

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. Zinc is one of these elements. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO3)2 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05%, 0.1%, 0.5% and 1% of cement weight. The effect of zinc on hydration was monitored by isothermal and isoperibolic calorimetry. A 15% addition of fly ash to cement mainly causes further retardation of hydration reactions due to the reactions of fly ash particles with Ca2+ ions from cement. The strongest effect on the hydration retardation from all investigated compounds showed in ZnO as it dissolves very slowly. On the contrary, for the dosage of 1% of zinc in the form of ZnCl2 significant acceleration of hydration occurred. In this work, a synergistic effect on the prolongation of hydration with a combination of cement, zinc and fly ash was demonstrated. The lengths of induction periods were assessed from detected calorimetric curves and from these lengths the curves were gained by fitting with the exponential function. Final products were next analyzed using X-ray diffraction.

scholarly journals Possibilities of Use of Isothermal and Isoperibolic Calorimetry to Study the Effect of Zinc on Hydration of Cement Blended with Fly Ash

2020 ◽  
Author(s):  
Pavel Šiler ◽  
Iva Kolářová ◽  
Rdoslav Novotný ◽  
Jiří Másilko ◽  
Jan Bednárek ◽  
...  
Keyword(s):  
Fly Ash ◽  
Alternative Fuels ◽  
Raw Materials ◽  
Alternative Fuel ◽  
Zinc Ions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Secondary Raw Materials ◽  
Isoperibolic Calorimetry ◽  
Poorly Soluble

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. One of elements, the content of which keeps rising in cement is zinc. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO)3 on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05, 0.1, 0.5 a 1% of cement weight. Final products were next analyzed using X-Ray Diffraction.

scholarly journals Application of Isothermal and Isoperibolic Calorimetry to Assess the Effect of Zinc on Hydration of Cement Blended with Slag

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2930 ◽  
Author(s):  
Šiler ◽  
Kolářová ◽  
Novotný ◽  
Másilko ◽  
Bednárek ◽  
...  
Keyword(s):  
Cement Hydration ◽  
Raw Materials ◽  
Isothermal Calorimetry ◽  
Real Life ◽  
Diffraction Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Isoperibolic Calorimetry ◽  
Poorly Soluble ◽  
Furnace Slag

This work deals with the influence of zinc on cement hydration. The amount of zinc in cement has increased over recent years. This is mainly due to the utilization of solid waste and tires, which are widely used as a fuel in a rotary kiln. Zinc can also be introduced to cement through such secondary raw materials as slag, due to increased recycling of galvanized materials. The aim of this work was to determine the effect of zinc on the hydration of Portland cement, blended with ground blast furnace slag (GBFS). This effect was studied by isothermal and isoperibolic calorimetry. Both calorimetry methods are suitable for measurements during the first days of hydration. Isoperibolic calorimetry monitors the hydration process in real-life conditions, while isothermal calorimetry does so at a defined chosen temperature. Zinc was added to the cement in the form of two soluble salts, namely Zn(NO3)2, ZnCl2, and a poorly soluble compound, ZnO. The concentration of added zinc was chosen to be 0.05, 0.1, 0.5, and 1mass percent. The amount of GBFS replacement was 15% of cement dosage. The newly formed hydration products were identified by X-ray diffraction method (XRD).

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.

Porosity Evaluation of Alternative Materials Based on Portland Cement

2014 ◽  
Vol 1000 ◽  
pp. 314-317 ◽  
Author(s):  
Ladislav Pařízek ◽  
Eva Bartoníčková ◽  
Vlastimil Bílek Jr. ◽  
Jiří Kratochvíl
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Coal Combustion ◽  
Mercury Intrusion Porosimetry ◽  
Raw Materials ◽  
High Energy ◽  
Energy Requirements ◽  
Mercury Intrusion ◽  
Secondary Raw Materials ◽  
Alternative Materials

High energy requirements and the resulting economic demands due to the production of Portland cement leads to tendency to replace a portion of cement with secondary raw materials or to use other alternative binders. Among the commonly used cements replacements is currently fly ash which is produced during the coal combustion. In this paper the influence of cement/ash ratio in a paste on paste’s porosity is investigated using mercury intrusion porosimetry.

Silicate Sprayed Mixture Based on Secondary Raw Materials

2019 ◽  
Vol 808 ◽  
pp. 129-135
Author(s):  
Petr Figala ◽  
Rostislav Drochytka ◽  
Radek Hermann ◽  
Jiří Kolísko
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
High Temperature ◽  
Fly Ash ◽  
Raw Materials ◽  
Positive Influence ◽  
Foundry Sand ◽  
Secondary Raw Materials ◽  
Fundamental Research

This paper studies the fundamental research and development of sprayed cement-based mixture designed to withstand the chemically aggressive conditions. The aim of this paper is to verify the possibilities of usage of suitable secondary raw materials as a substitution of a binder and filler of the original mixture while preserving or improving the physical-mechanical properties. In this part of the research was studied the possibility to substitute the binder in rate of 20-60 wt.% by high temperature fly ash and the whole filler by foundry sand and slag. Test samples were made from nine recipes, in which was monitored the influence of secondary raw materials on the compressive strength and the water absorption after 28 days of curing. The results of this paper show, it is possible to successfully substitute part of the binder by high temperature fly ash and the filler wholly by foundry sand in the sprayed mixture. These optimized recipes showed positive influence mainly in the long-term on mechanical properties.

Development of Ultra High Performance Concrete Using Fly Ash

2020 ◽  
Vol 987 ◽  
pp. 33-38
Author(s):  
Rudolf Hela ◽  
Lenka Bodnárová
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Experimental Work ◽  
High Performance ◽  
High Performance Concrete ◽  
Raw Materials ◽  
Economic Cost ◽  
Ultra High Performance Concrete ◽  
Secondary Raw Materials ◽  
Successful Design

The experimental work presented in this article examines the possibility of lowering the economic cost of UHPC. The UHPC were designed using the Linear Packing Density Model. After 7 days, the UHPC compressive strength exceeded 120 MPa. Level of compressive strength after 90 days reaching 150 MPa had been obtained with a lower dose of cement (700 kg/m3) and with the use of secondary raw materials (fly ash), without the use of dispersed reinforcement. The successful design and production proved that the use of secondary raw materials is possible, thereby decreasing the economic cost of UHPC production.

Preparation and Properties of Pressed Metakaolin and Fly Ash Based Alkali-Activated Binders

2014 ◽  
Vol 897 ◽  
pp. 65-68 ◽  
Author(s):  
Jana Boháčová ◽  
Stanislav Staněk ◽  
Pavel Mec
Keyword(s):  
Tensile Strength ◽  
Fly Ash ◽  
High Temperatures ◽  
Frost Resistance ◽  
Raw Materials ◽  
Fly Ashes ◽  
Secondary Raw Materials ◽  
Alkali Activated Binders ◽  
Alkali Activated

Metakaolin, fly ashes and other secondary raw materials serves as suitable input in preparation of alkali-activated binders. This work deals with preparation of alkali-activated materials based on metakaoline and fly ash. Mixtures were prepared with a minimum of mixture water, ready for pressing. Prepared specimens were tested for tensile strength and pressure strength, resistance to high temperatures, frost resistance and resistance to water and salt.

scholarly journals Development of Heterogeneous Alkali Methoxide Catalyst from Fly Ash and Limestone

2020 ◽  
Vol 14 (4) ◽  
pp. 521-530
Author(s):  
W. Widayat ◽  
◽  
Marcelinus Christwardana ◽  
S. Syaiful ◽  
Hantoro Satriadi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Palm Oil ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Raw Materials ◽  
Fatty Acid Content ◽  
Physicochemical Characteristics ◽  
Biodiesel Production ◽  
X Ray Diffraction ◽  
Initial Value

This study is aimed to use fly ash and limestone as raw materials for preparing alkali methoxide heterogeneous catalysts for transesterification of palm oil into biodiesel. The heterogeneous catalyst was synthesized from fly ash and limestone through wet and dry methods and calcined within 1073–1273 K. X-ray diffraction and scanning electron microscopy analyses indicated the well-dispersed presence of the Ca(OCH3)2 crystal over the fly ash and limestone framework, which was mixed using wet method and calcined at 1073 K (W-800). Results showed that W-800 exhibited larger surface area and more uniform active sites than the other catalysts. About 88.6 % of biodiesel was produced from commercial palm oil with W-800 as the catalyst. The product possesses physicochemical characteristics, such as density, kinematic viscosity and free fatty acid content, which satisfy the international biodiesel standard. The catalyst was used for biodiesel production for four cycles, and the biodiesel yield was maintained up to 91.87 % from the initial value.

Experimental Study on High Strength Composite Ceramsite Using Fly Ash and Waste Glass

2013 ◽  
Vol 357-360 ◽  
pp. 1337-1342
Author(s):  
Lei Hong ◽  
Wei Cheng
Keyword(s):  
Experimental Study ◽  
Fly Ash ◽  
Raw Materials ◽  
High Strength ◽  
Waste Glass ◽  
Technological Condition ◽  
Test Results ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

The high strength composite ceramsite was prepared by using fly ash and waste glass as main raw materials and some admixtures such as binder and bubble-forming agent. The suitable technological condition of preparing high strength composite ceramsite was given by studying the influence of the different mix proportions and different sintering systems on the properties of ceramsite. The test results indicate that the compressive strength in cylinder of high strength composite ceramsite which was prepared under certain technological condition can reach 9.9MPa and its bulk density is 974Kg/m3and the water absorption in one hour is 3.6%. The XRD(X Ray Diffraction) and SEM (Scanning Electron Microscope) analyses show that a large number of amorphous gel phases which affect the strength of ceramsite were produced in the process of sintering fly ash and waste glass and abundant even bubbles were formed inside of the ceramsite.

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