Hydrothermal Synthesis of Tobermorite at 170 and 190 °C from Fly Ash and Quartz Sand

2016 ◽  
Vol 865 ◽  
pp. 42-46 ◽  
Author(s):  
Ján Fleischhacker ◽  
Ester Helanová ◽  
Rostislav Drochytka
Keyword(s):  
Fly Ash ◽  
Hydrothermal Synthesis ◽  
Quartz Sand ◽  
Raw Materials ◽  
Molar Ratio ◽  
Hydrothermal Conditions ◽  
Temperature Combustion ◽  
Concrete Mechanical Properties ◽  
Aerated Concrete ◽  
High Temperature Combustion

Tobermorite is the main mineral which provides to aerated concrete mechanical properties. It is produces during hydrothermal conditions by reacting silicon and calcium oxides. Within this research was evaluated tobermorite formation using high temperature combustion fly ash and quartz sand, as the siliceous raw materials. As a binder was used lime. Emphasis was also placed on the molar ratio of C/S, which is crucial for the formation of tobermorite and was given 0.73 and 1.00. Hydrothermal synthesis was carried out in a laboratory autoclave at temperatures of 170 and 190 °C.

The Influence of Sulfates on Tobermorite Formation in Lime-Ash Composite

2018 ◽  
Vol 916 ◽  
pp. 179-183
Author(s):  
Vit Cerný ◽  
Jindrich Melichar ◽  
Jan Fleischhacker ◽  
Rostislav Drochytka
Keyword(s):  
Fly Ash ◽  
Hydrothermal Synthesis ◽  
Building Material ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Positive Influence ◽  
Hydrothermal Conditions ◽  
Long Time ◽  
Aerated Concrete ◽  
Ecological Building

Autoclaved aerated concrete is an ecological building material with suitable properties and long-time tradition. The research of secondary raw materials usage and technology optimization is needed in order to increase the efficiency and sustainability of its production. It is important to focus on development of mineralogical composition while studying the influence of input materials and the parameters of hydrothermal synthesis on the properties of final product. This is especially important in case of tobermorite formation as the bearer of strength in the structure. Main focus of this paper is applicability of fly ash (silica component) and admixture of energo-gypsum (sulfate component) in production of lime-ash composite in hydrothermal conditions. The research was focused on autoclaving of samples at temperature of 170°C in three various isothermal sustains. Final samples were analyzed by XRD and SEM in order to proof the influence of input materials. Results show that 5% admixture of energo-gypsum had positive influence on tobermorite formation.

The Use of Anthracite Fly Ash for the Production of Autoclaved Aerated Concrete

2012 ◽  
Vol 512-515 ◽  
pp. 3003-3006
Author(s):  
Rostislav Drochytka ◽  
Vit Cerný ◽  
Karel Kulísek
Keyword(s):  
Heat Treatment ◽  
Fly Ash ◽  
Construction Industry ◽  
Raw Materials ◽  
Exothermic Reaction ◽  
Reaction Heat ◽  
Anthracite Coal ◽  
Concrete Production ◽  
Aerated Concrete ◽  
Cellular Concrete

Burning high-quality anthracite coal produces ash with a high content of unburned residues, which in many cases permanently exceeds 20%. These ashes usually contain high levels of amorphous phase providing the pozzolanic activity, this making them particularly useful if potentially applied in the construction industry. Such potential of effective treatment necessitates reducing the content of unburned residues, the best level here being less than 4% w/w. This paper deals with the results of testing heat treatment of fly ashes particularly using the resources of eastern Slovakia. Tests have shown that tested process of heat treatment can safely reduce the content of unburned residues in fly ash whilst maintaining high levels of the glass phase. Raw materials thus modified meet the requirements for the use in cellular concrete production technology with beneficial use of exothermic reaction heat from fly ash treatment in pre-heating the autoclaves.

Synthesis Method and its Influence Factors of Hydrotalcite-Like Compounds

2013 ◽  
Vol 690-693 ◽  
pp. 351-354 ◽  
Author(s):  
Hong Dan Xue ◽  
Fu Li Wang ◽  
Guo Li Li ◽  
Pu Liu ◽  
Yong Qing Bai ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Reduction Method ◽  
Ph Value ◽  
Raw Materials ◽  
Sol Gel ◽  
Synthesis Method ◽  
Influence Factors ◽  
Synthetic Methods ◽  
Molar Ratio ◽  
Temperature Reaction

Hydrotalcite-like compounds are a class of anionic lays or layed double hydroxiods (LDHs) which consists of alkalescence, anion-exchanges and memory effect. The synthetic methods of LDHs include coprecipitation, hydrothermal synthesis, mirowave radiation, ion exchange, sol-gel method, roasting reduction method, instant synthesis, etc.The molar ratio of raw materials, pH value,reaction temperature,reaction time and so on have a greater impact on the purity and crystallinity of the LDHs.

Content of Aluminium Hydroxide in Lime-Silica Composite and its Influence on Tobermorite Formation

2018 ◽  
Vol 916 ◽  
pp. 195-199 ◽  
Author(s):  
Jindrich Melichar ◽  
Vit Cerný ◽  
Jan Fleischhacker ◽  
Rostislav Drochytka
Keyword(s):  
Mechanical Properties ◽  
Aluminium Hydroxide ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Silica Sand ◽  
Chemical Formula ◽  
Hydrothermal Conditions ◽  
Silicon Oxides ◽  
Calcium Hydrosilicates ◽  
Aerated Concrete

Aerated concrete is lightweight building material with excellent thermos-technical properties compared to its strengths, easy workability and economic efficiency. It is material with long tradition of manufacturing since 1924 but its potential is yet possible to be extended. Since the beginning pure ingredients such as lime and silica sand has been used. Nowadays we are looking for ways to replace these expensive raw materials with cheaper alternatives. One of the most important mechanical properties of each material is its strength. In case of aerated concrete the bearer of strength is mineral tobermorite. It is created by reaction of silicon oxides and lime at hydrothermal conditions. It belongs to the group of calcium hydrosilicates with chemical formula Ca5Si6O16(OH)2·4H2O. Main goal of this paper is proposal for modification of the raw materials composition and autoclave regime of aerated concrete using aluminium hydroxide in order to improve final mechanical properties and mineralogical composition.

scholarly journals Utilization of Construction and Demolition Waste, Fly Ash Waste in Autoclaved Aerated Concrete

2020 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Fly Ash ◽  
Aluminum Powder ◽  
Power Plants ◽  
Raw Materials ◽  
Thermal Power ◽  
Construction And Demolition Waste ◽  
Construction Sector ◽  
Demolition Waste ◽  
Concrete Material ◽  
Aerated Concrete

China's industries are rapidly growing, and with that generation of waste is also increasing. Associated environmental concerns over construction and demolition waste, industrial waste such as fly ash generated by thermal power plants need to be utilized in some form. Autoclave aerated concrete is a lightweight material that can be used as an alternative building material; it is widely composed of raw materials such as cement, quicklime, sand, gypsum, and an aerating agent like aluminum powder. In this study, 40% waste will be utilized, Construction waste (5%,10%,15%....40%) and Fly ash (35%,30%,25….0%)respectively, keeping the aerating agent constant at 0.06% that is aluminum powder. The compressive strength of the material will be checked after autoclaving at 2000 temperature and 1Mpa Pressure for 6 hours. The study aims to design an autoclave aerated concrete material and to recycle the waste generated by various industries mainly from the construction sector.

scholarly journals Effect of modifiers and mineral additives from industrial waste on the quality of aerated concrete products

Technobius ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 0010
Author(s):  
Yerlan Sabitov ◽  
Duman Dyussembinov ◽  
Daniyar Bazarbayev
Keyword(s):  
Fly Ash ◽  
Polyvinyl Acetate ◽  
Raw Materials ◽  
Capillary Suction ◽  
Pulsation Apparatus ◽  
Rotary Pulsation Apparatus ◽  
Aerated Concrete ◽  
The Given ◽  
Mineral Additives

The given article is devoted to research of influence of polymer modifiers and mineral additives on quality of composite aerated concrete products. When selecting the composition of composite aerated concrete local raw materials and components were used: portland cement, sand, aluminum powder, polyvinyl acetate, fly ash, post-alcoholic bard and whey of milk. Preliminary polyvinyl acetate was combined with binder mixing water at a temperature above 55ºC to obtain a readily soluble polymer emulsion. Dispersion was carried out with a rotary-pulsation apparatus at a pressure of 0.5-1.0 MPa and a rotor speed of ~1200 rpm. In the same apparatus the complex modifier was produced. The offered technology of production of a complex modifier seems to be the most effective for composite aerated concrete. It made it possible to reduce water absorption and capillary suction of composite aerated concrete by an average of 25% and 45%, respectively. Moreover, different combinations of fly ash, polymer and modifier made it possible to achieve optimal values of thermal conductivity, compressive strength and frost resistance of composite aerated concrete.

Hydrothermal Synthesis and Characterization of LiZr2(PO4)3

2012 ◽  
Vol 512-515 ◽  
pp. 195-198
Author(s):  
Jin Ye Niu ◽  
Zhi Wei Chen ◽  
Cheng Gong Sun ◽  
Liu Feng ◽  
Zheng Min Li ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Ph Value ◽  
Solid Phase ◽  
Low Cost ◽  
Reaction System ◽  
Xrd Analysis ◽  
Molar Ratio ◽  
Solid Phase Reaction ◽  
Phase Reaction ◽  
Hydrothermal Conditions

Lithium dizirconium phosphate (LiZr2(PO4)3) possesses good ionic conductivity owing to its unique framework structure and can be used as favorable anode material in Li-ion battery. LiZr2(PO4)3 is commonly prepared by solid phase reaction in which higher temperature is needed and pure LiZr2(PO4)3 without other phases is difficult to obtain in the final products. In this paper, low cost hydrothermal synthesis of pure (LiZr2(PO4)3) was studied. Effects of the hydrothermal conditions (molar ratios of Li+ to ZrOCl2, addition of HF, pH values of reaction system and hydrothermal temperatures) on the phase composition of the products were investigated. The results showed that pure LiZr2(PO4)3 was successfully prepared at lower temperature of 80°C for 24h with the addition of HF when the pH value was adjusted to 5.0 and the molar ratio of Li+ to ZrOCl2 was 0.5 with the concentration of ZrOCl2 as 0.6mol/L. The phases and purity of the final products were characterized by XRD analysis.

Use of Fluidized Bed Combustion Fly Ash as Addition Reducing Shrinkage of Concrete

2016 ◽  
Vol 865 ◽  
pp. 141-144 ◽  
Author(s):  
Lucia Osuská ◽  
Rudolf Hela
Keyword(s):  
Composite Material ◽  
High Temperature ◽  
Fly Ash ◽  
Fluidized Bed ◽  
Fresh Concrete ◽  
Fluidized Bed Combustion ◽  
Free Lime ◽  
Natural Properties ◽  
Temperature Combustion ◽  
High Temperature Combustion

Volumetric changes during ageing belong to natural properties of concrete. These changes, either growing or shrinking, can present a problem, which has to be taken into account during design and realization phases. This phenomenon is influenced by various factors and volumetric changes can be eliminated in many ways. One of the possibilities is setting appropriate combination of input materials and use of special additions and admixtures. This paper focused on verification of the method reducing shrinkage of concrete by means of using high temperature combustion fly ash combined with fluidized bed combustion fly ash as addition. The precondition is growth of new forms, in particular primary ettringite and monosulphate, which form because of the content free lime and sulphates in fluidized fly ash. If these minerals are formed in fresh concrete, they can positive prevent shrinkage without destruction of the composite material.

Effect of Raw Material Ratios on the Compressive Strength of Chang Jiang Iron Ore Gangues Aerated Concrete Block

2012 ◽  
Vol 573-574 ◽  
pp. 92-98
Author(s):  
Wen Hua Xu ◽  
Hao Zhang ◽  
Wei Jun Ren ◽  
Jin Yi Wu
Keyword(s):  
Compressive Strength ◽  
Aluminum Powder ◽  
Quartz Sand ◽  
Iron Ore ◽  
Raw Materials ◽  
Dry Weight ◽  
Concrete Block ◽  
Raw Material ◽  
Optimum Ratio ◽  
Aerated Concrete

The present study was to investigate the production of aerated concrete block from ChangJiang iron ore gangues. Analyze Quartz Sand, cement, CaO and gangue’s ratio’s influence on the aerated concrete block’s compressive strength, and then determine the optimum ratio. The results shows that gangue, quartz sand, cement, CaO, gypsum, aluminum powder, additive’s optimum ratio is 60.11%，8.26%，15.03%, 14.07%, 2%, 0.06% and 0.07% the dry weight of raw materials. Obtain the strongest compressive strength with the ratio 0.59:1 for water and raw materials. Adding iron gangues into aerated concrete block can turn wastes into treasures, which is originally done by us.

Development of Structural Concrete with Fly Ash

2014 ◽  
Vol 1054 ◽  
pp. 143-147 ◽  
Author(s):  
Rudolf Hela ◽  
Martin Ťažký
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Power Plants ◽  
Elasticity Modulus ◽  
Partial Replacement ◽  
Past Century ◽  
The Past ◽  
Temperature Combustion ◽  
Pozzolanic Properties ◽  
High Temperature Combustion

The paper describes problems of using fly ash in concrete. Using fly ash produced during high temperature combustion in power plants as addition for concrete has been known since the 60s of the past century. The Standard EN 206 Concrete - Specification, performance, production and conformity characterizes high temperature combustion fly ash as an addition of the type II, i.e. active addition with pozzolanic properties. Use of fly ash as an active addition also enables partial replacement of cement. The paper solves the extent of cement which can be replaced with fly ash in this manner. Influence of addition of fly ash on consistency of concrete, development of compressive strength and elasticity modulus at the age of 7, 28, 60 and 90 days of concrete are observed.

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