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.

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.

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 Autoclaved materials with chalcedonite addition

2018 ◽  
Vol 174 ◽  
pp. 02011 ◽  
Author(s):  
Ryszard Dachowski ◽  
Paulina Kostrzewa ◽  
Sylwia Brelak
Keyword(s):  
Compressive Strength ◽  
Pore Structure ◽  
Bulk Density ◽  
Building Material ◽  
Hydrothermal Conditions ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Ecological Building

Silicate products along with autoclaved aerated concrete are a healthy and ecological building material. Silicates and AAC are the effect of the reaction of the components from which they are formed under hydrothermal conditions. This process is called autoclaving from the name of the devices in which it runs. The tests have shown the effect of the tested additives on the particular properties of autoclaved lime-sand products and lime-sand-cement products. The addition of chalcedonite powder increased both the bulk density and compressive strength of lime-sand products and lime-sand-cement products. Composition modifications contributed to changing the microstructure of the products. In the samples with the addition of chalcedonite powder, fuller tobermorite crystals developed in comparison with the traditional sample. Additives contributed to changes in pore structure and size.

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.

scholarly journals Zeolite Synthesis from Brazilian Coal Fly Ash for Removal of Zn2+ and Cd2+ from Water

2011 ◽  
Vol 356-360 ◽  
pp. 1900-1908 ◽  
Author(s):  
Juliana De Carvalho Izidoro ◽  
Denise Alves Fungaro ◽  
Shao Bin Wang
Keyword(s):  
Fly Ash ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Metal Ion ◽  
Raw Materials ◽  
Coal Fly Ash ◽  
Mineralogical Composition ◽  
Batch Process ◽  
Metal Ion Removal

A Brazilian fly ash sample (CM1) was used to synthesize zeolites by hydrothermal treatment. Products and raw materials were characterized in terms of real density (Helium Pycnometry), specific surface area (BET method), morphological analysis (SEM), chemical composition (XRF) and mineralogical composition (XRD). The zeolites (ZM1) from fly ash were used for metal ion removal from water. Results indicated that hydroxy-sodalite zeolite could be synthesized from fly ash sample. The zeolite presented higher specific surface area and lower SiO2/Al2O3ratio than the ash precursor. The adsorption showed that cadmium is more preferentially adsorbed on ZM1 than zinc. The adsorption equilibrium time for both Zn2+and Cd2+was 20 hours in a batch process. The adsorption isotherms were better fitted by the Langmuir model and the highest percentages of removal using ZM1 were obtained at pH 6 and 5 and doses of 15 and 18 g L-1for Zn2+and Cd2+, respectively. Thermodynamic studies indicated that adsorption of Zn2+and Cd2+by ZM1 was a spontaneous, endothermic process and presented an increase of disorder at the interface solid/solution.

Development of Fly Ash-Based Geopolymer Lightweight Bricks Using Foaming Agent - A Review

2015 ◽  
Vol 660 ◽  
pp. 9-16 ◽  
Author(s):  
Wan Mastura Wan Ibrahim ◽  
Kamarudin Hussin ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Aeslina Abdul Kadir ◽  
Mohammed Binhussain
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Building Material ◽  
Raw Materials ◽  
Construction Materials ◽  
Physical And Mechanical Properties ◽  
Foaming Agent ◽  
Positive Effects ◽  
The World ◽  
Great Development

Bricks are widely used as a construction and building material due to its properties. Recent years have seen a great development in new types of inorganic cementitious binders called ‘‘geopolymeric cement’’ around the world. This prompted its use in bricks, which improves the greenness of ordinary bricks. The development of fly ash-based geopolymer lightweight bricks is relatively new in the field of construction materials. This paper reviews the uses of fly ash as a raw materials and addition of foaming agent to the geopolymeric mixture to produce lightweight bricks. The effects on their physical and mechanical properties have been discussed. Most manufactured bricks with incorporation of foaming agent have shown positive effects by producing lightweight bricks, increased porosity and improved the thermal conductivities of fly ash-based geopolymer bricks. However, less of performances in number of cases in terms of mechanical properties were also demonstrated.

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.

Study on Light Porous Unsintered Building Material

2012 ◽  
Vol 532-533 ◽  
pp. 144-148
Author(s):  
Cong Cong Jiang ◽  
Gou Zhong Li ◽  
Qi Jin Li
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Red Mud ◽  
Building Material ◽  
Building Materials ◽  
Thermal Conductivity Coefficient ◽  
Raw Materials ◽  
Ambient Conditions ◽  
Optimum Ratio ◽  
Broad Application

A light porous unsintered building material was prepared with red mud, fly ash, silica fume as the main raw materials, mixed with a certain amount of foam and curing agent, by the technology of casting and curing at ambient conditions. The influence of different ratio of red mud to fly ash on compressive strength was studied. The microstructure properties of light porous unsintered building material were characterized by scanning electron microscopy (SEM) and then the strength mechanism was studied. The results showed that the optimum ratio of red mud to fly ash was 2:1, and for the best sample, its bulk density was 891kg•m-3, 7d and 28d compressive strength were 8.4MPa and 14.7MPa, thermal conductivity coefficient was 0.235W•(m•K)-1, which may have a broad application prospect in the building materials field.

The Behavior of Fly Ash in Concrete Mixture

2016 ◽  
Vol 714 ◽  
pp. 103-106
Author(s):  
Ondřej Zobal ◽  
Pavel Padevět ◽  
Zdeněk Bittnar ◽  
Lubomír Kopecký ◽  
Vít Šmilauer
Keyword(s):  
Sustainable Development ◽  
Compressive Strength ◽  
Fly Ash ◽  
Raw Materials ◽  
Economic Effect ◽  
Positive Influence ◽  
Concrete Mixture ◽  
The Sustainable Development ◽  
Suitable Material ◽  
Micro Level

It is desirable to use secondary raw materials with regard to the sustainable development. One such suitable material is fly ash. Still enough unused possibility of using fly ash is the use in cement and concrete. This use brings a positive ecological and economic effect. However, it is important to devote to the behavior of fly ash in concrete mixture at the macro and micro level. This paper deals with selected properties as a positive influence on the development of hydration heat, the increase in compressive strength or problems with water absorption fly ash.

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