scholarly journals Alkali-Activated Metakaolin and Fly Ash as Unfired Ceramic Bonding Systems

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 197
Author(s):  
Jozef Vlček ◽  
Michaela Topinková ◽  
Miroslava Klárová ◽  
Petra Maierová ◽  
Hana Ovčačíková ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Water Glass ◽  
Raw Materials ◽  
Alkali Activation ◽  
Activation Process ◽  
Laboratory Conditions ◽  
Naoh Solution ◽  
Bonding Systems

Metakaolin (MK) prepared by the calcination of kaolin at 550 °C and fly ash (FA) from the combustion of black coal in a granulating boiler were used to prepare unfired ceramic bonding systems via the alkali activation process. A long-term stability of the mechanical properties of the prepared samples similar to the unfired ceramic systems was observed. The optimal metakaolin and fly ash ratio, the type of the activator (NaOH or water glass) and its concentration were evaluated after the hydration in: a) laboratory conditions; b) hydration box; and c) under the hydrothermal activation. Raw materials and the samples prepared by alkali activation process were characterized by XRD, XRF, TG/DTA, and FTIR methods. The mechanical properties of the prepared samples were tested using a compressive strength test after 2, 28 and 56 days of hydration. The compressive strengths of 16 and 24 MPa after 28 days of hydration were reached for FA samples activated with water glass. The alkali activation of MK was successful in the NaOH solution of the molar concentration above 5 M. The compressive strength values of metakaolin, activated hydrothermally and hydrated at laboratory conditions, reached 11.2 and 5.5 MPa, respectively, for 5 M activator of NaOH.

Use of Water Glass from Rice Husk and Bagasse Ashes in the Preparation of Fly Ash Based Geopolymer

2019 ◽  
Vol 798 ◽  
pp. 364-369 ◽  
Author(s):  
Khemmakorn Gomonsirisuk ◽  
Parjaree Thavorniti
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Rice Husk ◽  
Ball Mill ◽  
Water Glass ◽  
Rice Husk Ash ◽  
Raw Materials ◽  
Agricultural Waste ◽  
Preparation Process

The aim of this work is to study the feasibility of preparation of fly ash based geopolymer using sodium water glass from agricultural waste as alternative activators. Rice husk ash and bagasse ash were used as raw materials for producing sodium water glass solution. The sodium water glass were produced by mixing rice husk ash and bagasse ash with NaOH in ball mill and boiling. The prepared sodium water glass were analyzed and used in geopolymer preparation process. The geopolymer paste were prepared by adding the obtained water glass and NaOH with fly ash. After cured at ambient temperature for 7 days, mechanical properties were investigated. Bonding and phases of the geopolymer were also characterized. The geopolymer from rice husk ash presented highest compressive strength about 23 MPa while the greatest for bagasse ash was about 16 MPa.

scholarly journals Comparison of mechanical properties of geopolymers from different raw materials with the addition of waste glass

2021 ◽  
pp. 252-261
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Fossil Fuels ◽  
Raw Materials ◽  
Waste Glass ◽  
Industrial Wastes ◽  
Raw Material ◽  
Sustainable Construction ◽  
Alkali Activation ◽  
Compressive And Flexural Strengths

The combustion of fossil fuels results in creating a lot of solid wastes such as fly ash and slag. However, these environmentally unfriendly materials can be used as a raw material for alkali activation – geopolymerization. Although these wastes have been successfully used in industrial production for several decades, its use does not achieve the level of its potential. Today, to achieve a sustainable construction industry, alternative cement has been extensively investigated. Geopolymer (GP) is a kind of material that is obtained from the alkaline activator, and it can be produced from industrial wastes or by-products. The aim of this work was to describe the improvement of mechanical properties of alkali-activated binders – geopolymers made of fly ash and blast furnace slag. The effect of the addition of waste glass in three different values feed into fly ash or GGBFS, and its impact on mechanical properties (compressive and flexural strengths) of geopolymers was examined. The highest value of compressive strength was achieved with 20% waste glass addition to a fly ash sample on 90th day 58,9 MPa. The waste glass was added in the form of broken and crushed glass particles.

scholarly journals Effect of Ordinary Portland Cement and Water Glass on the Properties of Alkali Activated Fly Ash Concrete

Minerals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 40 ◽  
Author(s):  
Vytautas Bocullo ◽  
Danutė Vaičiukynienė ◽  
Ramūnas Gečys ◽  
Mindaugas Daukšys
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Portland Cement ◽  
Water Glass ◽  
Ordinary Portland Cement ◽  
Reference Sample ◽  
Freeze And Thaw ◽  
Naoh Solution ◽  
Increased Strength ◽  
Alkali Activated

This research presents the influence of ordinary Portland cement (OPC) and/or water glass addition on fly ash alkali-activated mortar and concrete. The results show that fly ash (FA) concrete activated with a NaOH solution and water glass mixture had better resistance to freeze and thaw, carbonation, alkali-silica reaction (ASR) and developed higher compressive strength and static elastic modulus compared with the FA concrete activated only with an NaOH solution. The addition of OPC contributes to the development of a denser microstructure of alkali activated concrete (AAC) samples. In the presence of water glass and OPC, the compressive strength (52.60 MPa) of the samples increased more than two times as compared with the reference sample (21.36 MPa) without OPC and water glass. The combination of OPC and water glass showed the increased strength and enhanced durability of AAC. The samples were more resistant to freeze and thaw, ASR, and carbonation.

scholarly journals Stabilization of Ash and Slag from Combustion of Medical Waste in the Geopolymers Matrix

2018 ◽  
Vol 44 ◽  
pp. 00110 ◽  
Author(s):  
Dariusz Mierzwiński ◽  
Michał Łach ◽  
Janusz Mikuła ◽  
Marcin Goły
Keyword(s):  
Heavy Metals ◽  
Compressive Strength ◽  
Fly Ash ◽  
Coal Combustion ◽  
Water Glass ◽  
Medical Waste ◽  
Waste Materials ◽  
Alkali Activation ◽  
Related Research ◽  
Geopolymer Matrix

This paper regards the possibility of using geopolymer matrix to immobilize heavy metals present in ash and slag from combustion of medical waste. In the related research one used the fly ash from coal combustion in one Polish CHP plant and the waste from two Polish incineration plants. It was studied if the above-named waste materials are useful in the process of alkali-activation. Therefore, two sets of geopolymer mixtures were prepared containing 60 and 50% of ash and slag from the combustion of medical waste. The remaining content was fly ash from coal combustion. The alkali-activation was conducted by means of 14M solution of NaOH and sodium water glass. The samples, whose dimensions were in accordance with the EN 206-1 norm, were subjected to 75°C for 24 h. According to the results, the geopolymer matrix is able to immobilize heavy metals and retain compressive strength resembling that of C8/10 type concrete.

A Study of the Mixing Ratio and Mechanical Properties of Clay-Carbide Slag-Fly Ash Unfired Brick

2011 ◽  
Vol 250-253 ◽  
pp. 849-852
Author(s):  
Wei Xin Hu
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Raw Materials ◽  
Wall Material ◽  
Mixing Ratio ◽  
Environment Friendly ◽  
Atmosphere Pressure ◽  
Carbide Slag ◽  
Water Curing

A new environment-friendly wall material- the unfired brick is produced by using clay, carbide slag, fly ash and cement as the main raw materials，and certain amount of chemical excitator. The primary mixing ratio is designed on the basis of its mechanical properties and durability. When adopting water curing under normal temperature and atmosphere pressure，the compressive strength，flexural strength and frost resistance of the unfired brick are measured. The results reveal that the optimum mixing ratio for unfired brick is: Carbide slag 30%，fly ash 30%，cement 25% and clay 15%. For the unfired brick formed by vibration with the optimum mixing ratio，the min. compressive strength of each brick is more than 10 MPa, the overall properties meet the requirement as specified in standard JC 239—2001“Fly Ash Brick”.

Alkali-Activated Fly Ash Foams – Synthesis, Chemo-Physical Properties and Microstructure Modeling

2014 ◽  
Vol 92 ◽  
pp. 14-19 ◽  
Author(s):  
Petr Hlaváček ◽  
Vit Šmilauer ◽  
František Škvára
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Fly Ash ◽  
Thermal Capacity ◽  
Alkali Activation ◽  
Activation Process ◽  
Strain Diagram ◽  
Element Analysis ◽  
Aluminium Powder ◽  
One Year

Inorganic foams offer several unique properties such as low thermal conductivity, fire resistance, or UV stability. Inorganic foam specimens were synthesized from fly ash and aluminium powder through an alkali-activation process. Depending on mix proportions, bulk densities ranged between 400 and 800 kg/m3. Thermal treatment at 80°C for 12 hours accelerated curing process. Compressive strength was found in the range 4.5-9.0 MPa, flexural strength 0.6-1.7 MPa, Young's modulus 0.6-1.1 GPa, thermal conductivity 0.14-0.16 W/m/K and thermal capacity around 1100 J/kg/K. Exposing the foams to temperature 800°C led to a small decrease of compressive strength while exposure to 1100°C sintered the foam to higher strength of 13 MPa. Volumetric shrinkage 20% occurred at 1100°C without further disintegration. Residual compressive strength was determined after exposure to NaCl, HCl, Na2SO4, MgSO4, H2SO4. The highest reduction to 20% occured in both acids with pH=2 after one year of exposition. Digitized microstructures entered finite element analysis to validate a stress-strain diagram.

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.

scholarly journals A Comprehensive Study on the Factors Affecting the Workability and Mechanical Properties of Ambient Cured Fly Ash and Slag Based Geopolymer Concrete

2021 ◽  
Vol 11 (18) ◽  
pp. 8722
Author(s):  
Rana Muhammad Waqas ◽  
Faheem Butt ◽  
Xulong Zhu ◽  
Tianshui Jiang ◽  
Rana Faisal Tufail
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Fly Ash ◽  
Geopolymer Concrete ◽  
Factors Affecting ◽  
Naoh Solution ◽  
New Material ◽  
Comprehensive Study ◽  
Slag Content

Geopolymer concrete (GPC), also known as an earth friendly concrete, has been under continuous study due to its environmental benefits and potential as a sustainable alternative to conventional concrete construction. However, there is still a lack of comprehensive studies focusing on the influence of all the design mix variables on the fresh and strength properties of GPC. GPC is still a relatively new material in terms of field application and has yet to secure international acceptance as a construction material. Therefore, it is important that comprehensive studies be carried out to collect more reliable information to expand this relatively new material technology to field and site applications. This research work aims to provide a comprehensive study on the factors affecting the fresh and hardened properties of ambient cured fly ash and slag based geopolymer concrete (FS-GPC). Industrial by-products, fly ash from thermal power plants, and ground granulated blast furnace slag from steel industries were utilized to produce ambient cured FS-GPC. A series of experiments were conducted to study the effect of various parameters, i.e., slag content (10%, 20%, 30%, and 50%), amount of alkaline activator solution (AAS) (35% and 40%), sodium silicate (SS) to sodium hydroxide (SH) ratio (SS/SH = 2.0, 2.5 and 3.0), sodium hydroxide concentration (10 M, 12 M, and 14 M) and addition of extra water on fresh and mechanical properties of FS-GPC. The workability of the fresh FS-GPC mixes was measured by the slump cone test. The mechanical properties of the mixes were evaluated by compressive strength, split tensile strength, flexure strength, and static modulus tests. The results revealed that workability of FS-GPC is greatly reduced by increasing slag content, molarity of NaOH solution, and SS/SH ratio. The compressive strength was improved with an increase in the molarity of NaOH solution and slag content and a decrease in AAS content from 40% to 35%. However, the influence of SS/SH ratio on mechanical properties of FS-GPC has a varying effect. The addition of extra water to enhance the workability of GPC matrix caused a decrease in the compressive strength. The validity of the equations suggested by previous studies to estimate the tensile and flexural strength and elastic modulus of FS-GPC mixes were also evaluated. Based on the test results of this study, empirical equations are proposed to predict the splitting tensile strength, flexural strength, and elastic modulus of ambient cured FS-GPC. The optimal mixtures of FS-GPC in terms of workability and mechanical properties were also proposed for the field applications.

scholarly journals Using Fly Ash Wastes for the Development of New Building Materials with Improved Compressive Strength

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 644
Author(s):  
Maria Harja ◽  
Carmen Teodosiu ◽  
Dorina Nicolina Isopescu ◽  
Osman Gencel ◽  
Doina Lutic ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Building Materials ◽  
Simple Procedure ◽  
Xrd Analysis ◽  
Partial Hydrolysis ◽  
Alkali Activation ◽  
Activation Process ◽  
Solid Ratio ◽  
Powder Xrd Analysis

Fly ash wastes (silica, aluminum and iron-rich materials) could be smartly valorized by their incorporation in concrete formulation, partly replacing the cement. The necessary binding properties can be accomplished by a simple procedure: an alkali activation process, involving partial hydrolysis, followed by gel formation and polycondensation. The correlations between the experimental fly ash processing conditions, particle characteristics (size and morphology) and the compressive strength values of the concrete prepared using this material were investigated by performing a parametric optimization study to deduce the optimal processing set of conditions. The alkali activation procedure included the variation of the NaOH solutions concentration (8–12 M), temperature values (25–65 °C) and the liquid/solid ratio (1–3). The activation led to important modifications of the crystallography of the samples (shown by powder XRD analysis), their morphologies (seen by SEM), particle size distribution and Blaine surface values. The values of the compressive strength of concrete prepared using fly ash derivatives were between 16.8–22.6 MPa. Thus, the processed fly ash qualifies as a proper potential building material, solving disposal-associated problems, as well as saving significant amounts of cement consumed in concrete formulation.

The Effect of KOH Concentration on Setting Time and Compressive Strength of Fly Ash-Based Geopolymer

2014 ◽  
Vol 625 ◽  
pp. 94-97 ◽  
Author(s):  
Tia Rahmiati ◽  
Khairun Azizi Azizli ◽  
Zakaria Man ◽  
Lukman Ismail ◽  
Mohd Fadhil Nuruddin
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Fly Ash ◽  
Sodium Hydroxide ◽  
Setting Time ◽  
Alkali Activation ◽  
High Concentration ◽  
Low Concentration ◽  
Optimum Result ◽  
Alkaline Activator

Geopolymer is produced from the alkali activation of materials rich in Si and Al such as fly ash. Sodium hydroxide (NaOH) with high concentration is normally used in geopolymerization. Limited research has been done with low concentration of alkali activator. This study confirms that KOH with low concentration affect the setting time and compressive strength of geopolymer in order to have good mechanical properties. Optimum result was observed at 4.5 M KOH. This result can be further developed to produce geopolymer with low alkaline activator for coating applications.

Sign in / Sign up

Export Citation Format

Share Document