Effect of Mechanical Activation on Properties of Alkali Activated Binders

2014 ◽  
Vol 1000 ◽  
pp. 67-70 ◽  
Author(s):  
Martin Sisol ◽  
Juraj Mosej ◽  
Miroslava Drabová ◽  
Ivan Brezani
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Mechanical Activation ◽  
Sodium Hydroxide ◽  
Water Glass ◽  
Fly Ashes ◽  
Alkali Activated Binders ◽  
Alkali Activated

Effect of mechanical activation of fly ashes on strength of alkali activated binders is investigated. Four different kinds of fly ashes are mechanically activated. The aim of mechanical activation is to increase the reactivity of fly ashes. Mechanically activated fly ash is used as an admixture to the untreated original fly ash in proportion of 0, 50, 75 and 100 %. Fly ashes are alkali activated with solutions containing sodium hydroxide and sodium water glass. Compressive and flexural strength is tested on hardened alkali activated binders.

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 Monitoring the course of early-age reactions in alkali activated aluminosilicates

2019 ◽  
Vol 282 ◽  
pp. 02056
Author(s):  
Miloš Jerman ◽  
Vratislav Tydlitát ◽  
Robert Černý
Keyword(s):  
Heat Flow ◽  
Sodium Hydroxide ◽  
Water Glass ◽  
Early Time ◽  
Early Age ◽  
Heat Power ◽  
Reaction Heat ◽  
Flow Calorimeter ◽  
Isothermal Heat Flow Calorimeter ◽  
Alkali Activated

In this paper the reaction heat development of alkali activated aluminosilicates is studied by an isothermal heat flow calorimeter. The highest reaction activity is observed during two hours after mixing. The hydration heat power at early time is influenced mainly by the composition of tested mixtures involving ceramic dust as precursor and different amounts of sodium hydroxide and water glass as activators and by temperature.

scholarly journals Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1673 ◽  
Author(s):  
Hyeongmin Son ◽  
Sol Moi Park ◽  
Joon Ho Seo ◽  
Haeng Ki Lee
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Activated Slag ◽  
Capillary Tension ◽  
Alkali Activated Binders ◽  
Internal Pore Structure ◽  
Alkali Activated

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

Influence of Different Mineral Precursors on the Properties of Fly Ash Based Alkali-Activated Mortars

2018 ◽  
Vol 761 ◽  
pp. 73-78 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Chemical Composition ◽  
Coal Combustion ◽  
Pure Aluminum ◽  
Partial Replacement ◽  
Black Coal ◽  
Fly Ashes ◽  
Final Composition ◽  
Alkali Activated

Alkali-activated materials based on fly ash are widely developed and also produced on the present. Some of fly ashes are not suitable for production of alkali-activated materials because of their inconvenient chemical composition. Alumina-silicates are the most important components that are needed to accomplish the successful reaction. The proper content of amorphous phase of alumina-silicates and its proportion as well should be provided for the final composition of alkali-activated materials. The influence of pure aluminum oxide powder as well as raw milled natural perlite on mechanical properties and durability of alkali-activated mortars was investigated. These minerals were used as partial replacement of fly ash coming from black coal combustion. In addition, the mortars were prepared by using different alkali activators.

scholarly journals Leaching, carbonation and chloride ingress in reinforced alkali-activated fly ash mortars

2018 ◽  
Vol 199 ◽  
pp. 02025 ◽  
Author(s):  
Gregor J. G. Gluth ◽  
Petr Hlaváček ◽  
Steffi Reinemann ◽  
Gino Ebell ◽  
Jürgen Mietz
Keyword(s):  
Fly Ash ◽  
Visual Inspection ◽  
Electrochemical Behaviour ◽  
Transport Coefficients ◽  
Chloride Penetration ◽  
Chloride Ingress ◽  
Reaction Products ◽  
Steel Bars ◽  
Alkali Activated Binders ◽  
Alkali Activated

Alkali-activated fly ash mortars were studied with regard to durability-relevant transport coefficients and the electrochemical behaviour of embedded carbon steel bars on exposure of the mortars to leaching, carbonation and chloride penetration environments. The transport coefficients differed considerably between different formulations, being lowest for a mortar with BFS addition, but still acceptable for one of the purely fly ash-based mortars. Leaching over a period of ~300 days in de-ionized water did not lead to observable corrosion of the embedded steel, as shown by the electrochemical data and visual inspection of the steel. Exposure to 100 % CO2 atmosphere caused steel depassivation within approx. two weeks; in addition, indications of a deterioration of the mortar were observed. The results are discussed in the context of the different reaction products expected in highand low-Ca alkali-activated binders, and the alterations caused by leaching and carbonation.

Mechanical Properties of Mortars Prepared by Alkali Activated Fly Ash Coming from Different Production Batches

2015 ◽  
Vol 244 ◽  
pp. 140-145 ◽  
Author(s):  
Matej Špak ◽  
Pavel Raschman
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Construction Materials ◽  
Chemical Properties ◽  
Raw Material ◽  
Fly Ashes ◽  
Coal Burning ◽  
Alkali Solutions ◽  
One Year ◽  
Alkali Activated

Fly ash is a well utilizable secondary raw material for the production of alkali activated construction materials. It is a significant alumina-silicates source suitable for the chemical reaction resulting in hardened composites. Physical and chemical properties of fly ashes as a co-product of coal burning mainly depend on characteristics of coal, burning temperature and combustion conditions. High variability of the properties of fly ash causes an uncertainty in the properties of alkali activated mortars. Time behaviour of the composition of the fly ash produced in a heating plant located in Košice, Slovakia as well as leaching behaviour of both alumina and silica from particular batches during one-year period was documented. Leaching tests were carried out using the distilled water and alkali solutions with three different concentrations. Both compressive and tensile strengths of alkali activated mortars were measured, and the correlation between the mechanical properties of hardened mortars and the chemical composition of fly ashes as well as their leaching characteristics was investigated.

scholarly journals Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

2018 ◽  
Vol 10 (10) ◽  
pp. 3538 ◽  
Author(s):  
Sol Park ◽  
Hammad Khalid ◽  
Joon Seo ◽  
Hyun Yoon ◽  
Hyeong Son ◽  
...  
Keyword(s):  
Fly Ash ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Sodium Silicate Solution ◽  
Silicate Solution ◽  
Elevated Pressure ◽  
X Ray Diffraction ◽  
27Al Mas Nmr ◽  
Alkali Activated

The present study investigated geopolymerization in alkali-activated fly ash under elevated pressure conditions. The fly ash was activated using either sodium hydroxide or a combination of sodium silicate solution and sodium hydroxide, and was cured at 120 °C at a pressure of 0.22 MPa for the first 24 h. The pressure-induced evolution of the binder gel in the alkali-activated fly ash was investigated by employing synchrotron X-ray diffraction and solid-state 29Si and 27Al MAS NMR spectroscopy. The results showed that the reactivity of the raw fly ash and the growth of the zeolite crystals were significantly enhanced in the samples activated with sodium hydroxide. In contrast, the effects of the elevated pressure conditions were found to be less apparent in the samples activated with the sodium silicate solution. These results may have important implications for the binder design of geopolymers, since the crystallization of geopolymers relates highly to its long-term properties and functionality.

Research on Mechanism of Architectural Wastes Solidified by Alkali-Activated Cement and Fly Ash

2012 ◽  
Vol 446-449 ◽  
pp. 2708-2713 ◽  
Author(s):  
Qin Li ◽  
Xiao Jun Zhou ◽  
Zhuo Yin Jiang ◽  
Ke Wei Sun
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Hydration Products ◽  
Testing Methods ◽  
Fly Ashes ◽  
Comparison Research ◽  
Cement System ◽  
Cementitious System ◽  
Micro Morphology ◽  
Alkali Activated

An comparison research on the effect of pozzolanic reactions of fly ashes in architectural wastes recycle is described in the paper. In the experiment, NaOH and Na2SO4-Ca(OH)2 were used to activate the pozzolanic activities in the fly ashes—cement system to solidify the architectural wastes. The macro and micro testing methods were used to test the compressive strength, phase and electronic micro morphology of the hydration of alkali-activated fly ashes—cement cementitious system. The testing result shows that proper alkali-activated fly ashes—cement cementitious architectural wastes can shorten the incubation time of the pozzolanic reactions of fly ashes, whi ch make the reactions of fly ashes more sufficient. So the hydration products of fly ashes —cement cementitious system with alkali additions were more than those of without alkali add itions, and the compressive strength of the alkali-activated fly ashes—cement cementitious system is higher than that of non alkali-activated fly ashes—cement cementitious system.

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