Effect of Phosphates on the Hydration Process of Alkali Activated Materials

2016 ◽  
Vol 851 ◽  
pp. 63-68
Author(s):  
Lukáš Kalina ◽  
Vlastimil Bílek Jr. ◽  
Kateřina Komosná ◽  
Radoslav Novotný ◽  
Jakub Tkacz
Keyword(s):  
Electron Microscopy ◽  
Blast Furnace Slag ◽  
Heat Evolution ◽  
Hydration Reaction ◽  
Optimal Dosage ◽  
Initial Setting ◽  
Activated Slag ◽  
The One ◽  
Furnace Slag ◽  
Alkali Activated

The study deals with the one of the important feature of alkali activated blast furnace slag which is very rapid initial setting. Therefore, the influence of the retarding agents such as phosphates was tested. It is shown that phosphates decreases the hydration heat evolution and retards the hydration reaction of alkali activated slag effectively. The mechanism of retardation is studied through the microcalorimeter and electron microscopy equipped with energy dispersive analyzer (SEM-EDS). The optimal dosage of suitable retarding admixture in the means of mechanical properties has been determined.

Possibilities of Using Plasticizers in Alkali-Activated Systems

2016 ◽  
Vol 851 ◽  
pp. 57-62
Author(s):  
Lukáš Kalina ◽  
Miroslava Hajdúchová ◽  
Markéta Langová ◽  
Vojtěch Enev
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Preparation Process ◽  
The Stability ◽  
Activated Slag ◽  
Plasticizing Admixture ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Convenient Dose

The study deals with the preparation process and properties of alkali-activated blast furnace slag with different addition of lignosulphonate plasticizer. The goal of this study is to evaluate the suitability of plasticizer and find the convenient dose of this admixture, which improve the workability and mechanical properties of alkali-activated slag. The stability of plasticizing admixture in alkali environment was studied by infrared spectroscopy (FTIR).

scholarly journals The Effects of Aluminium Sulphate on Slag Paste Activated with Sodium Hydroxide and Sodium Silicate

Materials ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2286
Author(s):  
Taewan Kim ◽  
Sungnam Hong ◽  
Choonghyun Kang
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Sodium Hydroxide ◽  
Blast Furnace Slag ◽  
Aluminium Sulphate ◽  
The Third ◽  
Granulated Blast Furnace Slag ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

This study investigates the characteristics of alkali-activated slag cement using aluminium sulphate (ALS) as an activator. The alkalis NaOH and Na2SiO3 were used as additional activators (denoted by alkali) at 5% and 10% of the weight of the ground granulated blast furnace slag (GGBFS). Three types of activators were considered. The first was when ALS was used alone. For the second, ALS and 5% alkali were used together. The third was when ALS and 10% alkali were used. ALS was used at concentrations of 2%, 4%, 6%, 8%, and 10% based on binder weight. Experimental results show that when ALS was used as a sole activator, the activity of GGBFS was low and its strength was below 1 MPa. However, compressive strength was improved when 5% or 10% alkali and ALS were used at the same time. This was effective at improving mechanical and microstructural performance when used with an additional activator capable of forming a more alkaline environment than using ALS as a sole activator.

scholarly journals Autogenous Deformation of Alkali-Activated Blast Furnace Slag Concrete Subjected to Variable Curing Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Katalin Orosz ◽  
Abeer Humad ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Blast Furnace ◽  
Diffraction Analysis ◽  
Sodium Silicate ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

Deformations of alkali-activated slag concrete (AASC) with high MgO and Al2O3 content, subjected to variable curing temperature were studied. Sodium silicate and sodium carbonate were used as alkali activators. The obtained results showed development of deformations consisting of both shrinkage and expansion. Shrinkage appeared not to be affected by the activator type, while the expansion developed after the cooling down phase in stabilized isothermal conditions and did not stop within the duration of the tests. X-ray diffraction analysis performed shortly after the cooling down phase indicated the formation of crystalline hydrotalcite, which was associated with the observed expansion. A mixture with a higher amount of sodium silicate showed less expansion, likely due to the accelerated hydration and geopolymerization leading to the increased stiffness of the binder matrix.

Effect of Sodium Hydroxide (NaOH) Concentration on Compressive Strength of Alkali-Activated Slag (AAS) Mortars

2015 ◽  
Vol 754-755 ◽  
pp. 300-304 ◽  
Author(s):  
Aimi Noorliyana Hashim ◽  
Kamarudin Hussin ◽  
Noorzahan Begum ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Kamrosni Abdul Razak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Sodium Hydroxide ◽  
Blast Furnace Slag ◽  
Alkali Activated Slag ◽  
Granulated Blast Furnace Slag ◽  
Environmental Friendly ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

Energy saving in building technology is among the most critical problems in the world. Thus it is a need to develop sustainable alternatives to conventional concrete utilizing more environmental friendly materials. One of the possibilities to work out is the massive usage of industrial wastes like ground granulated blast furnace slag (GGBS) to turn them to useful environmental friendly and technologically advantageous cementitious materials. In this study, ground granulated blast furnace slag (GGBS) is used to produce of alkali activated slag (AAS) mortar with the effect of alkaline activator concentration. Alkali activated slag (AAS) mortar is accelerated using alkaline solution of sodium silicate mixed with sodium hydroxide. The fixed ratio of sodium silicate to sodium hydroxide is 1.7 and the concentration of sodium hydroxide is varied from 6M to 12M. Concentration of 10M NaOH promotes the best properties of mortar by achieving the greatest compressive strength. Substitution of mineral admixture also influences strength performance of AAS mortars. The mortar with 20% calcium carbonate demonstrates the maximum compressive strength. The used of alkaline activation system is the best method to prepare industrial byproduct concrete. Moreover, alkali activated product itself gains superior properties which lead to the system become the most interesting method to produce sustainable concrete.

Alkali Activation of Blast Furnace Slag by Various Types of Activators

2015 ◽  
Vol 244 ◽  
pp. 94-101 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Josef Koňařík ◽  
Petr Závrský
Keyword(s):  
Blast Furnace ◽  
Frost Resistance ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Inorganic Materials ◽  
Alkali Activation ◽  
Initial Setting Time ◽  
Initial Setting ◽  
Furnace Slag ◽  
Alkali Activated

Alkali-activated systems, formed by the alkaline activation are inorganic materials characterized by the potential of ecological use. The objective of experiment was to investigate the influence of different activators on selected properties of alkali-activated systems based on granulated blast furnace slag. At the beginning of the experiment, 21 different samples prepared of 12 types of activators were tested to the basic properties. Then, selected samples with the best potencial to use were tested to compressive and flexural strength, frost resistance and surface resistance to chemical de-icing substances. The initial setting time achieved 25 - 95 minutes and final setting time achieved 30 - 105 minutes, compressive strengths were in the range 40 - 100MPa, frost resistance and resistance of surface to water and defrosting chemicals were confirmed.

scholarly journals Interfacial Transition Zone Between Aggregate And Alkali-Activated Blast Furnace Slag – A Scanning Electron Microscopy

2018 ◽  
Vol 64 (4) ◽  
pp. 23-27
Author(s):  
Pavel Mec ◽  
Lucie Gembalová
Keyword(s):  
Electron Microscopy ◽  
Blast Furnace Slag ◽  
Raw Materials ◽  
Interfacial Transition Zone ◽  
Cement Concrete ◽  
Metallurgical Production ◽  
Bonding Phase ◽  
Alkali Activated Binders ◽  
Furnace Slag ◽  
Alkali Activated

Abstract Alkali-activated binders are currently a widely-researched material. Thanks to the use of secondary raw materials such as slag from metallurgical production and ash from combustion, it appears to be a more promising and more environmentally friendly material than conventional cement concrete. Considerable attention is paid to the bonding phase itself, but only a few works deal with the binder-aggregate interaction. With cement concrete, much more attention is paid to this issue. This paper deals with the possibility of observation using electron microscopy and the information that can be obtained by this method. The problems of sample preparation and difficulties in the course of our own observation are observed.

scholarly journals Utilization of Blast Furnace Slag for Immobilization of Copper Ions from Solution

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Martin MUCHA ◽  
Lenka BLÁHOVÁ ◽  
Karolína PEŠOVÁ ◽  
Tomáš JUŘICA ◽  
Dimitrij KOLNIČENKO
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Structural Changes ◽  
Copper Ions ◽  
Alkali Activated Slag ◽  
The Matrix ◽  
Alkaline Conditions ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

Disposal of wastes containing metal ions such as Cu(II) ions is serious problem nowadays. Various materials are utilized for thepurpose of immobilization of Cu(II) ions. Attractive type of material is represented by slags – waste from the metallurgical industry.Raw and alkali-activated blast furnace slag were studied for the purpose of immobilization of Cu(II) ions from the aqueoussolution and for disposal of Cu(II) containing wastes. Slags were saturated by Cu(II) ions. Amount of Cu(II) deposited on the rawslag was 6.35 ± 0.12 mg/g and amount deposited on the alkali-activated slag was 151.37 ± 0.95 mg/g. The saturated materialswere thermally treated at 100, 500, and 1000°C. The thermal treatment leads to the slight structural changes in the case of rawslag and to the significant structural changes in the case of alkali-activated slag. Cu(II) ions probably incorporate to the matrix ofmaterials. The materials based on alkali-activated slag exhibit higher stability to the leaching of Cu(II) ions compared to raw slagbased materials when only 0.13% of the total immobilized amount of Cu(II) ions was released to the solutions during the leachingexperiment in the case of alkali activated slag compared to 12% in the case of raw slag. The higher temperature of treatment leadsto more stable material in the case of both initial slags. The studied materials are less stable under the acidic conditions in comparisonwith the neutral and alkaline conditions. Alkali-activated blast furnace slag could be promising material for the Cu(II) ionsimmobilization and for the safe disposal of Cu(II) containing wastes.

Sign in / Sign up

Export Citation Format

Share Document