Related Experiment Video
Updated: Jun 29, 2025
12:12
On the Preparation and Testing of Fuel Cell Catalysts Using the Thin Film Rotating Disk Electrode Method
Published on: March 16, 2018
22.0K
Alkaline Activation of Binders: A Comparative Study.
Bianca Ignacio Almeida Alves1, Markssuel Teixeira Marvila2, José Alexandre Tostes Linhares Júnior1
1LAMAV-Advanced Materials Laboratory, UENF-University of the Northern Rio de Janeiro, Av. Alberto Lamego, 2000, Campos dos Goytacazes 28013-602, Brazil.
Materials (Basel, Switzerland)
|April 9, 2024
Summary
Activated alkali materials (AAM) offer a sustainable alternative to Portland cement. This study found that metakaolin-based AAM achieved approximately 30 MPa compressive strength, while blast furnace slag AAM reached around 25 MPa after 7 days.
Area of Science:
- Materials Science
- Sustainable Construction
- Geochemistry
Background:
- Portland cement production has significant CO2 emissions, driving the need for sustainable alternatives.
- Activated alkali materials (AAM) are emerging as eco-friendly binders.
- Blast furnace slag, fly ash, and metakaolin are key precursors for AAM.
Purpose of the Study:
- To evaluate the properties of AAM produced from blast furnace slag, fly ash, and metakaolin.
- To compare the performance of these AAM as potential replacements for Portland cement.
- To understand the activation mechanisms of different precursors.
Main Methods:
- Characterization of binders (chemical, mineralogical, granulometric composition).
- Preparation of AAM specimens with varying alkali activator molarity (4.00-5.50 mol/L).
- Evaluation of fresh and hardened properties: consistency, viscosity, water absorption, density, compressive strength (7 days), calorimetry, XRD, and SEM.
Main Results:
- Metakaolin-based AAM showed the lowest workability but optimized compressive strength (~30 MPa at 7 days) with normal cure and 4.0-4.5 mol/L molarity.
- Fly ash activation was least intense, with no distinct crystalline phases observed via XRD.
- Blast furnace slag AAM exhibited higher reactivity with thermal curing, achieving ~25 MPa compressive strength at 7 days.
Conclusions:
- Each precursor (metakaolin, fly ash, blast furnace slag) exhibits a unique alkali activation mechanism.
- AAM produced from these precursors demonstrate potential as viable, sustainable alternatives to Portland cement.
- Further research into alkaline activation can advance cement technology and reduce environmental impact.
More Related Videos
Related Concept Videos
01:21Basicity of Aliphatic Amines
5.9K
Amines can behave as Brønsted–Lowry bases by accepting a proton from the acid to form corresponding conjugate acids. Due to a lone pair of nonbonding electrons, aliphatic amines can also act as Lewis bases by forming a covalent bond with an electrophile.
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates...
To measure the basicity of amines, two conventions are generally used. The first defines Kb as the basicity constant for the deprotonation reaction of water by the amine, as presented in Figure 1. Conventionally, lower Kb indicates...
5.9K
01:29Leveling Effect
800
In acid-base chemistry, the leveling effect refers to the limitation imposed by the solvent on the strength of acids and bases in solution. When a base stronger than the solvent's conjugate base is used, it deprotonates the solvent until the base is entirely consumed, making it ineffective against weaker acids. Conversely, an acid stronger than the solvent's conjugate acid protonates the solvent until the acid is depleted, rendering it ineffective against weaker bases. Essentially, the...
800
00:49Ligand Binding and Linkage
4.8K
Allosteric proteins have more than one ligand binding site; the binding of a ligand to any of these sites influences the binding of ligands to the other sites. When a protein is allosteric, its binding sites are called coupled or linked. In the case of enzymes, the site that binds to the substrate is known as the active site and the other site is known as the regulatory site. When a ligand binds to the regulatory site, this leads to conformational changes in the protein that can influence...
4.8K
02:11Leveling Effect and Non-Aqueous Acid-Base Solutions
8.1K
This lesson defines the leveling effect in acidic and basic solutions and its role in aqueous and non-aqueous solutions. It is essential to understand the competing nature of various species in a chemical system.
The Leveling Effect of a Solvent
A generic acid (HA) reacts with the generic base (B-) to yield the corresponding conjugate base (A-) and conjugate acid (HB):
The Leveling Effect of a Solvent
A generic acid (HA) reacts with the generic base (B-) to yield the corresponding conjugate base (A-) and conjugate acid (HB):
8.1K
01:10Factors Affecting α-Alkylation of Ketones: Choice of Base
3.2K
α-Alkylation of ketones is achieved in the presence of alkyl halides and a base. The reaction proceeds via the formation of an enolate ion followed by nucleophilic substitution. The choice of base employed is essential as it is the key factor in determining the reaction outcome.
The reaction involving bases like EtO− whose conjugate acid EtOH (pKa = 15.9) is stronger than the ketone (pKa = 19.2) results in an equilibrium mixture with higher ketone concentration. As a consequence,...
The reaction involving bases like EtO− whose conjugate acid EtOH (pKa = 15.9) is stronger than the ketone (pKa = 19.2) results in an equilibrium mixture with higher ketone concentration. As a consequence,...
3.2K
01:16Titration in Nonaqueous Solvents
794
Most acid-base titrations are performed in an aqueous medium. In aqueous titrations, water competes with weaker acids or bases for proton donation or acceptance, leading to ambiguous endpoints in the titration curve. Water also affects the partial ionization of weak acids or bases. For example, water accepts a proton from acetic acid to form hydronium and acetate ions. The hydronium ion formed is a stronger acid than acetic acid, and the acetate ion is a stronger base than water. As a result,...
794