A review on the utilization of fly ash

Alkali-activated materials

A review of the multi-component utilisation of coal fly ash

NaOH-activated ground fly ash geopolymer cured at ambient temperature

Fly ash-based geopolymer: clean production, properties and applications

Effect of synthesis parameters on the mechanical properties of fly ash-based geopolymers

Geopolymerization is an innovative technology that can transform several solid aluminosilicate materials into useful products called geopolymers or inorganic polymers. Although the geopolymerization mechanism is not well understood, the most proposed mechanism includes four parallel stages: (a) dissolution of solid aluminosilicate materials in alkaline sodium silicate solution, (b) oligomerization of Si and/or Si–Al in aqueous phase, (c) polymerization of the oligomeric species, and (d) bonding of undissolved solid particles in the polymer. It is obvious that polymerization in sodium silicate solutions comprises a fundamental process in geopolymerization technology. Therefore, this article aims at studying experimentally the polymerization stage in synthetic pure sodium silicate solutions. The structure of sodium silicate gels as a function of the SiO2/Na2O molar ratio is examined and their hardness as well as hydrolytic stability are determined. In addition, the effect of aluminum incorporation in the hydrolytic stability of these gels is also examined. Finally, the structure of sodium silicate and aluminosilicate gels is correlated to the measured properties drawing very useful conclusions that could be applied on geopolymerization technology.

Polymerization in sodium silicate solutions: a fundamental process in geopolymerization technology

Synthesis of ferronickel slag-based geopolymers

Red mud is a residue coming from the metallurgical treatment of bauxite with the Bayer process. Million of tons of red mud are produced annually worldwide and disposed of on land, degrading vast areas. Therefore, red mud utilization is a first-priority issue for any alumina plant. In the present work, the potential use of red mud for synthesis of inorganic polymeric materials through geopolymerization process was studied. The main focus was the production of inorganic polymeric materials that could be used in the construction sector as artificial structural elements such as massive bricks. The geopolymerization process involves a chemical reaction between red mud and alkali metal silicate solution under highly alkaline conditions. The product of this reaction is an amorphous to semi-crystalline polymeric structure, which binds the individual particles of red mud transforming the initial granular material to a compact and strong one. The effect of main synthesis parameters—like solid-to-liquid ratio, caust...

Utilization of alumina red mud for synthesis of inorganic polymeric materials

This paper deals with the geopolymerization of the red mud generated in the primary aluminium production and the slag generated in the ferronickel production, in order to develop inorganic polymeric materials with advanced mechanical and physical properties. In particular, the effect of the main synthesis parameters of the inorganic polymeric materials on their mechanical strength and water absorption was investigated. Moreover, the structure of the inorganic polymeric materials was studied according to X-ray Diffraction analysis, Fourier Transform Infra Red spectroscopy and Scanning Electronic Microscopy. The inorganic polymeric materials produced by the geopolymerization of the red mud developed compressive strength up to 21 MPa and presented water absorption lower than 3 %, while the geopolymerization of the ferronickel slag resulted in materials with compressive strength higher than 110 MPa and extremely low water absorption (< 1 %). According to these results, the developed materials may be viewed as alternatives in the industrial sectors of construction and building materials.

/pdf/utilization-of-metallurgical-solid-by-products-for-the-2t5n70lddj.pdf

Ioanna Giannopoulou

Papers

Effect of synthesis parameters on the mechanical properties of fly ash-based geopolymers

Polymerization in sodium silicate solutions: a fundamental process in geopolymerization technology

Synthesis of ferronickel slag-based geopolymers

Utilization of alumina red mud for synthesis of inorganic polymeric materials

Utilization of metallurgical solid by-products for the development of inorganic polymeric construction materials