Insights into alkali and acid-activated volcanic ash-based materials

A review

authored by: Jean Noel Yankwa Djobo, Sylvain Tome
Abstract: This review provides a comprehensive study of the fundamentals of the alkaline and acid activation of volcanic ashes (VA), for mainstreaming their use as a conventional feedstock for developing geopolymers and their applications. The low reactivity in an alkaline environment is driven by the low content of the amorphous phase and the low solubility of iron, calcium and magnesium at pH > 12. Nevertheless, techniques such as mechanochemical activation has significantly improved the reactivity and the properties of the resulting products. In the acid phosphate medium, the high solubility of iron, calcium and magnesium ensures good reactivity and a high reaction rate at room temperature. As a result, the engineering properties of acid-phosphate-activated volcanic ash are superior to those of alkali-activated volcanic ash. The resulting materials have great potential for use as binders in concrete design, for the stabilization of compressed earth bricks and for the rapid repair of deteriorated concrete structures. However, significant research is required to fully understand their durability performances, life cycle and techno-economic viability for large-scale utilisation. Further, the limited availability of phosphate resources makes acid activation not a viable route to activate volcanic ash for building purposes. The acid-activated volcanic ash has potential in waste management applications such as nuclear waste or heavy metal encapsulation. Finally, volcanic ash emerges as a promising raw material for developing sustainable building materials through alkali and acid activation. This holds as its exploitation is non-disruptive, and processing requires less energy compared to calcined clay or fly ash.
Organisation(s): Institute of Mineralogy
External Organisation(s): Imperial College London
Ministry of Scientific Research and Innovation-Cameroon
University of Douala
Type: Article
Journal: Cement and Concrete Composites
Volume: 152
No. of pages: 13
ISSN: 0958-9465
Publication date: 09.2024
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Building and Construction, General Materials Science
Electronic version(s): https://doi.org/10.1016/j.cemconcomp.2024.105660 (Access: Open)

BibTeX

@article{4ad796f8746546558564b3e9b6541f4c,
title = "Insights into alkali and acid-activated volcanic ash-based materials: A review",
abstract = "This review provides a comprehensive study of the fundamentals of the alkaline and acid activation of volcanic ashes (VA), for mainstreaming their use as a conventional feedstock for developing geopolymers and their applications. The low reactivity in an alkaline environment is driven by the low content of the amorphous phase and the low solubility of iron, calcium and magnesium at pH > 12. Nevertheless, techniques such as mechanochemical activation has significantly improved the reactivity and the properties of the resulting products. In the acid phosphate medium, the high solubility of iron, calcium and magnesium ensures good reactivity and a high reaction rate at room temperature. As a result, the engineering properties of acid-phosphate-activated volcanic ash are superior to those of alkali-activated volcanic ash. The resulting materials have great potential for use as binders in concrete design, for the stabilization of compressed earth bricks and for the rapid repair of deteriorated concrete structures. However, significant research is required to fully understand their durability performances, life cycle and techno-economic viability for large-scale utilisation. Further, the limited availability of phosphate resources makes acid activation not a viable route to activate volcanic ash for building purposes. The acid-activated volcanic ash has potential in waste management applications such as nuclear waste or heavy metal encapsulation. Finally, volcanic ash emerges as a promising raw material for developing sustainable building materials through alkali and acid activation. This holds as its exploitation is non-disruptive, and processing requires less energy compared to calcined clay or fly ash.",
keywords = "Alkaline solution, Building materials, Geopolymer, Phosphoric acid, Volcanic ash",
author = "Djobo, {Jean Noel Yankwa} and Sylvain Tome",
note = "Publisher Copyright: {\textcopyright} 2024 The Authors",
year = "2024",
month = sep,
doi = "10.1016/j.cemconcomp.2024.105660",
language = "English",
volume = "152",
journal = "Cement and Concrete Composites",
issn = "0958-9465",
publisher = "Elsevier Ltd.",
}