Chemistry of High-calcium Fly Ash in Silico-aluminophosphate Geopolymer

Yanshuai Wang, Jian-Guo Dai

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review


The synthesis of alkali-aluminosilicate geopolymer using high-calcium fly ash (FA) at ambient temperature was a great challenge. In this paper, high-calcium FA is used to partially replace the aluminosilicate precursor to seed the calcium source into silico-aluminophosphate geopolymer, which enhances the properties of the geopolymer owning to the physical and chemical actions of FA particles. Addtion of high-calcium FA is found to physically improve the workability of the fresh silico-aluminophosphate geopolymer cement. In the meantime, acid-base or/and hydrolysis reaction between the alkaline calcium species in FA and the acidic phosphate species in the activator is also induced. This chemical process produces calcium phosphate compounds, e.g., brushite and monetite. Since the acid-base or/and hydrolysis reaction is generally fast, the silico-aluminophosphate geopolymer can achieve good setting time and early mechanical performance when the high-calcium FA is blended with aluminosilicate precursors, paving a new avenue for utilizing the high-calcium FA for production of silico-aluminophosphate geopolymer paste at ambient temperature.
Original languageEnglish
Title of host publicationSustainability and Innovation in Concrete Materials and Structures
EditorsBaochun Chen, Jiangang Wei
PublisherThailand Concrete Association under Authorization of Asian Concrete Federation
Number of pages10
ISBN (Print)978-616-91987-6-5
Publication statusPublished - 2018
EventThe 8th International Conference of Asian Concrete Federation - Fuzhou, China
Duration: 4 Nov 20187 Nov 2018


ConferenceThe 8th International Conference of Asian Concrete Federation


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