Chemistry of High-calcium Fly Ash in Silico-aluminophosphate Geopolymer
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.
High-calcium fly ash Silico-aluminophosphate Geopolymer Brushite Monetite
Yan-Shuai Wang Jian-Guo Dai
Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
国际会议
福州
英文
81-89
2018-11-04（万方平台首次上网日期，不代表论文的发表时间）