TY  - JOUR
N2  - Geopolymers are versatile materials possessing excellent mechanical properties and resistance against aggressive environments, these materials present a benefit of improving simultaneously both the environmental and engineering performance as compared to classical conventional materials. This paper determines the geopolymerization kinetics of fly ash based geopolymers using Johnson-Mehl-Avrami-Kolmogorov (JMAK) model. The experiments were designed using Taguchi method by varying four factors (Si/Al ratio, Na/Al ratio, W/S ratio, and curing temperature). The degree of reaction of fly ash (α) was used as a measure of the changes occurring during geopolymerization reaction. The characterization of the cured geopolymers was also carried out. The values of n were in the range of 0.0931â??0.2321 while the values of k were in the range of 0.366â??0.671. According to the JMAK model results, geopolymerization of fly ash based geopolymers is a one dimensional diffusion controlled reaction and its growth follows the mechanism of thickening of large product layers. The mechanism of geopolymerization consists of initial dissolution which is a first order chemical reaction, and further reactions including dissolution, gelation, and polycondensation are the diffusion controlled reactions. The asymmetric stretching band of Si-O-T shifted to 992 cmâ??1 and increased in intensity indicating the formation of geopolymer. Microstructural analysis showed the heterogeneous nature of geopolymers consisting of geopolymer, unreacted fly ash, and different types of needle like structures while one sample showed plate like morphology consistent with the JMAK model results. The geopolymer was found to be an amorphous material with only few peaks due to unreacted crystalline fly ash. © 2016 Elsevier Ltd and Techna Group S.r.l.
IS  - 14
KW  - Amorphous materials; Characterization; Curing; Dissolution; Enzyme kinetics; Fly ash; Gelation; Geopolymers; Kinetics; Taguchi methods
KW  -  Asymmetric stretching bands; Diffusion controlled reactions; Engineering performance; First order chemical reactions; Geopolymer; Jmak models; Johnson-mehl-avrami-kolmogorov; Microstructural analysis
KW  -  Inorganic polymers
ID  - scholars7814
Y1  - 2016///
UR  - https://www.scopus.com/inward/record.uri?eid=2-s2.0-84988952864&doi=10.1016%2fj.ceramint.2016.07.006&partnerID=40&md5=91a171b6aec74cc08e1be54f95596e7f
JF  - Ceramics International
A1  - Siyal, A.A.
A1  - Azizli, K.A.
A1  - Man, Z.
A1  - Ismail, L.
A1  - Khan, M.I.
VL  - 42
AV  - none
N1  - cited By 53
SP  - 15575
TI  - Geopolymerization kinetics of fly ash based geopolymers using JMAK model
SN  - 02728842
PB  - Elsevier Ltd
EP  - 15584
ER  -