Strength Development of Heat Cured and Ambient Cured Sodium Hydroxide Activated Fly Ash Based Geopolymer

Atiş C. D., Ali Ali O. A., Durak U., İlkentapar S., Karahan O.

Dicle Üniversitesi Fen Bilimleri Enstitüsü Dergisi, vol.9, no.2, pp.79-88, 2020 (Peer-Reviewed Journal)


Compressive strength development of class F fly ash geopolymer activated by 

sodium hydroxide was compared between initial heat curing at  75ºC for 24 

hours and the ambient medium. Class F geopolymeric mortar was produced 

with  standard  Rilem  sand,  sodium  hydroxide,  and  water.  Mortar  mixtures 

ratios were 3, 1, and 0.288 for sand, fly ash, and water, respectively.   Some 

samples were cured in laboratory conditions; some samples were heat cured 

for 24 hours at 75ºC. Ambient curing medium result with non-measurable low 

compressive strength up to 7 days, however significant strength development 

observed in longer curing time up to six months. Heat curing developed higher 

strength at all times than ambient curing did. It was concluded that heat cured 

geopolymer  samples  could  be  utilized  in  construction  materials,  while 

utilization of non-heat cured samples was not practical due to its longer curing 

duration needs.