geopolymer concrete based on class c fly ash cured at ambient condition

geopolymer concrete based on class c fly ash cured at ambient condition

in  recent  years,  geopolymers,  as  a  new  class  of  green  cement  binders,  have  been  considered  as  an environmental-friendly  alternative  to  ordinary  portland  cement  (opc),  which  can  potentially  reduce  the negative environmental impacts of opc. geopolymers are inorganic alumina-silicate materials produced from raw materials in combination with an alkaline activator solution.

the alkaline activator solution is one of the pillars of the geopolymerization process, playing an important role in the formation of crystalline structures of si and al. therefore, it seems necessary to study the impact of various alkaline activator solutions on the mechanical strength of geopolymer concrete (gpc). on the other hand, in most previous research in this regard, gpc based on class f fly ash and high-temperature curing condition have been studied.

hence, in this research, class c fly ash, and ambient curing conditions were used to make gpc. the obtained results indicated  that  in  ambient  curing  conditions,  using  sodium  hydroxide  and  sodium  silicate  results  in  higher compressive  strength  and  lower  permeability  compared  to  potassium-based  (potassium  hydroxide  and potassium silicate) and a combination of sodium potassium-based alkaline activator solutions.

but, at elevated curing  temperatures,  a  potassium-based  activator  provided  higher  compressive  strength.  moreover, simultaneous  inclusion  of  naoh  and  koh  led  to  a  decline  the  compressive  strength.  furthermore,  the obtained results indicated that increasing the naoh and koh concentration resulted in higher compressive strength. the optimal sio2/na2o ratio was 2 in the case of using 14m naoh solution and 2.5 in the case of using 10m naoh solution.