2.2.3. Paste
Setting time was tested on geopolymer paste mixes having the
same proportions of binder and alkaline activator of the corresponding
mortar mixes with the fine aggregate excluded.
To investigate the microstructure of OPC blended fly ash based
geopolymers, two paste mixes were prepared containing OPC as
10% and 50% of the total binder (OPC and fly ash). The results were
compared with those of a control fly ash geopolymer paste sample.
Alkaline solution with the ratio of sodium silicate to sodium
hydroxide solution of 2.5 was used as 40% of the total binder. Samples
were cured in room temperature (20–23 C) and investigated
for general microstructural features after 28 days of age.