Fig. 9presents the scanning electron micrographs obtained for
the hardened pastes of GBFS activated by sodium hydroxide,
GBFS-NC9 blend (G) and GBFS-NC19 blend (H), at two
magnifications (a) 300lm and (b) 50lm), for 28 days. It is
clear that the micrograph of hardened paste of GBFS-NC9
blend (G) is highly homogeneous and more dense with compact microstructure as compared to GBFS-NC19 (H) or
GBFS activated by sodium hydroxide (I). Also, the content
of calcium silicate hydrate (CSH) formed in GBFS-NC9 (G) blend is greater than that formed in GBFS activated by sodium
hydroxide (I).