Effect of Silica Fume on Strength Enhancement of Geo-Polymer Mortar in Ambient Curing

One of the best alternative binder in place of Portland cement is geo-polymer binder. In geo-polymer binder, the main constituent is fly ash which is rich in silicate and alumina. It reacts with sodium hydroxide/silicate solution to produce alumina silicate gel. This gel binds the fine aggregate to form a good paste-like mortar called geo-polymer mortar (GPM). In this paper, the influence of lime and silica fume towards the strength enhancement of GPM mortar has been studied. Most of the author emphasized on hot curing rather than ambient curing for achieving high strength of geo-polymer matrix. This paper also works out to optimize the sodium silicate to hydroxide proportion, molarity of NaOH, various percentage replacement of lime and silica fume partially with fly ash on enhancement of strength of GPM. It was found out that the compressive strength value increased on increase of molarity of NaOH from 6 to 12 M; similarly, for sodium silicate to sodium hydroxide ratio at 2:1 and also at 7.5 and 3% of lime and silica fume replacement, respectively, better strength was shown.