Characteristic study of geopolymer fly ash sand as a replacement to natural river sand

The increase in construction activities is leading to the depletion and the exploitation of the natural river sand, causing adverse effects on the environment. Therefore there is an urgent need to find an alternative substitute or replacement of natural river sand. Presently crushed sand or high volume fly ash are used as natural sand replacement, however geoploymer fly ash sand could be better environment friendly replacement. In this research geopolymer fly ash sand (GFS) particles are prepared by geopolymerising fly ash and its properties are compared with natural sand which yield satisfactory results in terms of physical, chemical, mechanical and durability properties. GFS has comparable specific gravity (2.46), good particle size distribution (zone-I) and frictional angle (42°) as compared to natural river sand (NRS). Though GFS has pH (12.2) value and water absorption (5.61%) value slightly higher than the NRS, the soundness and the alkali silica reaction are within limits as per Indian Standard code. The mortar specimens with GFS achieved 93.6% at 28 day compressive strength as compared to NRS, indicating GFS has the potential to replace natural river sand in construction activities.