Geo polymers are the materials based on pure aluminosilicate source materials such as fly ash, granulated blast furnace slag obtained from industrial, activated with an alkali metal hydroxide and silicate solution. Geopolymerisation is a complex multiphase exothermic process, involving a series of dissolution-reorientation-solidification reactions analogous to those observed in zeolite synthesis. High alkaline solutions are used to induce the silicon and aluminium atoms in the source material to dissolve and form Geopolymer gel. The sol gel formation (or polymerization) may be assisted by application of heat, followed by drying. The usage of ground granulated blast furnace slug made the geopolymer motor to cure at the room temperature. The Geopolymer gel binds the loose coarse aggregate, fine aggregate and un-reacted source material to form Geopolymer composites. The Portland cement free Geopolymer composites have many advantages like less curing time, earlier development of higher mechanical strength, very little drying shrinkage and very low creep, excellent resistance to sulphate attack, good acid resistance and resistance to high temperature. The strength development in Geopolymer composites depends on the chemical composition, morphology and reactivity of source materials, chemical composition of activating solution and curing process.