During 1978, French scientist Joseph Davidovits has invented "Geopolymer" by the process of Geopolymerisation-a green chemistry. Recent and forthcoming researches in geopolymer technology will revolutionize construction industry and will coerce a novel era of green construction materials through replacement of OPC by GPC. The geopolymer concrete has been accepted as a more durable "green" concrete with less energy consumption and nine time less emission of Carbon Dioxide compared to OPC concrete, which in turn, results in mitigation to global warming- a fiery dilemma. This book is an attempt to understand Fly ash and slag based Geopolymer concrete in detail which include an extensive experimental studies on effect of various parameters viz. ratio of Sodium Silicate to Sodium Hydroxide solution, addition of water, rest period, curing temperatures, curing time, different curing methods, addition of super plasticisers on Fly ash and slag based geopolymer concrete. The final part of this book describes the effect of addition of Fly ash and Slag on mechanical properties of geopolymer concrete like compressive strength, Split-tensile strength, Flexural strength and Modulus of Elasticity.