Geopolymer, green alkali activated cementitious material: Synthesis, applications and challenges

Geopolymers, combining some characteristics of organic polymers, cements and ceramics for its special poly-condensed network structure, have received extensive attention of the researchers as a green cementitious material because of favorable and unique characteristics. This study mainly presents an overview on the progress of geopolymers research and development in recent decades. The works on raw materials, geopolymerization kinetics, the applications development and challenges of geopolymers are reviewed. This paper focuses on the applications progress of geopolymer as green civil engineering materials, rapidly-repair and dealing with poisonous and radioactive waste materials, coatings, novel ceramic materials, functional composite, three-dimensional printing materials and biological materials, etc. The main contribution of this review is to systematically summarize the complex and diverse of published results on geopolymers application in reality and present future challenges, which is beneficial to the further research activities of civil engineers, environmental scientists, chemists and materials scientists. The current investigation indicates that the geopolymers not only exhibit widespread application prospect to be used as sustainable construction materials, but also have great potential in the fields of three-dimensional printing materials, biological materials and other emerging geopolymer functional materials.