Hardening evolution of geopolymers from setting to equilibrium: A review

In recent years, environmentally sustainable geopolymers have been widely investigated to obtain comparable mechanical properties with Portland cement, and they are now close to being in a position where they can substitute parts of the cement production utilized in construction. However, in order for geopolymers to reach their full potential, it is crucial to understand the influence of various parameters (e.g., particle size, treatment of precursor, chemical composition) on the hardening evolution at earlier ages of the pastes and the resulting final mechanical strength of the set system. Hence, this paper reviews known factors that influence the setting time of fresh geopolymers and discusses the underlying chemical- and physical-mechanisms of each parameter. Next to this, the interconnection between the setting time and mechanical strength is discussed. This will provide a platform for researchers and engineers to understand the hardening evolution of geopolymers in a broader range.