Geopolymers are a solidified product produced by the polycondensation reaction of an alkali silica solution such as water glass and an alumina silica powder such as fly ash. Geopolymers have attracted interest in recent years as a material having performance equal to or higher than that of Portland cement. The characteristics of geopolymers are wide-ranging, from the large reduction of CO₂ emissions and mass consumption of industrial byproducts such as fly ash, to fixation of heavy metals and radioactive waste. On the other hand, elucidation of the solidification mechanism of geopolymers, and if they are to be used as a substitute for cement concrete, improvement of workability and the accumulation of data on durability, are required. This paper first explains the materials used for geopolymers and their solidification mechanism, their expected effects and current challenges, and then introduces the basic physical properties of geopolymers such as strength and durability, the current state of geopolymer research in Japan and overseas, and examples of the practical application of geopolymers.

We built a structural health monitoring system (experimental version and practical version) that instantly evaluates the degree of damage of a building based on the data of sensors that detect the shaking of the building. This system evaluates the structural health of the building immediately after an earthquake by the response estimation method using a small number of acceleration sensors. Application of the experimental version of this system in the collapse test of a 6-story RC building at E-Defense to verify the accuracy of the response estimation method confirmed that the proposed structural health monitoring system can be applied to middle-rise RC buildings with earthquake resistant walls, even up to the weakly nonlinear region. Moreover, it was confirmed that the monitoring results of the practical version system agree well with the results of conventional visual emergency safety checks and post-earthquake damage evaluation.