Milestones in the analysis of alkali-activated binders

The use of alkali activation to achieve environmental savings in the production of construction materials is currently an extremely active area of research and development. There is now a diverse range of chemistries and applications that have been developed within the broader theme of ‘alkali-activated materials’, including the subclass of lower-calcium binders which are also known as ‘geopolymers’. Academic research and commercial development have combined to bring these materials to a level of technological maturity where larger scale deployment is now taking place. This paper reviews some of the key aspects of alkali-activation technology which have brought the field to this point, with a particular view towards re-assessing key points and comments which have been raised in several historical reviews and discussions of this class of materials. Conclusions are therefore drawn regarding which among these key questions have been answered, and which remain outstanding in an engineering or scientific sense