Abstract
Geopolymers are alternative materials to portland cement, obtained by alkaline activation of
aluminosilicates. They exhibit excellent properties and a wide range of potential applications in
the field of civil engineering. Several natural aluminosilicates and industrial by-products can be
used for geopolymer synthesis, but a lot of starting materials have the disadvantage of poor
reactivity and low strength development. This paper presents a comprehensive review of the main
methods used to alter the reactivity of aluminosilicate materials for geopolymer synthesis, as
reported recently in the literature. The methods consist of mechanical, thermal, physical separation
and chemical activation, of which mechanical activation is the most commonly employed
technique. The reactivity of the activated aluminosilicate materials is mainly related to the
activation method and the treatment parameters. Chemical activation by alkaline fusion is a
promising method allowing preparation of one-part geopolymer materials, an alternative class of
geopolymeric binders. However, the resulting alkaline-fused geopolymer products are vulnerable
to attack by excessive alkalis.