Geopolymere

Geopolymer refers to inorganic polymeric binders formed by the polycondensation of aluminosilicate materials with alkaline activators. The resulting three-dimensional network consists of Si–O–Al linkages balanced by alkali cations, yielding a cementitious material that can set and harden at room temperature or with modest heating. Common precursors include fly ash, metakaolin, slag, and natural clays; activators are typically sodium or potassium hydroxide and silicate solutions.

The concept arose from research on alkali-activated materials in the late 20th century. The term geopolymer was popularized by Joseph Davidovits in the 1970s and 1980s, with ongoing work on low-temperature processing and sustainable binders.

In alkaline media, aluminosilicate feedstocks dissolve and re-polymerize into a cross-linked gel and a hardened network. The Si/Al ratio influences properties. Curing can be ambient or elevated-temperature, depending on formulation and activator. Materials can form concretes, mortars, or refractory components.

Geopolymers display high early strength, superior fire and chemical resistance, and potential lower embodied energy than Portland cement when based on industrial by-products. Common applications include structural concretes, refractory linings, and waste immobilization. Limitations include feedstock variability, limited long-term data, standardization challenges, and costs or handling considerations for alkaline activators.