Geopolymers

Geopolymer is a term covering a class of synthetic Soil cements ^{[1] [2]}

Research

Much of the drive behind research is to investigate the development of geopolymers as a potential large-scale replacement for carbon dioxide emissions, greater chemical and thermal resistance and better mechanical properties at both atmospheric and extreme conditions.

Production

Geopolymers are generally formed by reaction of an aluminosilicate powder with an alkaline silicate solution at roughly ambient conditions. fly ash from coal. Most studies have been carried out using natural or industrial waste sources of metakaolin and other aluminosilicates.

Theory

The majority of the Earth’s crust is made up of Si-Al compounds. Davidovits proposed in 1978 that a single aluminium and zeolitic materials but exist as amorphous solids, rather than having a crystalline microstructure.

Structure

The chemical reaction that takes place to form geopolymers follows a multi-step process:

1. Dissolution of Si and Al atoms from the source material due to hydroxide ions in solution,
2. Reorientation of precursor ions in solution, and
3. Setting via polycondensation reactions into an inorganic polymer.

The inorganic polymer network is in general a highly-coordinated 3-dimensional aluminosilicate cations.

References