Application of diatomite as a substitute for fly ash in foamed geopolymers

Abstract

In recent years, new climate targets in EU have led to a growing demand for construction materials with a lower carbon footprint. This implies a demand for research on materials with comparable properties and reduced CO2 emission to replace those currently in use. Geopolymers belong to the group of alkali-activated aluminosilicates, whose advantages include high compressive strength and high corrosion resistance. Examples of aluminosilicate materials used to produce geopolymers are fly ash, metakaolin or volcanic tuff. Recently, there have also been papers discussing the use of diatomite as a replacement for metakaolin in geopolymer materials. The purpose of this work is to investigate the use of diatomite as a fly ash replacement in the production of foamed geopolymers. For this purpose, fly ash based geopolymer samples with different amounts of diatomite (5%, 10%, 50%) were foamed using hydrogen peroxide as a foaming agent. Then, to observe the microstructure of the produced samples, they were subjected to scanning microscope observations. Compressive strength tests according to EN 12390-3 standard were carried out to check the strength properties after 30 days of curing. In addition, the thermal conductivity coefficients of the samples were investigated to better determine their potential industrial application. The expected result is a change in strength and thermal properties with increasing diatomite content.