The strength of geopolymers based on red mud and fly ash

Abstract

Alkali activated materials (geopolymers) are relatively new materials, thanks to their good mechanical, physical, thermal properties and at the same time environmental friendliness, they could be widely adopted in different fields. The experiments, described in this article, are focused on the investigation of compressive strength of alkali activated materials based on fly ash and red mud. For the following experiments were prepared five series of samples with different ratio of red mud to fly ash. All the samples had the form of cubes with dimensions 30mmx30mmx30mm. The tests on compressive strength were conducted in 7, 28 and 56 days after final heat treatment. The test showed that the highest strength had the samples with the smallest amount of red mud (5%). In 56 days it was 29 MPa. Meanwhile the samples with the biggest amount of red mud (50%) were not even tested because of samples cracking during heat treatment.