Geopolymer Composite Materials from Mining and Agricultural Residues for Engineering Applications: Red Mud and Rice Husk Ash | Chapter 7 | Current Research on Geography, Earth Science and Environment Vol. 3

 

The transformation of raw materials into finished products generates residues and waste, whose management has become an environmental concern. With industrialisation and increasing material complexity, human activities have led to the exponential generation of waste. The more diverse and synthetic the materials involved, the more challenging it becomes to manage waste in ways that fulfil the dual objectives of protecting human health and the environment while conserving natural resources. In the Bayer process, the reaction of bauxite with sodium hydroxide to produce alumina results in the generation of red mud (RM), a highly alkaline waste that occupies land and poses environmental risks. In Guinea, rice is a staple food, and its processing produces large quantities of rice husk (RH), which also presents disposal challenges. RH contains about 20% silica, which becomes approximately 90% silica after combustion, forming rice husk ash (RHA) — a valuable material for various applications. Geopolymer technology offers a sustainable route for the valorisation of industrial residues. This study aimed to develop and analyse geopolymer composite materials using red mud and rice husk ash as alternatives to conventional construction materials. In this study, a composite geopolymer (GP) was synthesised using RM from a local alumina plant, RH from a local rice mill in Guinea, and water glass solution (WGS). For mechanical and microstructural characterisation, the geopolymer specimens were categorised into three main groups—GPA, GPB, and GPC—based on varying RM and RHA ratios while keeping the water glass solution (WGS) constant at 15%. Various mix ratios of RM, RHA, and WGS were tested. The resulting specimens were evaluated for compressive strength at different curing temperatures. Microstructural characterisation was conducted using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The results revealed that the final product is predominantly composed of amorphous geopolymeric phases and that higher temperatures enhance the compressive strength of the material. The XRD of RM is characterised by the presence of sharp peaks mainly caused by hematite (Fe₂O₃), gibbsite (Al(OH)₃), akdalaite (4Al₂O₃·H₂O), lepidocrocite (FeO(OH)), and calcite (CaCO₃). There are no broad humps in the pattern; hence, amorphous phases are not present in large quantities. The greatest value of compressive strength was developed by the GPB1 specimen exhibited a strength:  36,31 MPa at ambient temperature and 66,97 MPa at 1000°C. Through geopolymerization, RM and RH are not stored in piles or dumped into nature; this is a considerable achievement for the circular economy and the zero waste principle.

 

 

Author(s) Details

D. Sidibé
Higher Institute of Mines and Geology of Boké, ISMGB, Guinea.

 

D. Keita
Higher Institute of Mines and Geology of Boké, ISMGB, Guinea.

 

A. A. Konaté
Higher Institute of Mines and Geology of Boké, ISMGB, Guinea.

 

O. B. Kaba
Higher Institute of Mines and Geology of Boké, ISMGB, Guinea.

 

M. Cissé
Higher Institute of Mines and Geology of Boké, ISMGB, Guinea.

 

S. Traoré
Polytechnic Institute, University of Conakry, UGANC, Guinea.

 

Please see the book here :- https://doi.org/10.9734/bpi/crgese/v3/6247