Synthesis and characterization of geopolymer material derived from gold mine tailings with bismuth oxide nanomaterial for electromagnetic interference shielding and high thermal application

• Main Author: Maestre, Christian V.
• Format: text
• Language: English
• Published: Animo Repository 2022
• Subjects: Gold mines and mining; Bismuth trioxide; Nanoparticles; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etdm_physics/7
• Institution: De La Salle University

Industrial wastes such as gold mine tailings, coal fly ash and sugar cane bagasse have been repurposed via geopolymerization to produce geopolymer (GP) concrete. GP have poor electromagnetic interference shielding efficiency (EMI-SE) compared to conventional concrete, due to this, a conductive filler must be incorporated in its matrix to enhance its attenuating properties. For this study, bismuth oxide (Bi2O3) nanomaterial was utilized as the additive filler. The influence of Bi2O3 on the EMI-SE of GP in the microwave range were studied. Furthermore, the effect of Bi2O3 to the thermal properties of GP were also determined. Morphological characteristics was conducted using a scanning electron microscopy coupled with elemental dispersive x-ray for elemental mapping. The reaction mechanism and minerals present in GP were investigated by Fourier transform infrared spectroscopy and x-ray diffraction analysis, respectively. Results of the analysis shows that Bi2O3 were embedded in the matrix of GP and no new aluminu-phyllosilicate minerals were formed after geopolymerization. This indicates that some minerals did not participate in the polymerization and acted only as internal filler in the matrix of GP. Compressive strength test shows that the synthesized GP were more than 20 MPa, with neat GP reaching the maximum strength. Moreover, the shielding efficiency of neat geopolymer (without Bi2O3) was 21.2 dB in the frequency range from 20-4500 MHz. This value indicates that GP alone can attenuate 99% of EMI radiation. Furthermore, addition of 5%, 10% and 15% Bi2O3 improves the shielding efficiency of GP by 4-10%, with 5% BiNP shown to be the optimum ratio. Lastly, addition of Bi2O3 reduces the evident weight loss of GP. Based on the cost analysis of the synthesized geopolymer over the conventional concrete, this study clearly shows that GP incorporated with Bi2O3 can be recommended for small-scale construction and small residential building.