Project Status: Complete
Project Participants: Alcoa, Curtin University of Technology
Project Leader: Arie van Riessen (Curtin University of Technology)
CSRP Participants, Curtin and Alcoa, have successfully produced a number of geopolymer samples using a combination of Bayer liquor and fly ash or silica fume as part of the "Geopolymer Concrete from Regional Waste Streams" (4B1 Extension) project. Since November 2007, the project has successfully converted the geopolymer paste to mortar by adding various sands. Also lime addition has been shown to enable the geopolymer to cure at ambient temperatures with a marked improvement in strength.
Results from all stages of the project have been extremely promising. However further fundamental research is required to measure the Bayer geopolymer aluminium and silicon bonding, to enable confirmation that the structure is in fact consistent with traditional aluminium-silicon inorganic polymers. This project aimed to better understand the Bayer liquor samples and enable an understanding of the influence of Bayer liquor impurities upon the geopolymer formation mechanism. Bayer geopolymer were compared and assessed to standard geopolymer formation and structure.
The project had two distinct paths, namely fundamental science and manufacture of geopolymer from Bayer liquor. The fundamental science work included x-ray diffraction (XRD), pair distribution function (PDF), and nuclear magnetic resonance analysis (NMR) of pure- and fly ash- based geopolymers.
This research has provided an increased understanding of the formation and identification of geopolymers and is helping inform the applied research using industry residues. The XRD work made a breakthrough in the use of a calibration curve that enables the ratio of the precursor and geopolymer to be determined directly. A journal paper was written to report this development.
The applied work concentrated on developing consistent sample properties from different batches of liquor. Replacement materials for silica fume were also investigated, as well as different fly ashes so that silicon/aluminium ratios can be optimised. Production of geopolymer from 100 percent replacement of sodium hydroxide with Bayer liquor provided consistent and predictable results.
Further work on Bayer liquor geopolymer continues beyond the term of CSRP and will be funded by the industry sponsor.