Author: Arjun Singh Virdi
Singh Virdi, Arjun, 2024 Transforming Sustainability: Using Delithiated Beta Spodumene in Geopolymer production, Flinders University, College of Science and Engineering
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Geopolymer presents itself as a promising substitute for conventional binder, such as Portland cement, which, although widely used worldwide, is considered a non-environmentally friendly and sustainable substance due to carbon dioxide emission. Reducing CO2 emissions can be achieved by substituting Portland cement with industrial by-products like Fly ash (FA), Ground granulated blast-furnace slag (GGBS) and Delithiated beta spodumene (DBS) to develop a geopolymer mix which is more sustainable and eco-friendlier. Geopolymer exhibits pozzolanic properties like traditional cement and have extraordinary mechanical properties, when mixed with alkaline activator solution in an optimum ratio. This thesis is a study of the influence of DBS when used as FA replacement in varying ratio of 25%, 50% and 75% having consistent amount of GGBS 25%. The other parameters like binder to sand ratio, liquid to binder ratio and sodium silicate to sodium hydroxide ratio is kept constant for all mixes. Achieving optimal strength properties in geopolymer mixes requires accurate proportions of materials. In this study, the geopolymer mix have a sand-to-binder ratio of 2, a sodium silicate-to-sodium hydroxide ratio of 1.75, and a liquid-to-binder ratio of 0.5 to analyse compressive and flexural strengths. The examined properties of DBS based geopolymer include workability, compressive strength, flexural strength, and water absorption percentage. Results indicate that increasing the water content generally enhances workability, while reducing FA content improves flow table spread in workability test. The ideal sodium hydroxide solution molarity was determined to be
12 M. Four mix designs were tested, with the mix containing 75% DBS achieving compressive strength values of 25.46 MPa at 7 days and 39.08 MPa at 28 days. A significant increase in flexural strength was observed when 75% of fly ash was replaced with DBS, reaching 3.324 MPa at 7 days and 3.73 MPa at 28 days. The study highlights that increasing DBS content from 0% to 75% significantly enhances both
compressive and flexural strength of geopolymers. The water absorption percentage at 7 and 28 days is around 11% and all the mix designs have around the same percentage of water absorption.
Keywords: Delithiated Beta Spodumene, DBS, Geopolymer, Compressive strength, Flexural strength, water absorption, Fly ash, GGBS, Sodium silicate, Sodium hydroxide, workability, Lithium residue
Subject: Engineering thesis
Thesis type: Masters
Completed: 2024
School: College of Science and Engineering
Supervisor: Aliakbar Gholampour