Chemical resistance of geopolymer concrete against H2SO4 & NaOH

Tomkins, Brock William (2011) Chemical resistance of geopolymer concrete against H2SO4 & NaOH. [USQ Project] (Unpublished)

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Abstract

The purpose of this project is to develop innovative environmental green concretes and study their performance, particularly the chemical resistance. The concretes under investigation include fly-ash based geopolymer concrete (FAGC) and red-mud based geopolymer concrete (RMGC). The chemical resistance tests involve sodium hydroxide and sulphuric acid at 20 degrees C and 90 degrees C. To understand the relative significance of these results, they are contrast alongside the performance of ordinary Portland cement concrete (OPC) in the same conditions. Geopolymer concrete is the name given to concrete where the binder is entirely replaced by an inorganic polymer formed between a strong alkaline solution and an aluminosilicate source. The ratio and quantity of alkaline solution used can affect – amongst other factors – the concrete strength and curing time. Aluminosilicate sources include but are not limited to red-mud, fly-ash, blast furnace slag and kaolin. The variability of geopolymer binders and activators increase the difficulty of manufacturing a homogenous and universal geopolymer concrete standard. Currently, geopolymer concrete exhibits as good as, and in some areas superior engineering properties to normal concrete. Carbon emissions can be significantly reduced by using aluminosilicate geopolymer binders instead of Portland cement (which releases 1 t of CO2 per tonne of production). Compared to Portland cement, fly-ash based geopolymer concrete can reduce carbon emissions by 80% which has the potential to reduce global emissions by approximately 2.1 billion tonnes a year. This is equivalent to taking two thirds of global traffic off the roads each year. In this project OPC, FAGC and RMGC samples were cast in 200x100mm cylindrical moulds. After these samples cured for a minimum of 14 days, chemical testing began. The samples were submerged for 7, 14, 28 and 56 days, sulphur capped and compression tested. Results comprised the analysis of testing data, macro analysis and microscopy. Results indicated OPC experienced some strength deterioration in both an acid environment (-24.9 to -25.6%) and an alkaline environment (-2.2 to -13.3%). FAGC was found to have better acid resistance (+3.8 to -17.6%) and even experienced strength enhancement in sodium hydroxide (+29.1 to +55.7%). Interestingly, RMGC exhibited a strength increase of 52.4% in sulphuric acid while also displaying strength enhancement of +50.5% in sodium hydroxide. This performance suggests that FAGC and RMGC are both suitable replacements for the existing bunding slab at QAL.


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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Depositing User: ePrints Administrator
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Agricultural, Civil and Environmental Engineering
Date Deposited: 21 May 2012 05:28
Last Modified: 21 May 2012 05:28
Uncontrolled Keywords: chemical resistance; geopolymer concrete; sodium hydroxide; sulphuric acid
Fields of Research (FOR2008): 09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
09 Engineering > 0905 Civil Engineering > 090506 Structural Engineering
09 Engineering > 0912 Materials Engineering > 091202 Composite and Hybrid Materials
URI: http://eprints.usq.edu.au/id/eprint/21302

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