Design of a high-shear geopolymer concrete mixer

Brown, Steven (2011) Design of a high-shear geopolymer concrete mixer. [USQ Project] (Unpublished)

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Abstract

Concrete is a well known and understood product used extensively in the building and construction industry however there are ecological drawbacks associated with its use. Geopolymer concrete has been presented as a comparatively environmentally friendly alternative; replacing traditional aggregate with an alumino-silicate material (i.e. fly-ash) and the traditional OPC (ordinary Portland cement) binder with an alkaline solution. Preliminary research performed by HALOK identified deficiencies in the existing mixing techniques and suggested that a high-shear mixer may significantly improve the mechanical strength characteristics of aerated geopolymer concrete. This study involves the development of a conceptual high-shear mixer suitable for the preparation of aerated geopolymer concrete samples. ANSYS-CFX computational fluid dynamics (CFD) software has been used in conjunction with Solidworks 3D modelling software to model the behaviour of the tradition „paddle mixer‟ and proposed high-shear mixer, to permit a comparison between the two, and ultimately verify the validity of the concept. The conceptual mixer utilises a rotor-stator arrangement to impart the required shear into the fluid and develop sufficient pressure to promote recirculation of the fluid. Also key to the performance of the mixer is a fly-ash injection system, which is intended to permit greater control over the water/solid ratio of the paste, without compromising workability. Modelling techniques employed to conduct the steady state analyses include multiple frame of reference and multiphase analysis. Variables used in assessing the suitability of the high-shear mixer include velocity, pressure and shear strain rate. Results from the CFD analysis conducted indicate a significant increase in average shear strain rate compared to the traditional „paddle‟ style mixer. This is expected to result the mixer being able to produce a more homogenous geopolymer paste, ultimately resulting in an increase in strength of aerated geopolymer concrete.


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Item Type: USQ Project
Refereed: No
Item Status: Live Archive
Depositing User: epEditor USQ
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Mechanical and Mechatronic Engineering
Date Deposited: 10 Sep 2012 03:27
Last Modified: 03 Jul 2013 01:28
Uncontrolled Keywords: high-shear ; geopolymer concrete
Fields of Research (FOR2008): 09 Engineering > 0905 Civil Engineering > 090506 Structural Engineering
09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
09 Engineering > 0912 Materials Engineering > 091202 Composite and Hybrid Materials
URI: http://eprints.usq.edu.au/id/eprint/21891

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