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Concrete In Australia : September 2013
32 Concrete in Australia Vol 39 No 3 particular application, performance and cost are key factors. Materials with enhanced performance but higher cost can benefit from information on how the market values that performance (Maine et al, 10). In the case of geopolymer concrete, costs are predicted to be higher than conventional concrete under current availability (McLellan, 8). erefore, overcoming the costs in terms of performance requires analysis of the importance of superior properties (e.g. fire or acid resistance) and greenhouse gas reduction to the construction industry and greater dissemination of potential benefits to end users. e TRB research agenda (TRB, 11) proposed actions to address specific barriers to implementation of new and innovative materials and technologies in the transportation industry. Many of these actions are similar to those recommended for geopolymer concrete and include outreach to raise awareness, education and workforce training, development of new or modified material, design and construction standards and specifications, development of performance-based standards and specifications and dissemination of best practices. 6.1 Polymer concrete Two examples of new materials development in the concrete field are polymer concrete and fibre reinforced polymer (FRP) reinforcement. e pathways to use and acceptance of these materials are relevant. Polymer concrete, polymer impregnated concrete and polymer modified concrete were the subject of extensive research and development at the US Department of Energy s Brookhaven National Laboratory (BNL) from the mid-1960s until the late 1990s. is work, together with research at other organisations, resulted in the development of commercial products for numerous applications. e ability to formulate polymer concrete from different resins resulted in a wide range of properties and versatility. BNL s work on polymer concrete comprised: • laboratory preparation and thorough testing of different formulations for engineering, physical and durability properties • evaluation of properties and identification of potential applications • independent economic assessment • development of specific materials for a particular need • scale-up and field demonstrations in collaboration with regulatory agencies, industry partners and end-users • monitoring of field demonstrations and evaluation of material performance • development of user guidelines and specifications • testing to meet requirements of specific codes and standards in order to gain approval • technology transfer through publications, conference presentations, field demonstrations, active membership of technical committees, support and training • technology transfer to commercial applicators • contribution to ACI Committee 548 and development of ACI guidelines and specifications for polymer and polymer modified concrete. e primary focus of research and development of polymer concrete was applications where superior performance compared with Portland cement concrete could be readily achieved. Examples include durability in aggressive environments, high temperature performance, rapid setting, high strength, adhesion, low permeability, wear resistance, versatility and aesthetics. Owing to economics, polymer concrete cannot realistically replace Portland cement concrete in conventional construction. However, there is significant demand for polymer concrete in precast applications, overlays for concrete protection, concrete repair, decorative floors and other specialised uses where performance benefits or life-cycle costs outweigh initial cost. For geopolymer concrete, reduced greenhouse gas emissions and improved performance in particular applications are the key benefits. Unlike polymer concrete, geopolymer concrete has the potential for greater volume use, in addition to niche applications. e approach used by BNL, other research institutions, government organisations and private industry in the development of polymer concrete shows that considerable effort and resources over a sustained period of time are required to take a material from the laboratory to widespread use and acceptance. 6.2 Fibre reinforced polymer reinforcement Another example of introduction of a new material to an established market is the use of fibre reinforced polymer (FRP) reinforcement as an alternative to steel. e use of FRP reinforcement in concrete is of growing interest primarily due to its resistance to corrosion and damage associated with steel reinforcement, especially in aggressive environments. Owing to the relatively short track record of FRP reinforcement in concrete compared with conventional steel, questions arise as to its performance and durability. Extensive research on the performance of FRP has been conducted including accelerated laboratory tests and monitored field demonstrations to address raised concerns. Key to greater acceptance of FRP reinforcement has been publication of research results, devoted conference streams, field demonstrations involving collaboration between research institutions and transportation agencies, and production of informative reports, specifications and design guidelines, particularly from ACI Committee 440. e example of how FRP reinforcement has overcome barriers to acceptance highlights the necessity for targeted research, engagement with regulatory agencies and development of design standards, specifications and guidelines. Similar actions, particularly on production of standards, are required for greater adoption of geopolymer concrete. 7.0 CONCLUSIONS Alternative, low CO2 concrete materials offer potential benefits in reducing the greenhouse gas emissions associated with conventional concrete based on Portland cement. However, conventional concrete is a long-established material entrenched in the construction industry and the use of alternatives such as geopolymers faces many barriers. ese barriers are similar to those encountered for other alternative or new materials in infrastructure applications. e barriers have been analysed to determine pathways so that geopolymer concrete can be used in large volumes with greater confidence and less risk.