One-Part Mix Geopolymer Concrete with Waste Glass Aggregates
Ailar Hajimohammadi1, Taehwan Kim2, Stephen Foster3
1 Associate Professor, School of Civil and Environmental Engineering, University of New South Wales 2 Senior Lecturer, School of Civil and Environmental Engineering, University of New South Wales
3 Professor, School of Civil and Environmental Engineering, University of New South Wales
According to a Cement and Concrete Association (CCAA) report 55 percent of the carbon emissions from the cement and concrete industry in Australia originates from cement production. A unique one-part mix, low-carbon geopolymer concrete (GPC) conforming to a modified project-specific TfNSW R53 specification, was developed at the UNSW laboratory and trialled by our industry partners at the WestConnex 3B Rozelle Interchange Project. A One-part mix geopolymer design is a solid mixture of dry materials which will only react after adding water (very similar to Portland cement-based concrete). This one-part concrete mix solution also improves the workers safety as there is no need to handle hazardous chemicals likes alkali activators on site and concrete produced is of consistent quality from a normal concrete batching plant and transported to site. In the first trial on 18 Nov 2021, 5 m3 of GPC was produced to install a footpath slab. In the next phase, the sand portion of the GPC was partially replaced by the recycled glass as fine aggregate, and the concrete mix was optimised to compensate for the strength loss and to eliminate the possibility of expansions from the alkali-aggregate reaction (AAR). In the second trial on 6 Sep 2022, 2.5 m3 of GPC was produced to install two sections of the kerb. The GPC performed satisfactorily mechanically without risk of flash setting or durability concerns towards the target specifications. The field concrete closely follows the strength development of the lab GPC and is expected to conform to specifications like the lab concrete. Data gathered from the lab trials, the observations made, and knowledge gathered in the field trial will be utilised to further optimise the mix, particularly in ensuring good workability for future pours. The GPC development involved material characterisation, theoretical understanding, rigorous testing, and optimisation towards conforming to R53 specifications. We understand that on the conclusion of research and field trials which will provide better confidence on mix behaviour and performance, Transport for NSW have definitive plans to promote sustainability and reduce carbon emissions with the inclusion of GPC in general concrete works and pavements.
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