Article

SCM's potential to lower Australia's greenhouse gas emissions profile

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Abstract

Under the Kyoto Accounting rules, Australia's National Greenhouse Gas Inventory Report emissions for 2002 was 550.1 Mt carbon dioxide equivalent (CO 2 -e) being a net increase of 1.3% on the 1990 level. This increase is largely attributed to the stationary energy, transport and industrial process sectors, offset with significant reductions from reduced land clearing. For the construction sector additional mitigation strategies could be employed to further reduce Australia's net CO 2 -e emissions. For example through increased use of mineral resources like coal combustion products such as; fly ash, iron blast furnace slag and amorphous silica, or commonly referred to as supplementary cementitious materials (SCM's), used with Portland cement in the manufacture of concrete. For Australia, the manufacture and delivery of one tonne of cement results in the emission of approximately 0.82 tonne of CO 2 -e or 6.5 Mt of CO 2 -e emitted for total cement sales in 2002. Using data collected from companies processing fly ash and iron blast furnace slag, life cycle analyses were conducted to demonstrate the reduced embodied energy and resultant CO 2 -e signature for one cubic meter of concrete containing various combinations of fly ash and iron blast furnace slag. From the resultant data and analysis a simple CO 2 -e estimator has been developed to assist architects, designers and consulting engineers to specify eco-friendly structures. For the construction of a domestic dwelling (four bedroom home) using approximately 130 cubic meters (m3) of 25 MPa concrete containing binder ratios of 35% Portland cement and 65% ground granulated blast furnace slag cement, the total savings in CO 2 -e emissions was 17.03 tonnes, or equivalent to emissions from a four-cylinder car for 5.68 years. The paper will briefly discuss Australia's current National Greenhouse Gas Inventory Report in the context of how increased use of SCM's in the construction sector can further lower greenhouse gas emissions, whilst still delivering improved durability performance.

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... However, the capture, milling and grinding, drying and transportation of FA causes energy consumption. Based on the literature, the reported values of CO 2 -eq/kg for FA was in the range of 0.007 to 0.027 kg (Heidrich et al., 2005;Phetchuay et al., 2016). Moreover, as RM is a waste by-product, and there were not any consuming energy activities for it in this study, the CO 2 -eq of RM is related to its transportation. ...
... Coarse aggregates 0.0408 (Turner & Collins, 2013) k gC O 2 -eq/kg 0.019 $/kg material Fine aggregates 0.0139 (Turner & Collins, 2013) k gC O 2 -eq/kg 0.012 $/kg material Fly ash (F-type) 0.027 (Heidrich et al., 2005) k gC O 2 -eq/kg 0.045 $/kg material Red mud 0.00518 (Heidrich et al., 2005) k gC O 2 -eq/kg 0 $/kg material Crumb rubber -0.103 (Farina et al., 2017) k gC O 2 -eq/kg 0.05 $/kg material Chipped rubber 0.0195 (Farina et al., 2017) k gC O 2 -eq/kg 0.031 $/kg material Sodium hydroxide 1.915 (Duxson et al., 2007) k gC O 2 -eq/kg 0.2 $/kg material Sodium silicate 1.514 (Duxson et al., 2007) k gC O 2 -eq/kg 0.4 $/kg material RM30FGC-CR90 with the highest amounts of RM and chipped rubber were determined to be the most environmentally friendly and economical specimen among the others, but its mechanical properties were the lowest. Therefore, the necessity of multicriteria optimization was sensed among these conflicting responses to establish a trade-off. ...
... Coarse aggregates 0.0408 (Turner & Collins, 2013) k gC O 2 -eq/kg 0.019 $/kg material Fine aggregates 0.0139 (Turner & Collins, 2013) k gC O 2 -eq/kg 0.012 $/kg material Fly ash (F-type) 0.027 (Heidrich et al., 2005) k gC O 2 -eq/kg 0.045 $/kg material Red mud 0.00518 (Heidrich et al., 2005) k gC O 2 -eq/kg 0 $/kg material Crumb rubber -0.103 (Farina et al., 2017) k gC O 2 -eq/kg 0.05 $/kg material Chipped rubber 0.0195 (Farina et al., 2017) k gC O 2 -eq/kg 0.031 $/kg material Sodium hydroxide 1.915 (Duxson et al., 2007) k gC O 2 -eq/kg 0.2 $/kg material Sodium silicate 1.514 (Duxson et al., 2007) k gC O 2 -eq/kg 0.4 $/kg material RM30FGC-CR90 with the highest amounts of RM and chipped rubber were determined to be the most environmentally friendly and economical specimen among the others, but its mechanical properties were the lowest. Therefore, the necessity of multicriteria optimization was sensed among these conflicting responses to establish a trade-off. ...
... (1) Where is the dosage of raw materials (kg/m 3 ), i refers to cement, fly ash, fine aggregate, coarse aggregate, water and superplasticiser, and is the emission factor of different raw material (kg CO 2 -e/kg), they are 0.92 [5] , 0.027 [6] , 0.0408 [7] , 0.0139 [5] , 0.000213 [8] and 0.72 [9] , respectively. ...
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Chapter
Full-text available
This chapter addresses potential alternatives for base raw materials as well as potential solutions for sustainability in mass concrete. Issues like material selection and environment, material properties and mix design, durability, carbon footprint and life cycle analysis (LCA) of mass concretes are reviewed. The focus is put on recycling. Besides the use of conventional SCMs, non-conventional biomass pozzolans, based on combustion of renewable source of energy, like woody ashes, sugarcane bagasse ash and rice husk ash are covered. The synergic use of several mineral SCMs as a partial substituent of Portland cement is addressed. Furthermore, reuse of aggregates from construction–demolition waste as well as natural fiber alternatives to steel and synthetic reinforcements is discussed in detail. Materials selections and the consequence of it on the properties that affect the mix design and material properties specifically related to durability are summarized. An introduction on life cycle assessment (LCA) is given with its pros and cons, followed by its review on different mass concrete mixtures, separately addressing LCA of binders, aggregates, concretes and reinforced concrete structures with placement technologies. Limitations and further research directions are highlighted.
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