Concrete is the second most consumed material in the world after water, used most widely in the construction industry. The materials required for concrete - sand, gravel & water are often locally available and are relatively inexpensive. Cement is the glue that binds these aggregates together to form concrete – a relatively small amount of cement (about 14%) and Reinforcing steel (about 2-4%) are required for production of reinforced concrete.
Clinker is the primary component of cement, a dark grey nodular material made by heating ground limestone and clay at a temperature of about 1400 °C - 1500 °C. The nodules are ground up to a fine powder to produce cement, with a small amount of gypsum added to control the setting properties. Carbon emissions from the manufacture of clinker are second only to that of emissions from fossil fuels, and clinker is responsible for a significant proportion of Australia’s total greenhouse gas emissions.
In order to reduce the environmental impact of the concrete industry, Supplementary Cementitious Materials (SCMs) such as fly ash and Ground Granulated Blast-Furnace Slag (GGBFS) have been intensively used to partially replace clinker in concrete. Currently, fly ash, a widely available by-product from coal fired power stations, is the most common SCM used in Australia.
However, to address the effects of climate change, Australia has also opted to transition from fossil fuels to renewables. The shift away from coal burning to renewable energy is expected to lead to a drastic reduction in local fly ash production. The importation of millions of tonnes of fly ash every year could put the financial sustainability of the Australian concrete industry at risk.
There is an urgent need, therefore, to develop an alternative SCM available locally in suitable quantities to replace fly ash in the future. Calcined clay is a potential alternative SCM and large quantities of these clays are available in Australia. The »Ê¹Ú²ÊƱ research project led by A/Professor Arnaud Castel aims at investigating the viability of this new low carbon concrete technology. There is some sense of urgency about the project. To preserve the sustainable performance of the entire construction industry, this new concrete technology must be ready and adopted by the industry before Australia runs out of fly ash. Castel’s project will investigate the reactivity of calcined clay as a SCM in Australia. In collaboration with Dr Rackel San Nicolas at the University of Melbourne and Dr Taehwan Kim (»Ê¹Ú²ÊƱ Sydney), clays across Australia are being collected, characterised and calcined with the aim of identifying calcined clay