A Systematic Bottom-up Approach for Decarbonization of Concrete

School of Engineering, Macquarie University, Sydney, Australia

 Abstract: Climate change is one of the biggest problems the world is facing. The Paris agreement (2015) commits signatory nations to limit global warming to well below 2^oC, preferably 1.5^oC, compared to pre-industrial levels. In Australia, the construction industry contributes around 18% of total greenhouse gas emissions. Australia consumes, approximately 29 million m³ of concrete each year. The embodied carbon of structural concrete typically ranges from 230 to 615 kg CO2e/m³. On this basis, total embodied carbon associated with concrete in Australia is estimated as 12 Mt CO2e. Therefore, decarbonization of concrete is a key component to Net Zero 2050 strategy across the construction industry. A typical concrete mix consists of 12% Portland cement material, 77% fine & coarse aggregates, 3% supplementary Cementitious material (SCM) and 8% admixtures/ water. Portland cement is the highest embodied carbon material (approximately 905 kg CO2e/t) in a concrete mix and is responsible for approximately 90% of concrete’s footprint. Most concrete decarbonization strategies propose partial or full replacement of Portland cement to reduce the carbon footprint of concrete. This paper presents an overview of a systematic analysis of various concrete decarbonization technologies being adopted worldwide. The study shows that none of the technologies can achieve the net zero goal on a standalone basis. It is recommended that a custom strategy combining more than one technology will have to be adopted to suit the circumstances.