Examining the viability of geopolymer concrete: carbon dioxide emissions and key attributes

Abstract

Concrete underpins ancient and modern engineered cities, and combined with steel is a key material used in modern construction. Architects have the capacity to influence the uptake of energy efficient systems used in construction. The 3.3 billion tonne p.a. Portland cement industry generates almost 10% of global anthropogenic carbon dioxide emissions. With the latent and rapid industrialisation of China and India and other developing countries, cement demand is projected to double to 6 billion tonnes p.a. by 2050. An alternative technology, geopolymer, uses an alkali activator which combines high portions of industrial by-product to form an alternative binder for concrete. There is much debate in industry regarding the environmental and structural performance of geopolymers. This thesis re-evaluates the carbon dioxide emissions associated with geopolymers, and examines key material attributes affecting viability. The appropriate manufacturing path for the alkali activator can achieve a reduction in carbon dioxide emissions of 59 - 92% compared to Portland cement. At present there is some limited commercial uptake of geopolymer concrete in select markets such as Russia, Australia and China. However, there is no wide global-scale utilisation. Barriers and opportunities for uptake are reviewed in this thesis. A saving of 600 billion tonnes of carbon dioxide emissions over the next four decades will be needed to achieve the stabilisation of greenhouse gas emissions concentrations between 450 and 550 parts per million of carbon dioxide emissions equivalent. With this mounting challenge, combined with the activation of global carbon markets predicted to be worth in excess of AUD 1 trillion within 5-10 years, there is likely to be growing interest in cement sector technologies which can deliver major reductions in carbon dioxide emissions.