Life Cycle Assessment of alkali activated materials for pavement applications: preliminary investigation of precursors

Abstract

According to the OECD database, investments in road networks amounted to €170 billion in 2018, with current practice focused towards portland and asphalt cement concrete pavement. Identifying more sustainable and less energy intensive paving materials is crucial for the expected exponential growth of developing countries. Alkali activated materials concrete (AAM) have been studied with growing interest during the last three decades. AAM show promising results in terms of mechanical performance, while also having a global warming potential impact 30‐80% less than that of portland cement concrete. The global warming potential of AAM is closely dependent on the: 1) activating solution used to activate the precursor and 2) the geographical location of the precursor. Specifically, the impact of the transport for both of these components is ~10% of its global warming potential. This study correlates precursor availability, based on global trends in power generation and steel manufacture as well as geological variations, with two key performance metrics: CO2 intensity and compressive strength. Results indicates that AAM production in the future should utilize MK or other sources of that are locally available in states where the coal industry is being phased out, while in Asian markets, AAM production will likely be based on fly ash and slags. Additionally, AAM display a lower CO2 intensity when compared to traditional binders, while providing the required compressive strength for pavement applications (30 MPa). Hence, to increase the adoption of AAM for pavements, it is fundamental to identify opportunities for applications that are tailored to the local availability of raw material.