Alkali-activated Materials: Environmental Preliminary Assessment for U.S. Roadway Applications

The capital investment in the U.S. for construction and maintenance of the infrastructure road network is on the order of $100 billion/year. On average, investments in Organization for Economic Cooperation and Development (OECD) countries are likely to stabilize, while China will face an exponential growth of investments for new infrastructures driven by the development of metropolitan cities. Continued “business-as-usual” practice for portland and asphalt cement concrete pavement construction ignores the increasing warning calls for the identification of more sustainable and less energy intensive paving materials. It is therefore important to explore alternative pavement materials, which may have benefits in terms of environmental impact and durability performance over the current technology. Alkali activated materials concrete (AAM) exhibit these beneficial characteristics. AAM compositions have been studied with growing interest during the last three decades, and showing 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 these material is closely dependent on: 1) the alkali activating solution used to activate the raw material 2) the origin of the raw material. Specifically, the impact of the transport for both of these components has an impact quantifiable around 10% of its global warming potential. Hence, to increase the adoption of AAM for civil applications such as pavements, it is fundamental to analyze the existing literature to clarify the link between environmental and mechanical performance, identifying opportunities for applications that are tailored to the local availability of raw material, reducing transport environmental costs.