Pulverized coal fly ash and ground granulated-based furnace slag are used in a vast majority of Portland cement concrete mixtures that form the Nation's highway infrastructure. They address sustainability challenges and ensure the cost competitiveness, high performance, and durability of concrete. Recently, there have been significant supply shortages of both materials, and their future economic availability remains uncertain. It is estimated that by the year 2030, the supply of ASTM C618-compliant fly ash in the United States will remain at 14 million tons, while the demand will exceed 35 million tons. A recent inventory and analysis by the United Nations Sustainable Buildings and Climate Initiative revealed that only calcined clays, natural pozzolans, and limestone resources are cost competitve and abundant at levels sufficient to displace Portland cement and compensate for the supply gap of traditional supplementary cementitious materials. However, insufficient knowledge of their reactivity and performance in concrete, and absence of relevant specifications, standards, and test methods have prevented a large-scale use of these pozzolanic materials. This research proposes a concerted effort to advance science, technology, and practice to increase the use of these valuable and underutilized resources to produce long-lasting concrete pavements and structures.