For decades, fly ash, a by-product of coal plants’ power-generating process, has been an important source of SCM for highway infrastructure concrete, enhancing the performance, economic feasibility, durability and sustainability of cement mixtures containing ordinary portland cement. As a result of environmental regulations and a general transition of power utilities’ fuel source from coal to natural gas in recent years, high-quality fly ash has become increasingly scarce. In response, FHWA organized a workshop to illustrate ongoing research related to the pursuit of fly ash alternatives to ensure the sustainability of our Nation’s roadway infrastructure.