Cement production is an inherently carbon-intensive process which represents two thirds of all greenhouse gas (GHG) emissions associated with cement manufacturing. Although humanity has come to depend on cement for construction projects of all kinds, the resulting 1:1 ratio of carbon dioxide (CO2) emissions to cement product is responsible for approximately 5-8% of total anthropogenic emissions. In the face of a worsening climate crisis, the construction industry is searching for effective solutions for reducing the environmental impact of concrete production without sacrificing access to one of the world’s most in-demand materials. Supplementary cementitious materials (SCMs) have been utilized by the concrete industry for decades as a financially advantageous solution for reducing the cement content of concrete mixtures without sacrificing, and in many cases improving, quality. In the appropriate proportions, use of an SCM can also improve the strength and durability of concrete materials. In response to increasing regulation of coal combustion throughout the United States (U.S.) the concrete industry is actively searching for alternative SCMs to replace fly ash, the most popular SCM and a byproduct of coal combustion. This project evaluates a coproduct of phosphoric acid fertilizer production (J-Rox) for use as an SCM in concrete applications and a viable candidate for beneficial reuse. The efficacy of J-Rox as an SCM was determined based on tests of paste, mortar, and concrete samples produced using various types of J-Rox at cement replacement rates of 15%, 20% and 25%. These samples were compared to control samples containing 100% ordinary Portland cement (OPC) and 20% fly ash to evaluate the mechanical performance of the J-Rox SCM. Five (5) different J-Rox materials were tested in paste and mortar applications and the best performing J-Rox were then selected for additional testing in concrete applications. The preliminary testing determined that the gypsum-based J-Rox materials (J-Rox 4 and J-Rox 5) would provide the most comparable performance to fly ash in concrete applications. Results of concrete testing showed that the J-Rox SCM material could be used to create concrete mixtures that performed better than, or comparably to, the control mixtures in tests of strength (compressive strength, modulus of elasticity, Poisson’s ratio) and durability (surface resistivity, unrestrained shrinkage) at cement replacement rates of 15% and 20%. Combining J-Rox in a ternary blend comprised of 15% J-Rox, 35% slag, and 50% OPC was especially successful and could provide a very economical mixture in terms strength, durability, and reduced environmental impact. Environmental impact was evaluated based on the potential of the J-Rox SCM to address all three pillars of sustainability (i.e., the creation of environmental, societal, and economic benefits). These pillars were explored by viewing J-Rox through the lens of industrial ecology (IE) where the circular exchange of resources within the supply chain. The findings of this study suggest that the use of J-Rox as an SCM in concrete could improve the sustainability of the concrete by reducing demand of raw materials and extending the service life of structures through the beneficial reuse of an industrial byproduct.