This dissertation includes both experimental and analytical investigations of concrete mixtures containing supplementary cementitious materials to identify sustainable alternatives to Class F fly ash for use in Georgia’s mass concrete structures. The primary goal of this study is to optimize the long-term performance of massive concrete structures. This goal is achieved by identifying concrete mixtures that reduce the potential for thermal cracking caused by the heat of hydration of cementitious materials and by developing design charts that assist in design calculations of mass concrete structures. Through this study, ternary replacement mixtures are identified as potentially suitable for mass concrete placements. Additionally, temperature prediction models based on a coupled thermal-structural analysis are developed to aid in maximum temperature and temperature differential predictions. Among the 45% cement replacement mixtures considered in this study, the ternary mixture with 30% slag and 15% metakaolin replacements achieves superior performance in terms of mechanical properties, durability, and thermal cracking potential from heat of hydration. The experimental and analysis results show that the maximum temperature differential limit of 35 °F (19.4 °C) specified in the current GDOT’s Special Provision for mass concrete is adequate for limiting the crack width within 0.006 inch (0.1 mm). Placement conditions, including environmental conditions, significantly affect the maximum temperature and temperature differential. The sensitivity analysis of the bridge seal shows the maximum internal temperature limit of 158 °F (70 °C) will only be met in 70% cement replacement mixtures (SL55+MK15 and SL40+FA30). However, the 70% replacement mixtures will not meet the temperature differential requirement unless insulated formwork or cofferdam is used with R-value greater than 3 ft2·°F·h/BTU (0.52 m2·°C/W). For a given volume-to-surface area ratio (V/A) in a mass concrete structure, the charts and tables developed in this study should inform the temperature requirements conforming to a placement condition.