Mass Concrete Mixtures Optimized for Temperature Control and High Workability

Mass concrete is prone to thermal cracking, deleterious chemical reactions, and ultimate strength reduction caused by a high temperature rise. Defining mass concrete has been difficult since many factors affect the thermal behavior and the distress formation. Mass concrete is usually reinforced and may have geometric constraints that require concretes with high workability, as with self-consolidating concrete. For high workability and strength, high amounts of cementitious material are used for stability and low water–cementitious material ratios. Such amounts generally cause high water and paste contents that lead to cracking because of moisture loss and thermal contraction. In this study, a practical and useful definition of mass concrete was explored. Concretes with low cementitious material contents and high workability were investigated. To minimize the total cementitious material and paste contents, optimum aggregate gradations were considered. To achieve and maintain high workability during construction, a combination of admixtures was used that included high-range water reducing, workability-retaining, and viscosity-modifying admixtures. Laboratory testing of concretes with reduced cementitious material contents including high amounts of the supplementary cementitious materials and a combination of admixtures showed that concretes with a decreased temperature rise, high workability, and adequate strength can be obtained.