Mass Concrete Mixtures Optimized For Temperature Control and Workability

Mass concrete elements are usually heavily reinforced and subject to large thermal change as the concrete cures. The definition of mass concrete is generally based on the minimum dimension of the element, but is more complicated because of the many factors involved. High heat retention in mass concrete causes differential and high temperatures that can result in detrimental cracks. In some applications of mass concrete, high strengths or early strengths are needed, requiring increases in cementitious material contents beyond the usual low amount of cementitious materials needed in mass concrete to keep the temperature from rising too high during cement hydration. Typically, concretes with regular consistency measured by slump test are used in mass concrete elements. However, congestion of the reinforcement in the element combined typically with geometric and placement constraints require concretes with high flow rates, as in self-consolidating concrete (SCC). Such concretes generally have high cementitious material contents for flowability and stability. There is a conflict in the amount of cementitious materials between mass concrete which requires low cementitious contents to control temperature rise and the use of high cementitious contents for early or high strengths and high workability. The cementitious material contents include supplementary cementitious materials, fly ash and slag cement, for durability and to reduce portland cement contents for temperature control. The objective of this study is to investigate and optimize mass concrete mixtures with regards to temperature control and high workability. Also, the definition of mass concrete will be refined in ways that are helpful to Virginia Department of Transportation (VDOT) in taking precautions to avoid problems that can arise during placement and curing