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Determining the in-place properties of mass concrete placements is elusive, and currently there are minimal to no test methods available that are both predictive and a direct measurement of mechanical properties. This paper presents a three-stage testing framework that uses common laboratory equipment and laboratory-scale specimens to quantify thermal and mechanical properties of mass high-strength concrete placements. To evaluate this framework, four mass placements of varying sizes and insulations were cast, and temperature histories were measured at several locations within each placement, where maximum temperatures of 107 to 119°C (225 to 246°F) were recorded. The laboratory curing protocols were then developed using this mass placement temperature data and the three-stage testing framework to cure laboratory specimens to represent each mass placement. Laboratory curing protocols developed for center and intermediate regions of the mass placements reasonably replicated thermal histories of the mass placements, while the first stage of the three-stage framework reasonably replicated temperatures near the edge of the mass placements. Additionally, there were statistically significant relationships detected between calibration variables used to develop laboratory curing protocols and measured compressive strength. Overall, the proposed three-stage testing framework is a measurable step toward creating a predictive laboratory curing protocol by accounting for the mixture characteristics of thermomechanical properties of high-strength concretes. [ABSTRACT FROM AUTHOR]

This paper evaluated constituent proportions on mechanical and thermal properties of ultra-high-performance concrete. This paper assessed how fine aggregates and fibers at varying proportions enhance cement paste and can improve its mechanical properties to a desired compressive strength, elastic modulus, or tensile strength. Approximately 400 specimens were tested for mechanical properties within four curing regimes and 22 different mixtures. These experiments aimed to add to the body of knowledge found during literature review. Past efforts found in literature have drawn conclusions by varying one ingredient at a time, whereas the current effort systematically varied multiple ingredients. Results showed compressive strength to be due to synergistic relationships between cement paste, fine aggregates, and steel fibers where absence of any ingredient reduced strength. Tensile strength and elastic modulus were dominated by a single ingredient. [ABSTRACT FROM AUTHOR]