Thermorheological approach to predict long-term creep of cement mortar from short-term tests

Creep is a long-term deformation that can cause redistribution of stresses, large deformations, and prestress or post-tensioning losses in prestressed or post-tensioned structures, respectively. A major challenge in quantifying the effect of creep in such structures is that creep of concrete is known to continue for decades. In this paper, we examine the time-temperature superposition principle as a method to predict long-term basic creep of mature portland cement mortar from short-term creep experiments conducted at multiple elevated temperatures. For this purpose, we design a unique, miniature version of the standardized concrete creep frame to be amenable to placing in climatic chambers. We use Bažant’s B4 model to verify that the drying creep component of the measured creep behavior is negligible in comparison to the basic creep component. We develop a basic creep compliance master curve for nearly 60 years of deformation at 20 °C using experimental creep data obtained at higher temperatures for test durations of 600 days.