Determination of material properties for structural applications

The safe and accurate prediction of the long-term performance of concrete structures is an important task. As a result, it is fundamental to understand phenomena, which influence the load bearing capacity in course of time. The main source of concrete aging is the ongoing hydration, which is influenced by the concrete mix design as well as the environmental conditions. Current design codes suggest empirical aging functions for some of the material properties, in order to determine strength levels at any given age. However, these equations assume a spatially homogeneous material and express the development of mechanical properties in terms of time, instead of actual hydration degree (curing level), which is a spatially variable temperature dependent quantity. This approach can be problematic for large concrete structures, which exhibit a large gradient of temperature and humidity resulting in a gradient of maturity. Of course, this is an important topic, considering that the assumed material properties, which are tested on small scale specimen, may differ from the real properties in a structural member. Therefore, the real evolution of material properties, depending on the curing conditions is studied based on an example of fastening applications by means of chemomechanical simulations and experiments. The aim of this paper is to compare standard specimens undergoing different curing protocols and anchor tests at 28 days, and in the course of time. As a result, a comparison between the different states of hydration is given for the studied test member and the companion specimen