Prediction of properties of concrete based on a new apparent activation energy function

Abstract

In this dissertation, the new prediction model about hydration-related properties was proposed improving the shortcomings of previous models. Concrete is an aging materials, and the properties of concrete change with time. Meanwhile, the heat of hydration in mass concrete structures makes the temperature gradient between inner and outer surface, and the temperature gradient affects the mechanical properties of concrete. The temperature variations by the cold-weather and hot-weather conditions also have the same influence on the concrete. Therefore, it is very important to estimate the properties of concrete according to temperature and aging. Based on the investigation of previous models, the prediction model including modified apparent activation energy function is proposed. The prediction model, in which the equivalent age concept is applied to the apparent activation energy function, can reduce the shortcomings of previous models. Thus it can be suggested that proposed model is more applicable to in-place concrete than previous models. As the apparent activation energy is the characteristic properties of hydration in concrete, various hydration-related properties should be simulated based on the same apparent activation energy function. Proposed prediction model was applied to splitting tensile strength, elastic modulus, and autogenous shrinkage as well as compressive strength. And its possibility of application was identified. Because it is difficult to obtain the generalized formula of the apparent activation energy function for all mixtures of concrete, the method to determine the apparent activation energy function based on the adiabatic temperature rise curve is proposed. According to the analysis of experimental results, the methodology was verified. Therefore, it can be concluded that the proposed model can be applied to predict the properties of concrete exposed to arbitrary temperature condition.