Influence of concrete mix proportions on lifetime flexural load-bearing capacity of RC beams under chloride corrosion of rebars

Abstract

In this research, the effects of mix design parameters on chloride ion diffusion in concrete and corrosion of rebars have been investigated. Effect of parameters such as cement, water to binder ratio, slump, aggregates, and characteristic compressive strength are analyzed using response surface method (RSM). Regression analysis is used to evaluate the electrical resistivity related with each concrete mixture. Subsequently, the corrosion rate is obtained by using the electrical resistivity and chloride migration coefficient. To validate the regression analysis and investigate the effect of rebar corrosion on the flexural behavior of the beam, a finite element software is employed. Corrosion is applied to a selected beam and the load-displacement plots are obtained by analyzing four laboratory samples. The plots show good agreement between numerical and experimental results. Also, the effect of changing only one parameter is observed on the flexural capacity of the selected beam and its life cycle. It is observed that increasing the water to binder ratio, aggregate content, and slump, decrease the flexural capacity of the beam, while increasing the cement content and characteristic compressive strength leads to a positive effect on flexural capacity.