As durability-based design of reinforced concrete (RC) structures in corrosive environments is highly influenced by chloride-induced corrosion of reinforcing steel bars, this paper first presents brief outline of an experimental investigation recently carried out by the authors on a large number of reinforced concrete test specimens subjected to several scenarios of chloride-driven reinforcement corrosion.
Concrete specimens were prepared with cementitious material content of 350, 375, and 400 kg/m3; water–cementitious ratios of 0.4, 0.45, and 0.5; fine to total aggregate ratios of 0.35, 0.4, and 0.45; and cover thickness of 25, 37.5, and 50 mm. The specimens were then exposed to chloride solution of three different concentrations and were tested for determining corrosion rate using electrochemical and gravimetric-weight loss methods.
Numerical analysis of reinforcement-corrosion rates (determined electrochemically and gravimetrically) was first used to determine statistical correlation between corrosion rates obtained by the two methods. Then, the gravimetric reinforcement-corrosion rate results were utilized for developing regression models for reinforcement corrosion rates in terms of concrete quality parameters, concrete cover-thickness, and chloride concentration.
The regression models obtained for reinforcement-corrosion rates were adapted within an automated analysis-design-methodology using Microsoft Excel solver for durability based optimal design of RC members subjected to specified chloride exposure corrosive environments. Sample results obtained from the design methodology outlined in this paper are summarized for selected case studies of RC beams and columns.
Source: King Fahd University of Petroleum & Minerals
Authors: Saeid A. Alghamdi | Shamsad Ahmad | Adamu Lawan