Mechanical and microstructure characteristics of concrete-mixtures designed for durability of rc-structures in corrosive environments

As exposures to chloride-salts are known as prime factors causing initiation and continuity of corrosion-process of steel reinforcement bars in reinforced concrete (RC) structures, it has always been a major concern for designers considering the requirements of structural-durability for targeted-service life of RC-structures in aggressively corrosive environments typically prevalent in coastal regions. Research works previously reported by the researchers have modeled corrosion-process in terms of corrosion-current density, and it was realized that concrete-mixtures design quality and characteristics, degree of exposures to corrosive-agents such as chloride salts, and protective-concrete cover-thickness are now known beyond doubt to be determinant factors as regards RC-structures durability. This research paper is focused on presenting highlights of an extensive experimental investigation carried out on a large number of concrete specimens that were designed, and placed in chloride-salt solution simulating exposure to corrosion-conditions. Results presented in this paper include close-looks at mechanical and micro-structure characteristics with regard to the influence of key design-parameters and exposure-conditions used for test-specimens with various combinations of cementitious materials constituents and proportioning using three replicate-combinations of water-cementitious ratios, fine to total aggregate ratio, and concrete-cover thickness, and with different concentrations of chloride-solution. Statistical analysis of results obtained from a three-year test-program is outlined in terms of one unifying corrosion-process progress indicator, namely, corrosion-current density Icorr, determined by both electrochemicalmethod and gravimetric weight-loss method. The paper presents a general overview of the test program and a summary of sample results on mechanical, strength, and microstructural characteristics obtained from test specimens.