Compressive strength reduction of concretes due to corrosion of reinforcement is one of the main reasons of failure in reinforced concrete structure which has not been taken into account by researchers yet. Therefore, in this article, for the sake of examination of concrete’s compressive strength reduction due to rebar corrosion, reinforced concrete cubic specimens are constructed, and then, accelerated corrosion is applied to them. With fixing all effective parameters in compressive strength except water-to-cement ratio, specimens with different water-to-cement ratios (0.4, 0.45, and 0.5) are constructed with various reinforcements. Finally, compressive strength tests are performed for corroded and non-corroded specimens and reduction in compressive strength is measured under different degrees of corrosions.

The factors associated with concrete carbonation can be classified in three major categories of environmental factors, concrete’s internal-structural factors, and construction-operation conditions. Climate change is expected to cause gradual change in many primary environmental factors, which may accelerate reinforcement corrosion in reinforced concrete (RC) structures. Studies show that CO2 concentration in the atmosphere may rise from 379 ppm in 2005 to 1,000 ppm in 2100. Hence, adoption of suitable measures to protect exposed RC members against carbonation-induced corrosion is essential for countering the future environmental effects which, in turn, requires further investigation on the effect of critical structural factors, such as water-cement ratio and cement content in the concrete mix design, and construction-operation factors, such as concrete cover depth and surface protection, on the durability of RC members. In this study, these factors were investigated through Monte Carlo simulation. The results showed that slight adjustments in some structural and operational factors can significantly reduce the risk of corrosion initiation and ultimately improve the durability of concrete members against corrosion. The effect of each parameter on the probability of corrosion initiation during the design life of a RC structure was analyzed and interpreted using numerical examples.

In this study, meta-heuristic approach of two types of Particle Swarm Optimization (PSO) method is used to calculate corrosion occurrence probability, due to chloride ions penetration and carbonation. The models' eciency is verified by comparing with available examples in technical literature and results of Monte Carlo analysis. According to the analyzes performed, using different probabilistic distributions regardless of probabilistic moments based on real distribution, lead to diverse results. In addition, influence of each eective parameter on corrosion occurrence varies by changing other parameters and by time The eect of concrete cover (d) reduces at corrosion initiation and the corrosion threshold (Cth) slightly increases over time. Almost, the concrete cover is the most important factor, and the corrosion threshold is also the least important factor. The influence of chloride concentration amount at surface (Cs) increases over time, in a way that, it becomes the most important parameter in low-quality concretes after several years. Thus, the precise amount of Cs is of great importance in exact estimation of corrosion and durability design.