Strength Assessment of RCC Beams Subjected to Corrosion

Abstract

The damage assessment of civil structural members is one of the most important and recently emerging fields in engineering. Deterioration of a structure may occur due to a host of factors such as poor workmanship,improper maintenance, atmospheric effects, accidents, natural calamities. Certain causes like environmental effects, natural calamities cannot be controlled. Therefore, durability of concrete structures especially thoseexposed to aggressive environments is of great concern. Many deterioration causes and factors have been investigated and corrosion of steel reinforcement was found to be one of the major deterioration problems. Thus, an Engineer may need to examine the state of reinforcement in structures for a number of reasons including assessment for change of use or exposure, routine maintenance, or investigating signs of distress. In turn, there is a requirement for a method that can determine simply, accurately and non-destructively not only weather corrosion of reinforcement taking place but also its intensity and the rate of damage. The main aim of this paper is to assess and evaluate the corrosion condition of reinforced concrete beams by using nondestructive test (NDT) methods such as half-cell potential test, rebound hammer test, and ultrasonic pulse velocity test. Also, another thrust of this pilot program is to establish a correlation between the rebound hammer number, and ultrasonic pulse velocity variation versus concrete strength for different degrees of corrosion in turn to interpret the effectiveness of degree of corrosion on NDT values as well as concrete compressive strength. For that, a total of six reinforced concrete beams (150 × 150 × 1000 mm) were considered. An impressed current was applied to beams with different degrees of corrosion (5%, 10%) in order to accelerate steel corrosion. Meanwhile, electrochemical measurements were carried out to obtain open circuit potential. Finally, the results show that the linear regression analysis is the best fit for the compressive strength prediction relationship by using rebound hammer and ultrasonic pulse velocity test at compression as well as tension side of the reinforced concrete beam with different degrees of corrosion (5%, 10%).

Keywords: Corrosion, electrochemical test, ultrasonic pulse velocity test, rebound hammer test, regression analysis