Abstract
Corrosion of steel reinforcement is one of the main causes of damage in concrete
structures. Thus, the detection and prevention of corrosion of steel in concrete is
important for the condition assessment and rehabilitation of reinforced concrete
structures. Corrosion is an electrochemical process requiring an anode, a cathode, and
an electrolyte. A moist concrete matrix forms an acceptable electrolyte and the steel
reinforcement provides the anode and cathode. Electrical current flows between the
cathode and anode, and the reaction results in an increase in metal volume as the iron
(Fe) is oxidized into Fe(OH) 2 and Fe(OH)3 and precipitates as FeO.OH (rust color).
Water and oxygen must be present for the reaction to take place. In good quality
concrete the corrosion rate will be very slow. Accelerated corrosion will occur if the
alkalinity (pH) is lowered (carbonation) or if aggressive chemicals or dissimilar
metals or uneven chemical environment are introduced into the concrete.
The structural capacity of a concrete member is affected by bar corrosion and
cracking of surrounding concrete. Researches conducted on flexural beams found that
in steel with more than 1.5 percent corrosion, the ultimate load capacity was reduced
by 12 percent probably as a result of reduced bar diameter.
The present research introduces an evaluation of the harmful effects of steel
reinforcing corrosion on different kinds of structures. It also suggests a Quantitive
Assessment program to estimate the rate of corrosion and the r esidual bearing
capacity of RC elements containing corroded reinforcement based on mathematical
techniques.