CORROSION INFLUENCE ON BOND BETWEEN STEEL AND CONCRETE

Corrosion of metals in concrete is a continually growing, multibillion-dollar problem, affecting construction, transportation, and many other types of infrastructure worldwide. The influence of corrosion on bond between the reinforcing steel and concrete was studied using a preliminary series of tests on 14 tension specimens, each 100 mm in diameter and 1 m long, and reinforced with one No. 20 bar. The specimens were subjected to accelerated corrosion by immersion in a 5% NaCl solution and subjected to a voltage of 5 v. The relative bond effectiveness of the embedded bars at different stages of corrosion was determined based on the details of the transverse and longitudinal splitting cracks. The bond strength was observed to decrease rapidly with an increase in the corrosion level, dropping from a 9% decrease in the average bond stress for a steel weight loss of 4% to a bond stress decrease of 92% for a weight loss of 17.5%. The latter represented a case of severe corrosion, involving deterioration of the bar ribs.