CORROSION OF COATED AND UNCOATED STEEL REINFORCEMENT IN CONCRETE

Abstract

Corrosion of reinforcing steel is the one of the main causes of deterioration in reinforced concrete structure. During the initial stage of corrosion, the steel volume increases. This creates tensile stresses in the concrete, which can eventually lead to cracking, delamination, and spalling. This potential risk of corrosion in a structure is quite unpredictable. Therefore, this paper examines the influence of accelerated corrosion on the bond between concrete and the coated and uncoated steel bars. The bar coating consisted of epoxy rich in zinc. Six concrete mixes were prepared. Three mixes had cement contents of 300, 400 and 500 Kg/m3 and a water cement ratio of 0.4. In the rest of the mixes, cement was replaced with 10% silica fume and the water to binder ratio was 0.5. The reinforcing bars were placed inside concrete cylinders. After curing for 3 days, the specimens were immersed in a 5% NaCl solution for 7 days while a DC current of 5V flowed through them using a portable power supply. Different tests were conducted such as the accelerated corrosion test (ACT), the pull-out tests, compressive strength, and weight loss. The results show that coating the steel bars while lowering the water cement ratio with the addition of silica fume, reduces the effects of corrosion in reinforced concrete specimens