Influence of corrosion inhibitor and superplasticizer on bond strength development between galvanized rebar and concrete

Abstract

The bond strength between steel rebars and the surrounding concrete is a vital property influencing the structural performance of the reinforced concrete members. The Reinforced Concrete (RC) structures are exposed to varied physical and chemical mechanisms causing corrosion of embedded steel rebars which affects the bond strength between the steel and concrete. The usage of galvanized rebar in RC structures is a promising approach to control corrosion in steel rebars and to enhance the service life of buildings. This experimental investigation analysis the bond performance of galvanized rebar and concrete admixed with Superplasticizer (SP); Sodium Naphthalene Formaldehyde (SNF) based / Polycarboxylic Ether (PCE) based, and Corrosion Inhibitor (CI); Sodium Nitrite based mixed Inhibitor (SNI) / Bipolar Inhibitor (BPI) at an optimum dosage. The compressive strength and FT-IR studies were conducted to validate the experimental test results. The bond strength behaviour was found to be similar for uncoated and galvanized rebar in control concrete. The bond strength parameters, such as usable bond strength and energy involved for 0.025 mm free end slip are similar for chemical admixed concrete, irrespective of the type of SP and CI combination and type of rebar. The FT-IR spectrum analysis of cement mortar samples at galvanized rebar/uncoated rebar-concrete interface showed similar vibrational bands and exhibited completion of the hydration reaction. The addition of SP and CI in tested combinations did not negatively influence the bond strength development between galvanized rebar and concrete.