Active Protection of Corroded Steel Rebar Embedded in FRP Wrapped Concrete

Abstract

Reinforced concrete is one of the most commonly used construction materials in civil engineering but its durability problems have been obsessing people. The worst of these problems is caused by corrosion of steel in concrete, inducing the early deterioration of concrete infrastructures. Structural deterioration of reinforced concrete structures affected by corrosion is a gradual process consisting of a few different phases during service life, including corrosion initiation, concrete cracking, excessive deflection and final collapse due to loss of structural strength.

An increasing number of concrete structures are being monitored to enhance their durability. In the last few decades, a number of damage detection techniques such as destructive and non destructive techniques have been developed to analyze the changes in a structure due to corrosion.

A new development in the repair and rehabilitation of RC systems is the use of carbon fiber reinforced polymers (CFRP). These materials have received great attention and their applications to structural repair and retrofit have grown significantly in recent years. CFRP fabrics are largely employed because it offers superior performance such as resistance to corrosion, high stiffness-to-weight ratio, high tensile strength, light weight, high durability and easy installation etc.

The CFRP wraps provide a barrier layer that is expected to impede further corrosion of steel. The FRP sheets, when wrapped around RC members, apply confinement pressure that prevents increase in volume due to rusting. Thus it prevents dislodging of concrete cover. Another important advantage CFRP could be active protection of structures using CFRP wraps as anode. The unique proposition of the present thesis is the use of FRP wraps as anode for active protection. However, it is important to maintain high and uniform electric conductivity of the wrap for effective protection. This thesis investigates carbon FRP (CFRP) composites for active protection of RC structures by using non destructive monitoring techniques.