Rehabilitation of Structure with Reinforcement Section Loss (ACI 364.10T-14)

Description

Integrity of reinforcement is fundamental to the strength, ductility, and safety of reinforced concrete structures. Determining the necessity of additional or replacement reinforcement is a primary concern in rehabilitation projects containing corrosion of reinforcing steel. After determining the condition of the reinforcement, remove unsound concrete, clean reinforcement, and provide additional reinforcement as needed. The structural consequences of a 10 percent cross-sectional area loss due to corrosion are usually minor for non prestressed concrete components because there are usually redundancies in design.

Begin by identifying the source, extent and level of activity of reinforcement corrosion (ICRI No. 310.1R; ACI 364.6T), and deter-mining the overall condition and cross-sectional area of the affected reinforcing steel. Remove all unsound concrete; undercut the exposed corroded bars to provide clearance for under-bar cleaning and full bar embedment in the repair material; and secure the repair structurally, so as to ensure the required load-carrying capacity is achieved (Fig. 2). The clear space behind the reinforcing steel should be greater than 1/4 in. (6 mm), plus the dimension of the maximum-sized aggregate in the repair material (ACI 364.6T). Generally, a 3/4 to 1 in. (20 to 25 mm) gap is required to inspect and clean the bar. Place the repair material and encapsulate the bar with it.