Performance of Concrete Patch Repairs: From a Durability Point of View

Abstract

Chloride contamination in reinforced concrete leads to the corrosion of steel bars. Concrete patch repairs are widely practiced as a remedial measure for the mitigation of such corrosion in reinforced concrete structures. The performance of the patch repairs was studied by various researchers in the past. The structural and material aspects of patch repairs have received more attention than the electrochemical consequences of patch repairs in past studies. But electrochemical changes could be the underlying cause for the failure of many patch repairs. This paper reviews the performance of patch repairs from a durability point of view. It covers the formation of incipient anodes, which are the new corrosion sites formed after a patch repair process. The prevailing corrosion mechanism at the incipient anodes is discussed. The performance of patch repairs when modified with corrosion inhibitors and sacrificial anodes is examined. The importance of the selection of repair materials from a durability point is highlighted considering the electrochemical consequences of patch repair.

Characteristics of patch-repaired RC under influenced of chloride ions

“…When some parts of concrete structures reach the end of their design life normally pertains to crack, spall or delamination due to harmful ions such as chloride; patch repair commonly one of the solutions that able to prolong and reestablish their service life [1]. Due to this matter regarding repair and rehabilitate the deteriorated part of the concrete structures, many new introduced and enhanced materials can be used for replacing materials other than conventional Ordinary Portland Cement (OPC) for instance polymer modifier using styrene butadiene, acrylic and some vinyl copolymers [2], [3].…”

“…Although PMM was said able to withstand corrosion attack in repaired concrete structures [5], [6] chloride ions that already existed in substrate concrete especially when it deals with the electrochemical process that consequently contributes to the microstructure changes. A better understanding on this matter is needed since [1], [6] had concerned about the ring-anode effect. The ring-anode effect is said the cause that contributed to macrocell corrosion (macrocell cathode) formed between the steel in repaired concrete and steel in the substrate (macrocell anode).…”