Structural repair and rehabilitation is a process of reconstruction and renovation of a facility or its structural elements. This involves determining the source of deterioration, eliminating damaged materials and causes of deterioration, and selecting and applying appropriate repair materials that will prolong the service life of a structure. Deterioration of reinforced concrete structures is recognised as a major problem worldwide. Apart from requiring regular maintenance, many structures are in need of extensive repair and rehabilitation.
Over time, as these structures age, we find some degradation or deterioration in these structures with consequent distress manifested in the form of cracking, splitting, delamination, corrosion, etc. Consequently, the need for repair and rehabilitation has grown considerably in recent years. Repair and rehabilitation is the process of upgrading an existing structure to new conditions of use. Its objective is to restore the structure to its original level of service that has now been lost.
In some cases, it is to return the structure to the level of service that was intended but could not be achieved due to deficiencies in the original design and/or construction. Repair methods should be designed with the expected or desired remaining service life of the structure in mind. A distinction should be made between repairs that are intended to stop deterioration completely and those that are only intended to slow down the deterioration processes for a limited period of time. During the course the relevant repair methods for damaged concrete structures are discussed, focusing on design methods, application principles and limitations.
The scope of relevant repair methods includes the application of penetrating corrosion inhibitors and surface coatings, temporary electrochemical techniques, cathodic protection systems, bonded coatings (patch repairs) and crack injection. As an introduction (on the first day), the course also covers deterioration mechanisms, condition assessment principles, non-destructive testing of concrete structures and standards for concrete repair. Repair is the technical aspect of rehabilitation. It refers to the modification of a structure, partially or totally damaged in its appearance or serviceability.
Repair and rehabilitation methods should be designed taking into account the expected or desired remaining service life of the structure. This concerns repairs to the structural elements of the roof, foundations, floors and permanent external walls and supporting columns of the building. It is therefore essential that contractors with the necessary skills and experience are selected for the long-term success of any structural repair programme. Repairs that can be made to improve strength and durability, thereby extending the life of the structure, are not difficult to achieve.
Other methods of structural repair and rehabilitation include pre-packed concrete, epoxy pressure injection bonding, routing and sealing, grouting, etc. There are several types of repair and rehabilitation solutions available, which are discussed below. The success of the repair activity depends on identifying the root cause of the deterioration of concrete structures. These are the most commonly used services for repair and rehabilitation, over time more and more customised services are evolving according to the needs.
In the case of a structure under repair, the steel is usually affected by corrosion; loose rust flakes are removed, preferably around the bar, by abrasive tools or sandblasting, and the rust formed is stabilised with suitable rust converters; a protective coating is then applied on the reinforcing bars, such as an alkaline cement polymeric coating, an epoxy phenolic coating or a zinc-rich paint, etc. If this cause is correctly identified, successful repairs can be made to improve strength and durability, thus extending the life of the structure, which is not difficult to achieve. While the costs associated with repairing deteriorated concrete structures can be considerable, the costs associated with poorly designed or executed repairs can be even greater. Fortunately, while there are many reasons why a building may shift, modern repair technology and advances in application techniques provide effective solutions to address the problem.
A distinction must be made between repairs and rehabilitations that aim to stop deterioration completely and those that only aim to slow down the deterioration processes for a limited period of time. In the case of a patch repair, the concrete cover is usually removed up to about 25 mm beyond the steel bars (which are then cleaned of corrosion products) and a repair material is installed. The technical and economic success of repair projects depends on a number of factors, including proper assessment of the condition of the structure, the design and implementation of repair measures, and the design and implementation of maintenance strategies. In short, structural repair and stabilisation offers a cost-effective, low-impact and environmentally friendly alternative to demolition and reconstruction.