Intelligent Maintenance and Repair of Reinforced Concrete Structures N F O Evbuomwan Research Engineer, Engineering. Design Centre, City University, London, UK. C. J. Anumba Senior Lecturer, Div. of Civil Engineering. & Building, University of Teesside, UK. ABSTRACT This paper reviews the current approaches adopted in the repair and maintenance of reinforced concrete structures in the UK and explores the scope for an intelligent approach based on the use of a knowledge-based system. The concern raised by the increasing and significant amount of capital being spent on the repair and maintenance of reinforced concrete structures makes the consideration of more effective methods of addressing the problems which result from the deterioration of concrete vital. The problems are exacerbated by the myriad of specialist repair products, techniques and practitioners available - these make it difficult for both clients (building owners) and engineers acting on their behalf to adopt the most appropriate combination of repair products and techniques. Knowledge-based system techniques offer considerable potential for improving the diagnosis and subsequent repair of reinforced concrete structures by providing intelligent and objective advice. The benefits of this approach are highlighted in the paper. 1.0 INTRODUCTION Concrete deterioration is one of the main problems currently facing the building and construction industry, and recent records [1] show that an increasing proportion of the capital being spent in the construction industry, is used for the repair of deteriorated concrete structures. In the last few years, the repair of damaged concrete structures has increasingly become a matter of concern for civil engineers and contractors, with a significant number of companies involved in concrete repairs and maintenance, emerging within the construction industry. These companies can be classified into two main groups viz : those involved in material supplies for the repairs and those involved in damage appraisal, product selection and execution of the repair contracts. Concurrently, there has been a proliferation of proprietary repair products and techniques. Most of the companies, tend to advertise themselves as experts in the field of concrete repairs. There are also ample advertisements in product literature, journals and magazines, for one product or the other being the most effective material in remedying any particular concrete problem. It is not uncommon in view of the above, for a client to fall into the hands of an inexperienced or incompetent repair contractor, or be the victim of an inappropriate repair technique. Furthermore, a client may be confused about which repair specialist to approach who would provide a logical, economic and adequate solution to his/her problem. An inexperienced specifier would also not be immune to the confusion that could arise as a result of the multifarious repair products and techniques available. It would also not be impossible for a specialist contractor to be biased against specifying or using the most adequate repair product for a particular repair problem, if his company did not market that product. In a situation where the contractors have to be responsible for selection, application and performance of repair materials and techniques [2], the general tendency in preparing a competitive tender, would be to limit themselves to repair systems with which they have sufficient experience and/or to products marketed by their main, subsidiary or associated companies, even if there are other more efficient and durable products available in the market. The current trend in the UK, where the cost of concrete repairs and maintenance is rising every year, makes it imperative to avoid a situation where an undesired and inconvenient price would be paid for the failure of a repair system, arising from either bad workmanship or inadequate product selection. There is also an urgent need for the optimization of repair and maintenance costs. The consideration of the foregoing points contributed to the basis for the idea of an intelligent maintenance and repair knowledge based advisory system for reinforced concrete structures. This idea represents the focus of this paper. It is envisioned that this system when fully developed, would inter-alia provide a factual, logical, economic and expert recommendation to intending concrete repair clients, while also acting as a useful first hand guide to concrete repair specialist contractors and consultants. The system will include the use of available information and data to arrive at realistic and proper diagnosis of the cause of the concrete problem and then provide a non-biased specialist advice on materials selection and application, and adequate repair techniques required to meet a desired need. Long term quality assured repair procedures would also be considered in the development of the system.