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A Thematic Network on Performance Based Rehabilitation
of Reinforced Concrete Structures

While today's economic and social development places more and more demands on Europe's infrastructure, resource and budgetary limits restrict how much new construction can take place. As a result more than 50% of Europe's annual construction budget is spent on rehabilitating and refurbishing existing structures including the repair of deteriorated concrete structures. To tackle these issues, CON REP NET has been formed, a European thematic network that aims to develop a performance based approach to the rehabilitation of concrete structures, and promote preventative action for the management of structures.

The problem
Concrete can deteriorate in a number of ways. The corrosion of reinforcing bars is particularly problematic and is a major limitation on the durability of concrete structures; damage from frost and from alkali-silica reactions is less widespread but still significant. And each year a large number of buildings suffer fire damage. All of these forms of damage necessitate repair of the structure.

Unfortunately, building owners face uncertainty over the performance of any repairs on their assets due to a history of poor performance and premature failures of some rehabilitated structures.

On top of all this, the managers of buildings, structures and facilities all over Europe are under pressure to keep their assets operational for minimum cost. For example, in the Czech Republic alone it is estimated that work on dwelling blocks will cost Euro 2.5 billion over the next twenty five years. These buildings need cost-effective and reliable rehabilitation; something that is not easy in the present circumstances.

Tackling issues with CON REP NET
To help address this issue the European Commission, under its Framework Programme 5, has given financial support for a period of 4 years (2002 - 2006) to establish a thematic network on concrete repair, known as CON REP NET. This network of companies and research organisations will investigate the performance of rehabilitated reinforced concrete structures across Europe. This will identify the most effective and reliable repair processes for a range of different applications, allowing the European concrete rehabilitation industry to apply its resources in a more cost-effective manner. Additionally, new repair and rehabilitation strategies will be sought that will achieve better value for money from the applied resources.

The network's goal is to provide building owners and concrete rehabilitation companies with reliable information on the performance of different types of repair. Ultimately, it is hoped that this will allow the performance of the concrete repair technique to be specified to match the durability and strength of the application.

This performance-based approach, whereby the durability and lifetime requirements for the concrete are specified from the outset, is one that is already finding acceptance in the new construction field. It requires a large degree of knowledge of the conditions the concrete will experience and how it will respond during its service.

These are just some of the challenges that CON REP NET will be seeking to tackle over the next four years.

Structure of the network
The network comprises seven principal partners, organising the work load and taking responsibility for its completion. Around 45 organisations have indicated they will contribute their knowledge and experience to the network in four functional groups: owners; consulting engineers; materials suppliers & repair specialists; and research organisations. A further 300 organisations are expected to participate in the network's public activities. These public activities are expected to include workshops, training events, summer schools and symposia.

It is hoped that the network will be able to foster technical co-operation between universities, research centres, knowledge and industrial organisations and property owners. And that it will improve the performance of rehabilitated concrete structures. It will do this by looking to the past, at the present and to future circumstances.

Firstly, a catalogue of past performance will be compiled. This will allow the problems that are encountered in achieving a durable rehabilitated structure to be reviewed; with the goal of identifying the successful factors and the major stumbling blocks.

Secondly, the current industry practices used in the repair of concrete structures will be reviewed and the current state of the art will be researched. Benchmarks for the performance of rehabilitated structures can then be developed.

Thirdly, performance-based concepts will be explored that can aid the industry in making effective and durable repairs in the future. Also, the aspirations of structure owners will be captured. The network can then work with industry to help devise ways to deliver these aspirations and future research, development and technology activities can be planned.

Broadcasting the findings
Throughout the network's lifetime findings and recommendations will be made available. These will include a best practice guidance document; a strategy for developing performance concepts for durable repairs; the future research, development and technology needs; as well as the aspects relating to Construction Products Directive and the European standardisation of performance concepts.

These outputs will be made available through a number of media. Some interactive workshops and training events will be charged for, as will the published technical reports. But press releases, electronic newsletters, public access web site, presentations to organisations and journal papers will be free for any interested parties.