DURABILITY OF CONCRETE: A MAJOR CONCERN TO OWNERS OF REINFORCED CONCRETE STRUCTURES

As long as we used to build concrete structures some of them suffer from durability problems. Think about reinforcement corrosion, alkali aggregate reaction, ettringite formation, frost damage etc. But is it that bad with our structures? As a representative of an owner of a lot of concrete structures I must say no. First of all, let us be happy about that fact! But it cannot be denied that there are some problems, most of the time due to bad workmanship or unknown behaviour of (new) materials. A major concern of an (future) owner of a concrete structure is how to get a robust and reliable structure in term of costs, maintenance and repair. The next question is how to specify requirements for these points in the contract? Can we rely on the existing codes or should we prescribe more details? Specifications concerning durability in existing codes are on an empirical base. The conventional building codes give in principle only construction rules. If these rules are fulfilled, it is assumed that the structure will have an adequate durability. Specifications for durability in terms of service life or years are not given. Therefore, an update of the design method and durability related codes are desired. A performance and reliability based service life (re)design method has been developed for concrete structures in a recent European Brite/Euram project “DuraCrete”. The framework of this method can however be used for other structural and building materials. A further advantage is that it is very similar to the structural design method that is present in most modern structural building codes, like the Eurocode. The method has been put into practice in The Netherlands for the design of several large structures for rail and highway infrastructure. This new approach gives an owner the opportunity the specify his wishes into a contract, while the contractor can ‘play’ with different solutions in order to get to most optimal or cost-effective result. This paper is based on previous publications [1, 2, 3] on the subject of service life design with the DuraCrete method.

• INTRODUCTION

• HISTORICAL OVERVIEW OF SERVICE LIFE DESIGN

• FRAMEWORK FOR PERFORMANCE BASED SERVICE LIFE DESIGN

• SERVICE LIFE DESIGN

• DURABILITY OF CONCRETE SEGMENTS FOR A BORED TUNNEL

• QUALITY CONTROL AND RELIABILITY

• CONCLUDING REMARKS

• REFERENCES