Maintenance and Repair of Concrete Structures of Le Havre, the City Rebuilt by Perret, Inscribed to the World Heritage List

Abstract

The severe damage to the built infrastructure of the Le Havre city and harbor caused by the Second World War made it clear that rapid and economic methods of construction would be required to produce new housing on a massive scale. So post war, various solutions were implemented to increase production of buildings elements, such as open or closed prefabricated precast concrete systems. The sea and industrial surrounding environment of Le Havre and climate conditions (heavy rain, freeze-thaw action) are susceptible to attack the cement, causing surface cracks. Chlorides are particularly common in coastal regions, marine aerosols are transported by the wind. They are very mobile and can penetrate and break up particularly porous concrete. Atmospheric pollution may contain both acids and sulfates. An acidic atmosphere promotes a gradual breakdown and discolouration of the surface cement film. Calcium sulfate and sodium sulfate crystalize as salts inside the pores and disrupt the concrete and the salt action may be a contributor in the decay processes. These environmental conditions are dangerous to concrete structures and can have onset consequences, such as corrosion of reinforcement. As the concrete ages, the alkalinity of the concrete is lost at the exposed surface as it comes into contact with atmospheric carbon dioxide and sulphur that produces acid solutions. With the time, the depth of carbonation and the permeability of the concrete increase. These processes affect the durability of the concrete covering reinforcement. We propose in this article to describe the methodology followed by the city services to manage the maintenance and repair of historic concrete structures, inscribed to the World Heritage list since 2005. Many examples will be presented, such as the St Joseph church, where the last repair are old of 14 years, without actual defaults and on residential buildings, with recent cleaning and concrete patch repairs.