Assessment of historic concrete structures

摘要

Concrete has been used as a construction material for several thousand years. The concrete as known today was only developed around 150 years ago after the technology was all but lost for a millennium after the fall of the Roman Empire. Historic concrete structures therefore generally only date back second half of the 18th century. Structures that date further back are considered to be ancient concrete. The structures that require attention and therefore an assessment generally belong to the more recent period. Concrete can be a very durable construction material and it was initially thought that it could essentially last forever, however, this has subsequently been proven to be wrong. Concrete can deteriorate as a result of structural inadequacies and due to chemical interactions between the concrete constituents, external aggressants and the embedded steel reinforcement. The deterioration patterns vary from purely cosmetic cracking, cracks affecting the structural integrity, ineffective protection against reinforcement corrosion and loss of steel cross sectional area. This paper provides an overview of many of the different types of deterioration that can be encountered in historic concrete structures and how the cause and severity can be assessed using different investigative techniques.