Combined effects of chlorides and sulphates on cracked and self-healing concrete in marine environments

by Mathias Maes

Institution: Ghent University
Year: 2015
Keywords: Technology and Engineering
Record ID: 1074599
Full text PDF: http://hdl.handle.net/1854/LU-5929641


Concrete is a well-known construction material with a lot of positive properties such as high compressive strength, low cost, wide applicability, etc. Therefore, it is commonly used for marine constructions. This type of constructions mostly have an important social function with a high economic impact (e.g. bridges, wharfs, piers, tunnels, etc.), which makes durability a key issue. Nevertheless, a lot of damage is reported for constructions in marine environments. In this aggressive environment, the durability of concrete is strongly influenced by the presence of chlorides and sulphates, the main components of sea water. On the one hand, the sulphate attack degrades the concrete directly by forming expansive reaction products as well as strength decreasing reaction products. On the other hand, chlorides attack the concrete indirectly, by initiating corrosion at the reinforcement steel. In addition, earlyage cracks are a common problem, specifically for the massive structural components. These cracks promote the penetration of the aggressive substances. Thus, fast repair of the cracks is desirable. Without appropriate treatment, the amount and size of the cracks will increase. However, repair costs are large and in some cases repair is impossible due to inaccessibility. So in order to investigate the durability of concrete in marine environments, two main focus points can be defined. Firstly, it is important to understand the attack mechanisms occurring in marine environments in detail in order to understand the cause of the deterioration. Secondly, as a possible solution the material characteristics with regard to crack formation should be improved.