Sustainable steel solutions for port infrastructure

Durability is an important criterion of sustainability, and one of the major challenges for maritime structures. Steel and reinforced concrete are both affected by this harsh environment. Construction industry is looking for new innovative solutions to increase the service life and reduce maintenance costs during the entire life-cycle. 

The second aspect in sustainability is the environment. Financial considerations will always be a key parameter in the choice of the technical solution, but the world is changing, and in the last years, environmental aspects are gaining more and more importance in the complex decision-making process. 

The inexorable advance in rolling techniques, along with the development of more efficient driving techniques pushed steel sheet manufacturers to improve the effectiveness of their products, the aim being to outperform competitors. For instance, the reduction in weight between different generations of Z-type sheet pile sections with the same section modulus is significant: the new AZ^®-800, launched in 2015, is more than 25% lighter than an equivalent BZ section from the 1950’s. 

Similarly, the high section modulus HZ^®-M steel wall system was launched in 2008 and beats the old HZ system from the 1970’s by at least 10% in weight. Its maximum resistance (maximum section modulus) was more than doubled. 

Additionally, taking into account the increase of up to 30% in yield strength of current steel grades, the mass of steel required to build exactly the same sheet pile structure has decreased in the last decades by more than 50%! 

Corrosion is one the key parameters for the optimization of a steel structure in a marine environment. It is quite difficult to estimate the reduction of thickness of a steel element in seawater, because many parameters influence the corrosion. These parameters can also vary during the service life of the structure. To improve the durability, new steel grades emerged in the last years specifically for marine applications. Based on more than 15 years of exposure of steel samples in seawater in a UK port, measured corrosion rates of steel grade AMLoCor^® in the low water zone and in the permanent immersion zone are up to 5 times smaller than the ones of standard carbon steel.