Rotterdam participates in URBCON as this project focuses on reducing the impact of concrete on the environment. It has become clear that the environmental impact of the concrete used so far can be reduced with other raw materials and cement types. It is also the ambition to lower the environmental cost indicator, known simply as ECI (MKI in Dutch), for concrete.
What is ECI?
The ECI value is expressed in a number, and by setting requirements for this value, the impact on the environment can be regulated. ECI is therefore a parameter for realizing environmental ambitions and will become increasingly prominent and inevitable.
It is important to know how the ECI value can be influenced. This includes the extraction of raw materials, the production of cement (based on very high heating), concrete production, transport, use of the structure, demolition, etc. It is an overall collection of environmental influences, yet not harmonized (established in standards). Compiling the ECI value requires a lot of knowledge.
Consequences for applying Urbcon concrete
Rotterdam's contribution to Urbcon is the construction of a bridge with Urbcon concrete, a material consisting of geopolymer cement and remnants of discarded concrete, such as gravel and sand. Several interesting learning points have emerged from this.
The 'ordinary' concrete that is often used in the Netherlands has largely predictable properties. There is a lot of experience with it and a set of calculation rules (Eurocodes) is available with which design, constructive proof, purchasing, manufacturing, implementation, and maintenance can be carried out very efficiently. This process efficiency is absent for the newly developed concrete types, certainly when it comes to constructive concrete (bridges and buildings) and to a lesser extent for non-structural concrete (road pavement).
It has become clear that the existing chain in construction cannot simply be provided with an ECI requirement without affecting the above-mentioned efficient process. With the use of Urbcon concrete it can be stated that work will be done off the beaten track. There is yet no experience available on how the new materials behave in the long term.
This raises the question of how developments can be followed responsibly with the standing organization (of the construction chain), or in which way this organization adapts. Tightening environmental requirements for concrete means much more than seemingly simply lowering the ECI number.
Text: Kees Blom