Delta Concrete Consult has been commissioned by Mobilis-TBI to develop a proprietary DCC recipe for use in a structurally reinforced partition wall of the Vennewatersweg railway underpass in Heiloo. After a successful demo and preliminary laboratory research, all stakeholders in this project were willing to apply this new product for the Netherlands for the first time in a reinforced structural element.

Geopolymer concrete could become a real gamechanger

The geopolymer used for the first time in a railway underpass in the Netherlands in Heiloo coud be regarded as a distant descendant of a 'forgotten' binder concept that was already patented in 1908. It has been adapted by Delta Concrete Consult into contemporary raw materials with the aim of delivering modern performance, with a carbon footprint cut in half compared to traditional blast furnace cement that would otherwise have been used.

In the geopolymer concrete used in Heiloo, the well-known GGBS is used as a raw material because of abundant availability and familiarity within the RMC industry. A strength of the cementless binder system is that there is a much wider range of raw materials available than many perceive. This enables us to consider to use raw materials already close to the jobsite which saves a lot in CO2 emissions from transport. On the basis of preliminary research and ongoing transparent sharing of insights, ProRail, Rijkswaterstaat and main contractor Mobilis gradually gained more confidence in the feasibility of technical equivalent, safe and reliable performance, yet with a significantly lower environmental profile.

It is logical that every stakeholder in the concrete construction process seeks its 'leeway'; everyone wants to control properties during his own production process. For example, the concrete used in Heiloo was given a deliberately extended shuttering time, but despite the cold weather it obtained its design strength levels earlier than ordinary concrete, resulting in the fact that the construction could be put into use earlier. Independent laboratory tests have shown that properties are very similar to traditional concrete and in fact could be regarded as possibly setting a new standard for structural concrete performance aspects such as resistance to chemical attack and thermal stability.

Ministry of Infrastructure and Water Management (Rijkswaterstaat) and national railroad authority (ProRail) show elevated interest

Large public building authorities like e.g. Rijkswaterstaat and ProRail have shown elevated interest in this concept. After undersigning the international Environmental Agreement in Paris by the Netherlands, a national initiative named The National Concrete Agreement, has made larger industrial stakeholders in the construction industry consider looking for sustainable alternatives to common raw materials and products.