VK's principal structural engineering, Koen Feyaerts, shares insights on the use of green concrete in the Komet Project in Mechelen"

The green concrete for the Komet project in Mechelen was developed by Jacobs Beton in collaboration with Revive and Democo, developer of the project and main contractor respectively, and thus VK architects+engineers, and makes up about a third of the 15,000 m³ of concrete in the residential project.

What exactly is circular about the green concrete?

In the green concrete, 30% of the natural aggregates have been replaced by recycled aggregates - concrete rubble that has been crushed to the right grain size and then washed. So less de-aging. And less waste.

What was the deciding factor in choosing green concrete?

The sustainable added value that could be obtained without loss of quality and which proved cost-neutral.

How did the contractors and builder feel about choosing green concrete?

Revive was positive, but preferred to see it all cost-neutral. Contractor Democo also had no problems putting it into application. They were therefore closely involved in its development. Everyone saw the positive added value, which was in no way accompanied by negative edge effects.

In retrospect, what are the strengths of the new product?

I am repeating myself, but: the sustainable added value without any loss of quality. Moreover, because a BENOR seal of approval has now been obtained, it is easy to order and widely applicable.

Are there certain elements or details that could be improved?

We still need to obtain additional security for use with critical elements, although no real problems are expected a priori.

Are there certain things an architect should consider when choosing this product?

The polishability is limited. So for polished application, the green concrete is rather unsuitable. Furthermore, the concrete may also not be used for all environmental classes. For applications that require the use of de-icing salts, for instance, green concrete is less suitable.

For which types of projects is this product particularly interesting and for which types less so?

It is very suitable for all buildings. For applications in infrastructure - see also previous answer - more preconditions have to be taken into account and it is therefore less suitable.

Is the price of building with this product higher than that of traditional construction?

Depends on the plant that produces it. In any case, Jacobs offers this circular concrete at the same price as traditional concrete, from the sustainable point of view it wants to take. After all, in principle, production costs are currently still slightly higher, but it is therefore the plant's choice whether or not to pass on that extra price to contractors.

Source interview: https://www.circubuild.be/nl/n...