Bio-based construction getting into gear: from a Wageningen lab to practical application in Amsterdam

Working with bio-based materials and reusing construction materials can make a substantial contribution to achieving climate goals. Bio-based materials made from biomass, such as hemp, flax, cattail, or wood, capture CO₂ during growth, and in turn, this CO₂ remains stored when they are used for construction over the long term. Making the production processes in the steel and concrete industry more sustainable can also have a big impact.

Radical changes required

Bio-based and circular materials must be made available on a large scale, so that both residential construction and the infrastructure sector can make the transition towards more sustainable materials. Radical changes are required for this. “We are focusing on the replacement of materials that require a great deal of energy and resources during production, such as cement, asphalt, and premium materials for high-rise construction,” says Arjen van Kampen, business development manager for bio-based construction at WUR. “A variety of projects are being pursued in that area, and AMS Institute is a key link in that chain.” This joint research institute, created by WUR, the Delft University of Technology (TU Delft), and the Massachusetts Institute of Technology (MIT), collaborates closely with the City of Amsterdam and brings partners together.

As the City of Amsterdam is dedicating itself to innovation in construction, it has committed itself to applying innovative approaches and technologies in 10% of its public contracts, together with the scientific and business communities. “We are following the technological developments by WUR, enabling us to suggest materials and methods that may have innovative applications to our partners and the city,” says Joppe van Driel, circularity programme developer for urban regions at AMS Institute. “We conduct testing and monitoring in public space, so that we can determine whether scaling up is possible. In doing so, we create a seamless connection between science and practice.”

That is an important point: there is no time to waste when it comes to achieving climate and emissions goals. Van Driel: “By 2030, the CO₂ emissions in Amsterdam have to be reduced by 55%. The impact of construction on emissions and raw materials is enormous. We need to formulate public contracts properly to even have a chance at attaining this goal. The infrastructure sector is crucial: it can create a tipping point. That is why we are collaborating with major partners, such as the Rijkwaterstaat (editor’s note: the executive agency of the Ministry of Infrastructure and Water Management). This enables certainty regarding the response to market demand, which can be invested in and scaled up. So that we can go beyond that 10%.”

Three different projects

In one of WUR and AMS Institute’s joint projects, they are working on recycling cement with bio-based additives. Used cement must be reactivated to be reused as a binding agent in concrete. That rarely happens at the moment; new cement production is chosen instead. Van Kampen: “On a lab scale, we are currently working on modifying biopolymers in such a way that they bind to the calcium in the cement, but release themselves when the cement is used again. That is done in water at a low temperature. High temperatures up to 1,000 degrees Celsius are required for new cement production, which uses a great deal of energy and leads to a lot of CO₂ production. By reactivating the old cement at a low temperature, it is possible to recycle more cement, while at the same time saving raw materials, emissions of carbon dioxide, and energy by avoiding the production of fresh cement.” The initial results with these biopolymers have been positive. In the next stage of the project, the intention is to produce concrete tiles and test them in the Amsterdam region. The biopolymers can be obtained from industrial residual waste streams. Van Driel sees options for connecting the concrete manufacturers with suppliers of these residual waste streams, ideally at the regional level. “This keeps the production chain short.”

Another WUR-AMS Institute collaborative project is identifying the bio-based materials that are or must become available in order to achieve emission-free high-rise construction in Amsterdam. This involves load-bearing materials, like wood, and fibre crops, like hemp, elephant grass, and flax for sheet and insulation materials. Van Kampen: “How much acreage do we need to cultivate the necessary biomass? Where is this possible in the Netherlands? And how much will we have to import?” There is momentum: the House of Representatives has initiated motions for promoting the cultivation of fibre crops on agricultural land. “Bogs and wetter grasslands are frequently dried out for cows at the moment,” says Van Driel. “CO₂ is released during this process, and cows produce methane. You’d be better off using these wetlands for a crop like cattails. It’s good for the land and for biodiversity. This is nothing new: several centuries ago, a great deal of Dutch wetlands were used to cultivate fibre crops.”

WUR has already been working on making and testing bio-based asphalt for several years and is currently taking that a step further in a third joint project with AMS Institute. Currently, there are roughly 30 test areas in public spaces, like bicycle paths, which are 50% bio-based. “In these test sections, we replaced half of the bitumen, which is petroleum-based, in the asphalt with lignin, the natural biobased binder in wood,” says Van Kampen. “The production of bitumen emits a lot of CO₂, while the lignin from wood actually absorbs CO₂ and stores it for longer in the asphalt. We are striving for 100% bio-based asphalt, and we are trying to develop better monitoring systems in order to collect more data on the quality of the test areas. We have submitted an application to the National Growth Fund for this topic.” “After the testing, other practical issues will come into play,” adds Van Driel. “What machinery is required for this? Can the existing asphalt be reused? Can asphalt also be mixed in at a low temperature? In production terms, focusing on bio-based materials is the best option, but recycling has to be possible too.”

Two-way street

Due to the structural collaboration between AMS Institute, WUR, and the city of Amsterdam, new innovation projects in the area of bio-based construction can be set up quickly, bridging the gap between the lab and practical application. Projects arise from the demand that AMS Institute encounters in its field labs (“market pull”) as well as from the technology-driven opportunities presented by the bio-based technological development at WUR (“technology push”).

That is why these projects function as two-way streets. “AMS Institute is like WUR’s observation deck in the city and vice versa. And they are working on socially relevant construction challenges in Amsterdam,” says Van Kampen. “The short line of communication with AMS Institute is nice, as are our collaborative efforts to bring bio-based construction innovations to the market.”