Expert article
Edit 03 May 2021
by Birgit Georgi

The brickwork story behind GreenQuays

Plantgrowth in a wall in special mortar.
Plantgrowth in a wall in special mortar. Image: K. Mulder
Nature-Inclusive Quays (NIQ) are the core of innovative solutions of the GreenQuays project in Breda. The vertical quay walls of the reopened river Mark in the dense historical centre will be green and provide space for flora and fauna, a pleasant place for people and protection against heat and other climate impacts. The intention with the development of a nature-inclusive design is to not just to green the walls but enable naturally the growth of native plants, natural succession and offer thus multiple ecological functions. Behind all the green, there is however a grey foundation - the walls as such that need to be stable and, at the same time, can be invaded by plants. That is the domain of Koen Mulder and his colleagues from Delft University, who experiment with different types of masonry.
Share

Example of typical dutch aesthetic pointing mortar
Example of typical Dutch aesthetic pointing mortar. Image: Alex Kuijpers Voegbedrijf & Gevelrenovatie

When talking to Koen recently, I learned that brick facades that are so typical for the Netherlands have lost their original function over the last decades. They are no longer an element of the structural construction of houses or quay walls but have been turned into aesthetic elements only. The structural construction – mostly made of steel and concrete – is behind the nice facade, which has no longer its original stabilising function. Does that mean that brick walls as structural elements are outdated and useless?

Not so for Koen. He actually finds brickwork and in particular the joints between the bricks highly interesting. He has been keen to explore, if the joints can be given a new function, when the chance to test it out came with the Urban Innovative Action initiative (UIA) and its GreenQuays project. Asked if he could join the project and provide his knowledge, he got very excited about the opportunity to bring research results to real life. The question was, if GreenQuays wants to go for green and nature-inclusive quay walls, what kind of construction needs to be underneath – what kind of bricks, mortar, and construction patterns?

Different options have been tried out in a mock-up at the University’s laboratory. The next step has been to build a small-scale test site in the canal with different wall segments to monitor the different designs and materials under real conditions. These results have been used by the designers of the Real-Life pilot area – a stretch of 175 meters in the city centre – on which materials and patterns to use. Construction will start later in 2021. 

The time to decide on the layout of the small-scale test had been short – just a couple of months until the panels (brickwall segments) had to be erected in spring 2020. Hence, Koen and colleagues had to draw together information from their own research so far and brickwork experience in other cities such as Amsterdam and Rotterdam. They also had to stretch themselves and make some guesses on what could work well – not quite a researcher’s typical approach. At the end, the team selected 3 panels using bricks and different structural mortars and 2 panels with bricks, structural mortar plus a pointing mortar in the outer 2 cm of the joints. While the structural mortar would further stabilise the walls, the pointing mortar could be weaker and optimised to enable plant growth.

scheme with pointing mortar (left) and Koen working on the panels (right)
Scheme with pointing mortar (left) and Koen working on the panels (right)

 

Mortar samples
Mortar samples. Image K. Mulder

Finding the right mixing of these mortars has nevertheless been a challenge. It should still stick to the bricks. Inspiration was taken from the past when, e.g., limewater was used. While experimenting with the different materials, new ideas on material that could work well for plant life surfaced and Koen went for a wild card or “fantasy mortar” how he calls it. This mortar is very unusual. With his background knowledge and a portion of intuition, he had chosen clay, straw, and lime as the ingredients. There aren’t many research results to find on the features and long-term behaviour of such mixtures. For sure, the clay will contract under dry conditions and expand in wet weather and the straw is an organic material, which both create porosity that will nurture plant growth. Would the mixture still stick sufficiently? As the lockdown suddenly restricted the access to the University’s laboratory, Koen started experimenting with different mixtures in his garden to find the right combination that would work.

Mortar and plant growth samples in the garden
Mortar and plant growth samples in the garden. Image K. Mulder

 

When I visited the small-scale pilot in September 2020, I could observe plant growth on the different wall segments. It seemed to work – on some panels better than on others. I even had the impression that on one panel, the plants have been thriving particularly well. And indeed, Koen confirmed to me that this was the panel with the phantasy mortar that only had come up while working with the layout of the small-scale test site and by the exchange with colleagues. It has been a “lucky guess”. 

plant growth on the small scale test panel with "fantasy mortar"
Plant growth on the small scale test panel with "phantasy mortar". Image K. Mulder

Despite excitement about the plant growth in this particular pointing mortar, it has not made it yet into the design of the Real-Life pilot. The mortar has been too new, too little tested yet and the risk was perceived too big for Breda municipality that wants to build something lasting. In addition, the small-scale test site shows that the mortar pollutes the wall over time, which is in conflict with the aesthetic appearance aimed for. However, panel 4 with the alternative, more conventional pointing mortar was the compromise to be applied.

Anyway, even if it has been too early for using the most innovative mortar for the constructions in GreenQuays, at the small-scale test site, it will further deliver data on the longer-term qualities. There are other sections of the river that will be reopened in the years to come and other projects concerning walls; and maybe, the material is sufficiently tested and improved until then? Koen is on the go and is already experimenting with further innovative wall constructions like dry-stack techniques. It is exciting to see that the UIA enables such experiments which otherwise would run behind laboratories’ doors instead of coming to life. 

With the next article, I will take a closer look on how the expectations of plant life have been met on the small scale test site. 

Find more information on: https://www.greenquays.nl

Other news from this project

people watching the opening ceremony

Green Quays from a citizen perspective

Green Quays offers valuable lessons for harmonising urban developments with the desires and needs of their citizens. It has been a radically innovativ...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Image of the built GreenQuays from above

"You have to take risks to advance - also as a politician."

It is done! September 2023 – the GreenQuays have been built. In the middle of Breda, a new stretch of the river Mark has been uncovered and a new type...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
construction of the GreenQuays

The GreenQuays project on its last mile - Journal 3

The third Journal of GreenQuays explores how the project continues to deal with seven general implementation challenges of innovative project as well ...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Nature based solutions
Monitoring a quay wall by volunteers

Volunteers play an important role in GreenQuays’ biodiversity monitoring

The main innovative feature of the GreenQuays in Breda is to build them nature-inclusive. For achieving this, the construction will lay the foundation...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Nature based solutions
Left: construction work on the quays. right: visualisation of greened quays

Bringing to life Breda’s nature-inclusive quays

This Zoom in 2 looks into the experience, challenges and lessons learned with developing the multifunctional design and the implementation. Can it be ...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Nature based solutions
Plant grow on the drystackwall

Ideas from the GreenQuays project start stretching beyond the initial plans

While most of the innovative tasks of planning the quays and testing different technical solutions have finished, GreenQuays is still running with the...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
construction work

Finally digging of the GreenQuays starts

After 2,5 years of preparation the construction of the GreenQuays has started end of June 2022. A first stretch of the covered river Mark in Breda‘s c...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Creating a Map of opportunities

City safari and Map of opportunities – testing new co-creation forms in Breda

Breda is on the way to re-open its first pilot section of the broader river Mark projects, in which the city will bring back the old river Mark in the...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Nature based solutions
Visualisation of an implemented part of the green ways

Making Breda’s nature-inclusive quays also climate-responsive

GreenQuays will be a first stretch of the reopened River Mark project in the city centre. The project will enable nature to take the space despite t...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
plants growing in wall

GreenQuays Journal 2: Progress on tackling the major implementation challenges

The second Journal of GreenQuays explores how the project continues to deal with the seven major implementation challenges of innovative projects....

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Interview participants

GreenQuays Zoom-in 1: Making Breda’s nature-inclusive quays health-inclusive

The GreenQuays project in Breda aims to develop and establish nature-inclusive quays. Although it was not in focus when developing the project, this Z...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Ivy-leaved Toadflax growing in joints between bricks

Making trees and wall plants thrive at steep quay walls

Building nature-inclusive quays is the task of the GreenQuays project and, at the same time, its challenge. How can nature be offered space in a dense...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Showing a map of the GreenQuays design

Finding the right design for nature-inclusive quays

The mindset on designing and using public urban space has changed in Breda in the 1990’s. Earlier, the city had decided to cover completely the origin...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Sustainable use of land and nature based solutions
Checking vegetation grow on the walls of the small-scale pilot

GreenQuays Journal 1: the seven major implementation challenges

The first Journal of GreenQuays explores how the project deals with seven major implementation challenges of innovative projects....

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Nature based solutions
An innovative partnership for innovative GreenQuays in Breda

An innovative partnership for innovative GreenQuays in Breda

Coming to the GreenQuays project team in Breda for the first time in June 2020, I have been hooked by the creative design of the planned nature-inclus...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands

Future green quays in Breda

Enabling nature to take over – green quay walls in Breda

Breda is a lovely city. The dense middle-age centre has many small streets and places to stroll around. This density does, however, leave only little ...

GreenQuays - Urban River Regeneration through Nature Inclusive Quays

Sustainable use of land and nature based solutions

Breda - The Netherlands