Quay walls Greening with Mosses

Abstract

Amsterdam city is currently facing problems of old quay walls and bridges renovation, followed by insufficient greening in the city. This study aims to propose a method to increase Amsterdam's greenery that will add social and environmental value through the renovation work of quay walls. The main objective is investigating how the quay walls can be redesigned to gain improved moss colonization as the primary greening method. The research question is: “How can quay wall elements be designed with improved bio receptivity to stimulate high moss growth coverage that will add social and environmental values to Amsterdam citizens’ wellbeing?”. It is further divided into six sub-questions to gain knowledge of bio receptive definitions and concepts first, followed by the study of bio receptive construction materials properties in the second part. The third part aims to gain fundamental moss knowledge. Afterward, a moss field survey is conducted on construction materials in The Netherlands as the fourth part. The fifth part consists of the moss cultivation technique and experiment to gain more practical knowledge of the construction materials. Finally, with the acquired results, a bio receptive quay wall design with other practical considerations is proposed in the last part. Initiated with fundamental literature research on existing bio colonization works, followed by more specific building materials properties and moss knowledge studies on the first three parts. Afterward, a simple field survey on twelve sites has been conducted to determine moss growth conditions on building materials related to quay walls. Later on, an indoor moss cultivation method through the use of terrarium has been done to gain insights into material properties, ideal growing condition for mosses and moss cultivation technique. Based on the acquired knowledge, a simple quay walls element is redesigned to promote moss growth, keeping the site orientation in mind and moss cultivation practicalities. The first three parts' results will not be described since these are basic definitions and knowledge needed for the following three parts. During the field survey, the importance of moisture for moss growth on building materials is crucial. Therefore, not one specific material property value margin is needed, but a set of material properties and environmental conditions should be satisfied to gain successful moss growth. The duration of direct sunlight exposure will influence the site's moisture condition, which will further affect moss growth. Only twelve moss species were found and identified that are able to grow on construction materials, which is used for the moss cultivation method on the construction materials during the experiments. The use of a terrarium to test moss growth on construction materials followed by a moss cultivation idea gained interesting moss growth results. It turns out that the mosses' growing temperature should be below 25 degrees Celsius at all times, especially during the germination phase, followed by a humidity level above 80 percent. For this reason, significant moss growth results on the terrarium test samples are only gained during the end of the fall season and the winter season when the temperature is below 25 degrees Celsius. Sadly, this method is still uncommon, therefore, not fully understood and controllable; improvement on the temperature and lighting control of the terrarium test method is needed to further develop the terrarium test method into a moss receptivity testing method. Finally, the redesign of the quay wall element focus is to increase moisture gain through capillary action on the masonry finish of the quay walls. This can be achieved by using bricks with an Initial rate of absorption value above 3.0 kg/m2*minute and pointing made of either trass lime or lime 4 | P a g e mortar to promote capillary absorption of the masonry finish. Site consideration regarding quay wall orientation should be taken into account since this will influence the moisture condition and the moss cultivation technique time of application during winter and protection against external factor that prevents moss germination. It is concluded that moss growth on quay walls can be stimulated by particularly improving the moisture condition on the quay walls exterior finish, as moisture was found to be the key parameter that determines the presence or absence of mosses on concrete structures such as quay walls. Resulting in an increase in greenery in Amsterdam city, which can be further translated into social and environmental values such as better air quality by filtering airborne dust, stimulating the ecosystem by producing food for the primary consumer and followed by an increase in the benefits of access to nature to human health. How citizens will perceive the green moss quay walls is unknown, especially since the moss growth comes with other organisms' growth and is not evergreen throughout the whole year and how will the moss growth influence the durability of the material over a long period. Therefore, more studies and experiments regarding moss greening should be conducted to understand this greening method better.