Research into bioreceptive materials is gaining increased interest. However, while advances are being made on the material side of bioreceptivity, the underlying ecology of urban mosses is still underexposed. This research aimed to determine how the local environment affects the species composition of urban epilithic moss communities and assess which moss species are most suitable for the colonisation of pristine (bioreceptive) concrete surfaces, leading to recommendations for moss species selection to designers and engineers of bioreceptive structures. We conducted a field survey of 137 moss communities on concrete in the Dutch cities of Amsterdam, Rotterdam and The Hague. A total of 26 different species were found, of which the acrocarp species Tortula muralis, Grimmia pulvinata, Ptychostomum capillare, and Orthotrichum diaphanum and the pleurocarp species Brachythecium rutabulum, Hypnum cupressiforme, and Rhynchostegium confertum acted as most common pioneers and also formed a part of the climax community. We found some positive associations between acrocarp species but negative associations between acrocarp and pleurocarp species. Local environmental factors only played a small role in the community composition at a species level; however, when comparing acrocarp and pleurocarp species, the former preferred more exposed sites, whereas the latter preferred more shaded habitats. As such, we recommend that bioreceptive concrete structures use acrocarp pioneers for exposed locations and pleurocarp pioneers for more shaded locations.

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Implementing nature in cities has great potential to improve urban liveability by providing ecosystem services, which can help mitigate heat stress, improve air quality, attenuate noise, and reduce rainwater run-off. However, widespread adoption of urban nature and green building typologies is still limited due to their costs, environmental impact, and space constraints. Bioreceptive concrete can form the basis of a new green building typology, where the concrete mixture is adjusted to allow for biological growth, specifically mosses, to occur on its surface.

This literature review aims to give an overview of the current state of the art on bioreceptive concrete as a material in general and specifically the (potential) ecosystem services provided by the mosses growing on this bioreceptive concrete.

This review shows that bioreceptivity can be achieved in concrete in several ways, including minor adjustments to standard concrete recipes. While quantitative data on the ecosystem services provided by mosses in an urban context is still limited, potential gains appear significant. The main challenges lie in the durable long-term development of mosses on the bioreceptive concrete and the valuation through quantification of the ecosystem services they provide. However, moss-receptive concrete shows promise as a new green building typology if these challenges are bridged. @en

A bioreceptive material allows for biological content (biofilms) to grow on it, without necessarily affecting the material itself. If a bioreceptive concrete could therefore be integrated into a building façade, it could lead to green façades that do not need additional technical systems. As part of previous research by the authors, a promising bioreceptive concrete mixture was formulated. The aim of this research is to develop this concept by using the previously developed mixture to create a bioreceptive concrete façade panel prototype, made using commonly available materials, that can direct where the biological growth takes place. The latter is done by combining the bioreceptive concrete with a non-bioreceptive (UHPC-based) concrete in the same panel, through a two-stage pouring process. A biofilm was developed on this prototype panel and results show that full coverage of the bioreceptive parts of the panel can be achieved within two weeks under optimal growing conditions and biological growth can be directed. However, exterior survivability is an issue for now. The concept of bioreceptive façades therefore shows promise, yet further investigation into improving exterior survivability is necessary, while further research into the underlying ecology, material, economics, and climate effects is also necessary.@en

Increased urbanisation will put an increasing strain on our green spaces, which is expected to have a significant effect on our physical and mental health, as well as the health of our ecosystems. As such it is important to integrate more green spaces in our urban fabric. One way of doing this is by making use of so-called bioreceptive concrete on our façades and other structures, which allows for biological growth to take place on the concrete substrate itself, without requiring any additional systems or maintenance. However, the challenge is to create an affordable concrete mixture that is sufficiently bioreceptive for biological growth to take place. As such, in our research we test four possible measures to make concrete more bioreceptive: changing the aggregate to CEC (crushed expanded clay), adding bone ash to the mixture, increasing the wcf (water cement factor) and using a surface retarder on the concrete. Of these measures, changing the aggregate to CEC (p = 0.024), the addition of bone ash (p = 0.022) and the use of a surface retarder (p < 0.001) were found to significantly increase bioreceptivity. Increasing the wcf factor, however, was not found to significantly increase bioreceptivity (p = 0.429). It was also found that whereas it was previously though a pH below 10 is necessary for biological growth to take place, this does not appear to be the case. Although further research under natural conditions is necessary, the creation of an inexpensive bioreceptive concrete looks to be feasible.@en