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The new material researchers have dubbed “bio-concrete” is made from American signal crayfish shells, and Japanese knotweed—both of which are problematic invasive species to the British Isles.
Researchers create bio-concrete from knotweed and crayfish shells
Central Saint Martinsgraduates Brigitte Kock and Irene Roca Moraciahave collaborated to create concrete-like tilesthat give new "economic and ecological" value to invasive species. The material for the tiles—which the researchers have dubbed “bio-concrete”—is made from Japanese knotweed and shells from American signal crayfish. These are among the non-native species that are causing the most ecological and economic damage in the UK. By adding value to them, Kock and Moracia hope to incentivise their removal and help restore local biodiversity. —Dezeen
Invasive species removal and control costs the UK around £1.8 billion annually. “The harvested material is incinerated, buried or trashed. We want to stop this waste. We do not want to create a new industry around this product but to relocate the waste the current system is producing.” Moracia told Dezeen. The material can take on a range of different finishes. Source: Dezeen The finished product has a raw, porous texture reminiscent of concrete. The project was commissioned as part of the Maison/0 graduate programme by the LVMH group, which counts Dior and Louis Vuitton among its brands, with the aim of developing a sustainable alternative to current building materials that could be used in luxury store interiors. Kock and Moracia decided to target concrete, a major carbon emissions culprit. Rather than just mitigating its negative environmental impact, they set out to create a substitute that is actively beneficial. Source: Dezeen “We live in a moment when there is no time to question if something should be sustainable; I think our generation understands the need for a sustainable future,” said Moracia. “However we think this is not enough if we really want to make a change. So we wanted to create a positive impact — a regenerative material.” Adding pieces of raw knotweed root creates a marbled texture. Source: Dezeen The researchers looked at finding a new purpose for invasive species, which are among the top five threats to biodiversity worldwide. They chose to use Japanese knotweed and the American signal crayfish. Japanese knotweed was introduced to the UK in the 1800s and has no natural enemies in the country. When left unchecked, it can grow through concrete, compromising the structural integrity of buildings and roads, and overwhelm other plants to damage ecosystems. Similarly, since they started being imported to the UK in the 1970s, American signal crayfish have decimated the native crayfish population. Their tendency to burrow into river and canal banks has changed local water quality, and can lead to floods and infrastructure collapses. Source: Dezeen Kock and Moracia were able to source both species from specialist removal companies, before combining them using a recipe based on the volcanic ash concrete developed by the ancient Romans. “We have followed their principles and created a bio concrete with different recipe variations,” Moracia told Dezeen. The knotweed, which is incinerated after removal, acts as the ash binder, while pulverised crayfish shells are used as the aggregate instead of the traditional rocks or sand, as these can contain fossilised carbon. This dark burgundy colour is created naturally through the curing process. Source: Dezeen Combined with water and gelatine, these ingredients create a strong, homogenous material that cures and hardens without the need for added heat or synthetic colouring. “We have played with the percentages and ratios to obtain really strong results,” Moracia explained. “The final colours and textures depend on the curing time and the aggregate’s chemical reactions with the binder and the water.” The material can emulate the natural texture of stone. Source: Dezeen Through adjusting these variables, the material can take on a range of different finishes to replicate raw concrete or the delicate veining of stone or marble. Its colours vary from a pale, minty green, created by firing the crayfish shell, to a deep burgundy colour that develops in the curing process when pieces of raw knotweed root are included alongside the ash. The tiles are handmade by Kock and Moracia. Source: Dezeen Other versions resemble white marble. At the moment, the project is still in its infancy and Moracia estimates it will take “years of work” to create a standardised product. One crucial hurdle is that building regulations and rules around the disposal of invasive species would need to be changed to allow for commercial use. Currently, invasive species are labelled as hazardous waste once they are removed, making it difficult to repurpose them as raw materials. Source: Dezeen “We want to showcase the absurdity of the classification and disposal rules here in the UK that do not allow anything to be done with those species after they are treated and sealed in bags,” while you can easily order those byproducts online and import them from China for example,” said Moracia. This dark oxblood is the darkest colour in the collection. Source: Dezeen Rather than having them labelled as hazardous waste, Moracia and Koch wanted to integrate them into a production process so that they create economic as well as ecological gain. The tiles were commissioned by LVMH. Source: Dezeen Japanese knotweed (Reynoutria japonica). Reynoutria japonica, synonyms Fallopia japonica and Polygonum cuspidatum, is a species of herbaceous perennial plant of the knotweed and buckwheat family Polygonaceae. It is commonly known as Asian knotweed or Japanese knotweed. It is native to East Asia in Japan, China and Korea. In North America and Europe, the species has successfully established itself in numerous habitats, and is classified as a pest and invasive species in several countries. Source: Wikipedia/W.carter CC0 The signal crayfish (Pacifastacus leniusculus) is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the North European Astacus astacus fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease. The signal crayfish is now considered an invasive species across Europe, Japan, and California ousting native species there. Source: Wikipedia/Astacoides CC BY-SA 3.0
The problem(s) with concrete
Concrete is a major contributor to the climate crisis because its production releases huge quantities of carbon dioxide into the atmosphere. Carbon dioxide and methane are the two greenhouse gas most responsible for global warming.
The carbon dioxide emissions from the production of concrete are so high that if concrete were a country, it would be the third-largest emitter of CO2 behind China and the United States.
Concrete currently accounts forabout 8%of the carbon dioxide being emitted into the atmosphere, dwarfing the aviation industry’s contribution of 2.5%. Concrete’s contribution of CO2 is comparable to the entire agriculture industry, which is responsible for 9% of carbon emissions.
The central ingredient in concrete is cement, which is made by crushing limestone and clay and adding iron ore or ash. The mixture is heated in a kiln to more than 2,600 degrees Fahrenheit, a process that consumes vast quantities of fossil fuel.
When heated, the calcium carbonate in limestone breaks into calcium oxide and carbon dioxide, which is released into the air. The calcium oxide is ground with limestone and gypsum to make cement. Half of the CO2 emissions in the production of concrete come from the reaction that breaks up the calcium carbonate and the other half from the fossil fuels required to heat the kilns and transport the materials.
The climate crisis is a complex problem, requiring simultaneous action in many areas, including concrete production.
The problem with concrete… Concrete is a major contributor to the climate crisis because its production releases huge quantities of carbon dioxide into the atmosphere. Source: Unsplash/Ricardo Gomez Angel
The construction, operation and maintenance of the built environment accounts for 45% of total UK carbon emissions, with 10% down to the build, according to the UK Green Building Council. In addition, 32% of landfill waste comes from the construction and demolition of buildings and 13% of products delivered to construction sites are sent directly to landfill without having even being used. So how can those working in the industry identify construction methods with reduce the environmental impact? Read on to learn how project managers can make their work more sustainable.
