Jan 1, 2021 09:28 PM
https://www.bbc.com/future/article/20200...n-concrete
EXCERPTS: . . . Destruction of this kind is often the cost of using concrete – the most widely used manmade material on Earth. [...] The production of concrete is also a huge emitter of CO2. ... The cement industry generates around 2.8 billion tonnes of CO2 per year – more than any country other than China or the US. In the oceans, concrete is the main construction material, accounting for more than 70% of coastal and marine infrastructure such as ports, coastal defence structures and waterfronts. In China, for example, around 60% of its coast is effectively concrete. Similarly, more than 14,000 miles of the US’s coastline is covered in concrete.
“Concrete is damaging in the ocean because, to put it in place, natural ecosystems are destroyed,” says Alex Rogers [...] “Concrete is a conventional material, everyone understands it, and it is low cost. But really, in this day and age, when we’re looking at much more sustainable ways of carrying out development – whether it’s coastal reclamation or other forms of building – we should be looking at alternative materials that have a lower impact on the environment.”
Those alternatives might already be here. Among them is a substance called ECOncrete, developed as an eco-friendly concrete. Co-founded by marine ecologist Shimrit Perkol-Finkel, ECOncrete produces bio-enhancing concrete products intended to protect and rejuvenate coastlines and marine resources. This is achieved by using a mixture made almost entirely of by-products and recycled materials, and is thus nearly carbon neutral. This mixture is combined with up to 70% slag cement (a by-product of the steel industry which has a low carbon footprint) and is beneficial for marine concrete thanks to its high chloride resistance. The overall result is a low-carbon concrete.
But it is the nature of the concrete-water interface that makes the most immediate difference for local wildlife. Typically, the smooth concrete surfaces of artificial seawalls are not inhabitable for marine organisms. However, by retrofitting them with eco-tiles and panels that are designed with greater surface complexity – grooves, ridges and crevices – it gives room for marine life to colonise and hide from predators and harsh conditions, ultimately improving the biodiversity of the seawalls.
An example of where this appears to have worked is Hong Kong, where shortage of space has meant reclaiming land from the sea has been common for many years. In areas of reclaimed land in the city’s New Territories region, work is ongoing to retrofit four existing artificial concrete seawalls with different types of eco-engineered fixtures: seawall eco-tiles, eco-panels and “armour” units designed to protect tidal pools.
A preliminary test of eco-tiles in the western waters of Hong Kong found that the number of marine species had doubled to 12, compared with the number of species found on artificial seawalls without such fixtures. “The results were very positive, showing that the eco-tiles with enhanced complexity could significantly increase marine biodiversity,” says Kenneth Mei-Yee Leung, a professor of aquatic ecology and toxicology at Hong Kong University.
[...] Furthermore, unlike traditional concrete, which is highly alkaline, the specially designed concrete that is used for fabricating bio-blocks has a pH value (a measure of the acidity of substances) near to that of sea water, which helps to promote the growth of intertidal marine species such as crabs, molluscs, clams, mussels and oysters. The relatively neutral pH value of the bio-blocks is attained by replacing some of the ordinary Portland cement used in conventional concrete with alternative cementitious materials, such as slag cement, which has a secondary benefit of producing lower CO2 emissions.
[...] ECOncrete’s products are already in use across eight countries and six different seas, from seawalls in Hong Kong to the Port of Rotterdam. “Our vision is that in the future, all man-made structures in coastal and marine environments will be designed and built with environmentally sensitive technologies,” says Perkol-Finkel... (MORE - details)
EXCERPTS: . . . Destruction of this kind is often the cost of using concrete – the most widely used manmade material on Earth. [...] The production of concrete is also a huge emitter of CO2. ... The cement industry generates around 2.8 billion tonnes of CO2 per year – more than any country other than China or the US. In the oceans, concrete is the main construction material, accounting for more than 70% of coastal and marine infrastructure such as ports, coastal defence structures and waterfronts. In China, for example, around 60% of its coast is effectively concrete. Similarly, more than 14,000 miles of the US’s coastline is covered in concrete.
“Concrete is damaging in the ocean because, to put it in place, natural ecosystems are destroyed,” says Alex Rogers [...] “Concrete is a conventional material, everyone understands it, and it is low cost. But really, in this day and age, when we’re looking at much more sustainable ways of carrying out development – whether it’s coastal reclamation or other forms of building – we should be looking at alternative materials that have a lower impact on the environment.”
Those alternatives might already be here. Among them is a substance called ECOncrete, developed as an eco-friendly concrete. Co-founded by marine ecologist Shimrit Perkol-Finkel, ECOncrete produces bio-enhancing concrete products intended to protect and rejuvenate coastlines and marine resources. This is achieved by using a mixture made almost entirely of by-products and recycled materials, and is thus nearly carbon neutral. This mixture is combined with up to 70% slag cement (a by-product of the steel industry which has a low carbon footprint) and is beneficial for marine concrete thanks to its high chloride resistance. The overall result is a low-carbon concrete.
But it is the nature of the concrete-water interface that makes the most immediate difference for local wildlife. Typically, the smooth concrete surfaces of artificial seawalls are not inhabitable for marine organisms. However, by retrofitting them with eco-tiles and panels that are designed with greater surface complexity – grooves, ridges and crevices – it gives room for marine life to colonise and hide from predators and harsh conditions, ultimately improving the biodiversity of the seawalls.
An example of where this appears to have worked is Hong Kong, where shortage of space has meant reclaiming land from the sea has been common for many years. In areas of reclaimed land in the city’s New Territories region, work is ongoing to retrofit four existing artificial concrete seawalls with different types of eco-engineered fixtures: seawall eco-tiles, eco-panels and “armour” units designed to protect tidal pools.
A preliminary test of eco-tiles in the western waters of Hong Kong found that the number of marine species had doubled to 12, compared with the number of species found on artificial seawalls without such fixtures. “The results were very positive, showing that the eco-tiles with enhanced complexity could significantly increase marine biodiversity,” says Kenneth Mei-Yee Leung, a professor of aquatic ecology and toxicology at Hong Kong University.
[...] Furthermore, unlike traditional concrete, which is highly alkaline, the specially designed concrete that is used for fabricating bio-blocks has a pH value (a measure of the acidity of substances) near to that of sea water, which helps to promote the growth of intertidal marine species such as crabs, molluscs, clams, mussels and oysters. The relatively neutral pH value of the bio-blocks is attained by replacing some of the ordinary Portland cement used in conventional concrete with alternative cementitious materials, such as slag cement, which has a secondary benefit of producing lower CO2 emissions.
[...] ECOncrete’s products are already in use across eight countries and six different seas, from seawalls in Hong Kong to the Port of Rotterdam. “Our vision is that in the future, all man-made structures in coastal and marine environments will be designed and built with environmentally sensitive technologies,” says Perkol-Finkel... (MORE - details)