It’s material: constructing sustainably in the 21st century
Using natural materials that have low embodied energy and / or environmental impact has been on the agenda since the late 1960s. Awareness increased after the Oil Crisis of 1973, which, among other things, got people thinking about the fact that resources are finite; in short, energy conservation was a hot topic.
But it was with the United Nations’ 1987 publication of the ‘Report of the World Commission on Environment and Development: Our Common Future’, or the Bruntland Report, as it is more commonly known, that sustainable construction in its contemporary form was born. The report coined the term ‘sustainable development’, which is described in this manner:
“[sustainable development is] the ability to meet the needs of all people in the present without compromising the ability of future generations to meet their own. This report defined a turning point in sustainability discourse since it deviated from the earlier limits-to-growth perspective to focus more on achieving social and economic milestones, and their connection to environmental goals, particularly in developing countries.”
As a facet of that, sustainable construction seeks to replace the traditional concerns in construction (performance, quality, cost) with resource depletion, environmental degradation and healthy environment. These were the principles set by the first sustainable construction conference in 1994:
Minimise resource consumption (Conserve)
Maximise resource reuse (Reuse)
Use renewable or recyclable resources (Renew/Recycle)
Protect the natural environment (Protect Nature)
Create a healthy, non-toxic environment (Non-Toxics)
Pursue quality in creating the built environment (Quality)
As you’d expect, sustainable construction was on the agenda at the recent COP26 in Glasgow. Funding was promised for the new Urban Climate Action Programme (UCAP) to support cities targeting net zero. UH Business and Energy Minister, Lord Callanan said this:
“The world’s urban buildings, including homes, workplaces, schools and hospitals, are responsible for around 40% of global carbon emissions. By 2050, 1.6 billion people living in cities will be regularly exposed to extremely high temperatures and over 800 million people living in cities across the world will be vulnerable to sea level rises and coastal flooding. Accelerating the transition to net-zero emissions for the world’s cities will therefore be vital to achieving the goal of keeping global warming to close to 1.5 degrees.”
Obviously, much of the world’s construction takes place in urban areas; indeed, by 2050, it is estimated that 70% of the world’s population (about 7 billion people) will live in cities. Therefore, it is the building and expanding of cities where sustainable construction is most needed.
Sustainable materials
Following on from that history and context, let’s look at what materials are currently being proposed and used in construction. This 2021 article lists a top 15 of sustainable materials, including bamboo, reclaimed wood or steel, rammed earth, ferrock and timbercrete. The last two are worth commenting upon specifically: ferrock is a relatively new material that uses recycled materials (95%, on average) such as steel dust, or ferrous rock leftover from industrial processes to create a concrete-like material, though stronger. It traps and absorbs carbon dioxide as part of its drying and hardening process and is carbon neutral.
Timbercrete, as the name suggests, is made from a mix of sawdust and concrete. It is lighter than concrete, and consequently produces fewer transportation emissions. The sawdust reuses waste and replaces some of the energy-intensive components of concrete.
But what is wrong with cement? Quite a lot in environmental terms, as this article illustrates:
“It’s been estimated that for every 1000kg of cement we produce, around 900kg of C02 is emitted into the environment and cement alone is responsible for around 5% of the world’s overall C02 emissions.”
This is the reason so much thought is being given to other, more sustainable ways to build.
Two of the more interesting examples are GRP rebar (reinforcement bar) and concretene. The former is a composite made from high strength glass fibre reinforced with vinyl ester resin. The core of the rebar has all the reinforcing fibre (70% by weight) along the length of the bar for maximum strength. It is also 70% lighter than steel. It is claimed that the vinyl ester resin has over 50 years more resistance to corrosive chemicals than polyester resin. Furthermore, the bars are cheaper than steel, plus it is non-conductive so can be used in electrical environments. Rebar stop ends and cable ties are available, too.
The principal reason why it is becoming a popular choice for sustainable construction is that it resists corrosion, as alluded to above. It is a polymer and can withstand extreme weather much more easily than steel. In tests, there has been no loss of strength when subjected to oxidation and chloride ion-based chemical attacks. The lighter weight – about a quarter of the weight of steel – keeps transportation costs down, plus its life expectancy clearly keeps costs down as well, as it will not need to be replaced with the same frequency as other materials. It insulates rather than conducts. Of course, all of these benefits are not just for the construction industry but also for the businesses or people occupying the buildings in which it is used.
Probably the most exciting new material around is Concretene, which is a graphene-enhanced concrete. Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a two-dimensional honeycomb lattice nanostructure. It was discovered at the University of Manchester in 2004. Indeed, it is the Graphene Engineering Innovation Centre (GEIC) at Manchester, in concert with its industry partner, Nationwide Engineering, that has developed Concretene.
Graphene 3-D balls
Just two months ago, Chris Clarkson, MP for Heywood and Middleton, was invited to watch it “being poured into specially designed moulds to help create the world’s first set of benches using the breakthrough concrete mix”. The engineers have demonstrated that it “allows for removal of up to 30% of material from a build project without impacting on its strength or integrity”. That is obviously significant if rolled out at scale across the building supply chain. That would be almost a third less material for every (traditionally concrete-using) building constructed. It is also 30% stronger as a support, due to its improving of bonding at the microscopic level.
It has only taken 18 months to get from laboratory to product, with its first commercial use coming in a slab for the Southern Quarter gym near Stonehenge in May. As it uses tiny amounts of graphene, the existing production system for concrete can be maintained, as outlined by Dr Craig Dawson from GEIC:
“We have produced a graphene-based additive mixture that is non-disruptive at the point of use. That means we can dose our additive directly at the batching plant where the concrete is being produced as part of their existing system, so there’s no change to production or to the construction guys laying the floor."
Concrete production accounts for 8% of the world’s carbon emissions, so a new version of it that is stronger means less is needed to guarantee the structural strength of a building, and consequently less concrete production and fewer emissions. Nationwide Engineering estimated that Concretene could knock 2% off worldwide emissions. That might not sound like much, but that’s a huge amount from just one material. And while it is 5% dearer to produce, the reduced amount required will mean cost savings for the construction sector of between 10 and 20% per customer.
Imagine no more traditional concrete and, instead, the miraculous graphene, which is the world’s strongest artificial material, being used to produce Concretene at speed and scale throughout the whole world?
You can follow the journey of Concretene on Facebook here.