Concrete is one of the most influential building materials of our time. It is durable, versatile and has outstanding structural and physical properties. Nevertheless, this building material has one major disadvantage: it is responsible for eight percent of global CO2 emissions.
Concrete, the most widely used building material in the world, poses two major sustainability challenges: It causes immense CO2 emissions and requires enormous quantities of sand, which is becoming increasingly scarce. These problem areas require future-orientated solutions to provide new impetus and contribute to the sustainable transformation of construction with concrete.
The search for concrete ideas to overcome CO2 emissions is on
Concrete is one of the most influential building materials of our time. It is durable, versatile and has outstanding structural and physical properties. Nevertheless, this building material has one major disadvantage: it is responsible for eight percent of global CO2 emissions. To be more precise, cement is the real misdemeanour here. When combined with water cement acts as a binding agent that binds the grains of rock in the concrete together and gives the building material strength. During the manufacturing process, however, CO2 is produced as a by-product due to a chemical reaction. Added to this are emissions caused by the energy required to grind the raw materials, heat the kilns, and transport the cement. Innovation is very much in demand and people from a wide range of disciplines around the world are working to find a solution as quickly as possible.
Living concrete: How bacteria can replace CO2-intensive cement
Naturally occurring bacteria can offer a solution for emission-free cement. Combined with a special solution, these bacteria can be colonised on small pieces of rock, and within a few days, they produce a cement-like material that can be reproduced at will. According to the researchers, the material is as hard as cement and the bacteria can work at room temperature, saving energy through reduced CO2. What is more, this new cement reaches its optimal strength in just 72 hours, unlike conventional concrete which takes 28 days after hardening to reach this state.
While research into living concrete is ongoing at numerous universities, the US start-up Biomason has already launched biocement on the market in the form of a brick-like building block. Biolith® is already being used in projects in the USA and Europe, such as flooring in H&M Group stores. Biomason is striving to use biocement material to eliminate 25 percent of CO2 emissions from the concrete industry by 2030.
Self-healing concrete: How bacteria is extending the service life of concrete
Bacteria is also being used to extend the service life of concrete structures through autonomous self-healing technology. Bacteria enclosed in clay balls are being added to fresh concrete so that if cracks appear in the solid concrete, the balls burst and the bacteria inside start to continuously build up limestone mass along the cracks sealing them again within a short time. This self-healing concrete is particularly suitable for structures that are difficult to access for maintenance or are very exposed to the weather. The longer service life of self-healing concrete and the savings on reinforcement due to the larger permissible crack widths leads to a reduction in CO2 emissions and saves maintenance costs.
This idea is not only limited to new builds, the bacteria can also be applied to existing structures that are being refurbished. Dutch start-up, Basilisk is leading the charge in implementing a wide variety of these self-healing concrete solutions. The products are used in construction and renovation projects worldwide, such as tunnel renovation in Holland and in sewage treatment plants in Japan.
The global sand paradox: are we running out of sand?
Our lives are literally built on sand because concrete is predominantly made of sand, making this raw material the megastar of our age. According to the UNEP (UN Environment Programme), a wall 27 metres high and 27 metres wide could be built around the equator with the annual consumption of sand in the construction sector alone!
When you think of the vast quantities of sand in the world’s deserts, you might think that the likelihood of the world running out of sand is almost impossible. The problem, however, is that sand from the desert is not suitable for producing concrete. The grains are too smooth, too round, and too small to be able to bond firmly with cement – an important prerequisite when producing building materials. As a result, the global demand for sand suitable for construction already exceeds the amount that is supplied by erosion and natural transport in rivers.
Political tensions, ecological consequences and natural disasters caused by sand extraction
Due to the increasing demand for sand, which has tripled in the last 20 years, sand mafias are flourishing. In addition to political tensions, extraction is having massive consequences for marine ecosystems and their inhabitants. In Indonesia, for example, coral reefs and fish are being lost due to sand mining and many families are losing income and their livelihoods. The Mekong Delta in Vietnam, for example, has already sunk so far that formerly fertile fields have become salinized. The risk of natural disasters is also increasing. Riverbanks are becoming unstable due to sand extraction and consequently offer less protection against flooding.
How the world’s deserts could counteract the shortage of raw materials
Scientists around the world have stepped up their efforts to get a grip on the sand dilemma. The key question is: how can the approximately 95 percent of the world’s sand that appears unsuitable by current standards be developed and utilised for construction purposes? The German start-up MultiCON has the answers: In MultiCON’s process, grains of sand are finely ground into rock flour and then pressed into pellets. By adding cement and water, the pellets can be processed in high-speed mixers to produce concrete that is even stronger than conventional concrete. Contracts have already been signed with Saudi and German companies for an initial pilot plant. The breakthrough of this technology, which enables the use of desert sand to produce building materials, could curb the devastating political and ecological effects of sand mining.
Bioeconomy as a business model
These technologies are just some of the many promising innovations integrating environmental protection and resource management into the construction industry’s business models. The brief insight into the innovations of the three start-ups highlighted in this article illustrates that sustainability, as an essential cornerstone of the corporate strategy or business model, can combine economic opportunities for companies with ecological aspects of climate change.
In order to anticipate the short to medium-term effects on a company-wide risk profile, it is important to consider not only the opportunities (such as positive material properties) but also any risks that new technologies and products may entail for the company’s own assets or potential liability towards third parties. Scenario analyses as part of an agile risk management process offer approaches for qualitative and quantitative consideration. The focus is on knowledge of the risk potential, i.e., risk transparency, regardless of whether this is to be borne by the company itself or passed on to the insurance market via risk transfer.
With the correct risk management in place, innovations such as these offer possible approaches to overcoming the current challenges for the building industry and open up a green path for concrete construction in which sustainability and efficiency go hand-in-hand.
Laura Hochegger
Deputy Head of Sustainability & Innovation
GrECo Group
T +43 664 822 18 66
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