If we are seeking sustainability, we must focus on the concrete

Unquestionably, in the coming years, the survival of the human species on earth will be greatly influenced by the rational use of natural resources; which will require a change in mentality and strategies from the construction industry.

Therefore, sustainability is an expression of social responsibility that has to do with saving non-renewable natural resources, with respect for the environment and that is applied over time. Global warming due to the emission of CO2, increasing landfill sizes, and pollutions are the result of these impacts. Rising population density and increasing demand for concrete have exacerbated the situation. Thus, it is required to go for sustainable concrete construction practices.

Concrete is the most widely used synthetic material in the world but also one of the most environmentally unfriendly. Its manufacture alone is responsible for about 5% of global carbon dioxide (CO2) emissions. The effect of concrete is taking place in different stages from the extraction of the raw material until the end of structure life.  In fact, the International Energy Agency (IEA) estimates that for every kilogram of cement produced, around the same amount of CO2 is released into the atmosphere.

Concrete is a construction material that is basically constituted by the mixture of aggregates, cement, and water, and on some occasions, it also includes components such as additives and additions to improve, change or promote new properties. This material has been known since ancient times and is still used successfully today for its many advantages and applications. At present, there are massive, reinforced, precast, prestressed concrete, and many more, but little is known about and uses sustainable concrete.

BIO-CONCRETE – Development of a bacteria-based self-healing concrete

At the Technical University of Delft, in the Netherlands, Henk Jonkers have developed bio-concrete, a material that is literally alive and that can regenerate the wear and tear of buildings.

The extraordinary properties of this material are due to tiny living beings: bacteria. To prepare bio-concrete, traditional concrete is mixed with strains of the Bacillus Pseudofirmus bacteria that in their natural state can even inhabit environments as hostile as active volcano craters. The incredible thing about these bacteria is that they form spores and can survive for more than 200 years in the building.

When cracks form in buildings built with this material, the bacteria that inhabit it are exposed to the elements, mainly water. The moisture that penetrates the fissures “awakens” the microorganisms that begin to feed on calcium lactate and, as a final product of their digestion, they secrete limestone. This material seals the cracks in the bio-concrete in as little as three weeks.

There is no limit to the length of the crack that the material can repair, from centimeters to kilometers. However, the cracks must not have a width greater than 8 millimeters.

Bio-concrete can save billions of dollars in the maintenance of structures as varied as buildings, bridges or dams.

The cost of the new product can be prohibitive for large infrastructure projects. According to the newspaper The Guardian, while a cubic meter of traditional concrete can cost slightly less than US $ 80, the new material exceeds US $ 110. That is the main gap that bio-concrete must close.

Cover image: Getty Images

Image 2: Science photo library

Bio-concrete report: https://bit.ly/3eEKeYZ

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