Is Self-healing Concrete the Ultimate Green Material?

05 February 2014


Green building could be on the brink of a revolution in materials following the development of biomass masonry which can be grown using bacterial cultures or repair itself when damaged.

Watch our video about Self-healing concrete with the use of bacteria.

Two award-winning entries in the inaugural Cradle to Cradle Product Innovation Challenge, the results of which were announced in New York City last November, exemplify what could soon emerge as a key, transformative trend in the field of sustainable construction.

Green building start-up bioMason has developed a method for “growing” bricks via the use of bacterial colonies, thus dispensing with the need for energy-intensive manufacturing processes.

The bacteria secrete a natural adhesive which is similar to the material produced by coral formations. This material serves to bind sand particles together in a brick which is sturdy enough for use in the construction of residential housing.

In addition to dispensing with the need for high-intensive kiln firing – a process which accounts for 40 per cent of the cost of masonry, the biomass bricks make use of raw materials as cheap and commonplace as salt and yeast extracts, and are capable of recycling waste products such as urea.

Another winning participant in the Cradle to Cradle challenge, Ecovative, has developed a biomass insulating material consisting of foam-like fungal colonies.

The key ingredient of the material is a rapid growth species of fungus called mycelium, leavened with agricultural waste products such as seed husks and stalks.

The adaptable nature of the fungus means it can be grown inside molds or the cavities of existing wall structures, or sprayed onto the surface of walls as a form of  a foam.

The mycelium provides a sturdy insulating material which possesses the added advantages of being fire resistant, non-toxic and fully biodegradable.

The next major step for biomass green building materials is the development of a concrete which is capable of organic self-healing, thus reducing the need for expensive repairs.

The Delft University of Technology in the Netherlands is working on the incorporation of bacteria into concrete to confer the material with the extraordinary ability to repair itself when it sustains modest damage or wear. The bacteria produce calcium carbonate – akin to mineral limestone, as a waste product, which can fill in the cracks or holes that so readily beset concrete structures.

Not only does this self-healing propensity obviate the need for expensive and time-consuming repair work, it can also significantly reduce the cost of concrete structures by enabling engineers to dispense with steel reinforcement, which is usually required to prevent cracks from becoming too large.

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