Summary/Reader Response Final Draft: Concrete That Grows (b)

Scientists create living concrete from bacteria and sand       

According to the article written by Corless (2020), "Scientists create living concrete from bacteria and sand", researchers from the University of Colorado Boulder have created living concrete from bacteria and sand. They have introduced a new living material, by combining sand, hydrogel and bacteria.

Corless explains that photosynthetic cyanobacterium was biomineralized with a 3D sand-hydrogel scaffold, which produces new bricks from the original brick. The article also claims that biological viability and mechanical performance cannot coincide. Thus, additives are incorporated to enhance the quality of the material. Hence, it possesses properties that are comparable to cement-based mortar, which carries biological purposes. Corless interviewed the director of Living Materials Laboratory, who claimed that this process would change people's thinking about the manufacturing industry and reusable materials.

Corless further mentions that despite this technology being in its early development phase, it represents a new era in material manufacturing: a new grade of responsive materials “in which structural function is complemented by biological functions.”

Due to technology’s rapid advancement, there are alternatives to cement concrete. They are turning fungi into 'bricks' for construction materials, using ground granulated blast furnace slag (GGBS) as a partial replacement for cement, and utilising 3D printing formwork for construction. These alternatives could perhaps enhance concrete or replace it in the near future.

Firstly, one concrete alternative is using fungi as a construction material to build houses. According to a news article, written by Begum (2021), researchers from the Nanyang Technological University (Singapore) and Swiss University ETH Zurich (Switzerland), have collaborated to create mushroom bricks from mycelium, a component in fungi. Their research purpose is to optimise growth of mycelium, while infusing it with 3D printing to build mycelium-based structures that could be used for construction. As these fungus grow on waste, mycelium secretes proteins which bind loose materials together to form a web. Naturally, the web forms into a mould, shaped as a block like a brick. These bricks are then heated to stop the growing process. The article explains that mycelium is organic and biodegradable, meaning it’s able to return to nature once its purpose has ended. These building blocks not only serve well in the construction industry, they also do not occupy landfills as they can be composted into fertilisers for plants.

Another alternative construction material is using GGBS. Originally, it is a byproduct from blast furnaces used to produce iron, and it comes in the form of slag from remaining materials. As a byproduct, it may appear to be a waste product that should go to the dump. However, it can serve as an eco-friendly construction material after the slag has been through some curing process, and it produces GGBS. Rajaram, Ravichandran and Muthadhi (2017) reported on a study on ground granulated blast furnace slag (GGBS) to incorporate it into concrete, partially replacing cement with it. From their study, the test results concluded that replacement of GGBS in concrete can produce high strength comparable to conventional concrete mixes. The authors stated that “The workability of the concrete increases with the increase in the GGBS content for M25 grade concrete and the workability reaches its maximum at 50% replacement of GGBS.” This demonstrates that GGBS can replace cement without affecting concrete strength.  

Lastly, another viable alternative to concrete is the use of foam as a material in 3D printing to produce construction structures. Foam in general is an object that traps air, liquid and solid. It is known to be a soft material which comprises many disorientated bubbles of different sizes. It does not have a firm and fixed form. However, according to Hahn (2022), researchers at ETH Zurich, have used 3D-printed recyclable formwork elements to create a precast concrete slab called ‘FoamWork’. Their innovation allows reduction of CO2 emissions from material production in concrete and utilising waste products like fly ash from coal-fired power stations. Incorporating 3D printed recyclable formwork elements with fly ash, helps to minimise the carbon footprint of their foam. Furthermore, the author states, “The final FoamWork elements can either be left in place to improve the insulation of the precast concrete slab or recycled and reprinted to create new formwork”. This suggests that not only is FoamWork eco-friendly, it is sustainable and is able to cut down the usage of concrete.

However, these alternatives are still under development while others are newly out in the construction industry. For instance, the use of GGBS to replace fragments of cement. According to Rajaram, Ravichandran, Muthadhi (2017), although GGBS can be comparable to ordinary portland cement or could produce even better results than cement, it poses issues like long production time due to it setting slower than cement and it takes a longer time to gain its desired strength. This may affect construction schedules.

To conclude, given the advancement of technology, these alternatives to cement concrete can create a new age for the construction industry, either by enhancing concrete or replacing it in the near future.

References:

Begum,S. (2021, November 29). Turning fungi into “bricks” for construction. The Straits Times. https://www.straitstimes.com/singapore/environment/turning-fungi-into-bricks-for-construction?close=true

Corless, V. (2020, January 16). Scientists create living concrete from bacteria and sand. Advanced Science News. https://www.advancedsciencenews.com/scientists-create-living-concrete-from-bacteria-and-sand/

Hahn, J. (2022, February 12). How can we cut the emissions from concrete use? World Economic Forum. https://www.weforum.org/agenda/2022/01/eth-zurich-3d-printer-concrete-carbon-emissions/

Rajaram, M., Ravichandran, A., & Muthadhi, A. (2017). Studies on Optimum Usage of GGBS in Concrete. International Journal of Innovative Science and Research Technology, 2(5). https://ijisrt.com/wp-content/uploads/2017/06/STUDIES-ON-OPTIMUM-USAGE-OF-GGBS-IN-CONCRETE-UPDATED-MANUSCRIPT-.pdf