Summary Reader Response Draft 2

According to Corless, the article "Scientists create living concrete from bacteria and sand" (2020) mentions that 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.

The article explains that photosynthetic cyanobacterium was biomineralized with a 3D sand-hydrogel scaffold, which produces new bricks from the original brick. The article states that biological viability and mechanical performance cannot coincide. Thus, additives are incorporated to enhance the quality of the material. The article claims that the new material possesses properties that are comparable to cement-based mortar, which carries biological purposes. Corless interviewed Srubar (2020), the director of Living Materials Laboratory, and he said that this process will change people's thinking about the manufacturing industry and reusable materials. Despite this technology still in its infancy, it represents a new era in material manufacturing: a new grade of responsive materials “in which structural function is complemented by biological functions.”

The prospect of other alternatives to improve concrete or perhaps fully replace it is not impossible as studies and research are being conducted as of today. The environment can also benefit as these alternatives can curb the generous carbon emissions during concrete production. Some of the alternatives are, using microsilica (silica fume) for partial cement replacement, 3D concrete printing, and sugarcane bagasse ash.

Firstly, silica fumes have been used as partial cement replacement. Silica fume is a by-product of high-purity quartz after reduction with coal in an electric furnace. Many researchers have been studying the effect of replacing cement with silica fume on strength and durability aspects of concrete. Scholars from Arni University produced the research article “Study of Partial Replacement of Cement by Silica Fume”, where they replace 0% to 15% of cement with SF, by weight increment. The test results from the study concluded that “The strength of concrete increases rapidly as we increases the silica fume content and the optimum value of compressive strength is obtained at 10% replacement.” Thus, silica fume is suitable to be a substitutional cement material as there is an increase in compressive strength of the concrete.

Another innovative method of producing concrete is 3D concrete printing (3DCP). While 3D printing techniques have been successfully implemented in a multitude of sectors, including aerospace and automotive, concrete construction is still in its infancy. An article from Swinburne University of Technology, Melbourne, “Current Progress of 3D Concrete Printing Technologies” (2017) explains how 3D Concrete printing allows for freeform construction without the necessity of costly formwork, which has numerous advantages over the traditional method of pouring concrete into a formwork. Authors of the article formulated geopolymer-based material for the requirements and demands of commercially available powder-based 3D printers. With abundant carbon emission when producing Ordinary Portland Cement (OPC), geopolymer is a sustainable alternative to OPC. Geopolymer has superior mechanical, chemical and thermal properties and 80% less carbon emissions as compared to OPC. The article concluded that although 3DCP is still an emerging technology, it is rapidly progressing in such a way that 3D printing of large-scale concrete structures may become a reality in near future.

Lastly, the use of waste products’ ashes as cement substitutes. Some waste products that are being utilised in the construction sector are such as sugarcane bagasse, rice husk and seashells. Using sugarcane bagasse ash, a research article by Mehran University of Engineering and Technology, it is used to substitute cement in concrete production. Since SCBE can partially replace the clinker in cement production, it reduces emission of CO2 into the atmosphere. The emissions reduction according to UNFCCC was 519.3 kilo tons of CO2 per year. In addition to this, researchers from Malaysia also reviewed seashells ash as partial cement replacement. By utilizing the waste products to produce the ashes and replacing cement, it partially solves the environmental pollution problems by consuming different wastes will possibly decrease the carbon emissions with reduction of cement production.

Even with the advanced technology today, there are qualities of the traditional concrete that holds supremacy to others. The conventional concrete can source for ingredients easily, possesses high compressive strength and the monolithic character gives much rigidity to a structure.

To summarise, there are innovative researchers attempting to find alternative methods of cement production and these are just a few. The construction industry may have an unprecedented invention such as living concrete. The mixture of sand, hydrogel and cyanobacteria produces a concrete material which is able to reproduce from itself when segregated. This creation pushes beyond the structural boundaries of construction. Nevertheless, it should not stop the never-ending search for new possibilities for alternative concrete production or substitute materials.

References:

Kumar, A. (2016). Study of Partial Replacement of Cement by Silica Fume. Retrieved 9 February 2022, from https://www.journalijar.com/uploads/31_IJAR-11086.pdf

Nematollahi, B., Xia, M., & Sanjayan, J. (2017). Current Progress of 3D Concrete Printing Technologies. Retrieved 8 February 2022, from https://www.researchgate.net/publication/318472250_Current_Progress_of_3D_Concrete_Printing_Technologies

Othman, N. (2017). A review on seashells ash as partial cement replacement. IOP Conference Series: Materials Science And Engineering, 271, 012059. doi: 10.1088/1757-899x/271/1/012059

Supplementary Cementitious Materials in Construction - An Attempt to Reduce CO2 Emmission. (2018). Journal Of Environmental Nanotechnology, 7(2), 31-35. doi: 10.13074/jent.2018.03.182306