The war against plastic has become a crucial part of protecting our planet in the 21st century. With an estimated 150 million metric tons in marine circulation currently, plastic fills our oceans (World Economic Forum, 2016). If it doesn’t end up in the ocean, plastic often fills landfills and takes anywhere from 10 years to 600 to decompose (Wright, 2018). There have been many efforts to reduce plastic in circulation, with the Ocean Cleanup, recycling and preventative actions that promote reusable plastic instead of single use-plastic. However, 8 million metric tons of plastic still enter the ocean every year, and burning plastic releases poisonous substances in the air, including dioxins (WEF, 2018; Saikia, 2012). But, what if there was a way to use the plastic we have already created in a productive way?
Concrete is the world's most popular artificial material as it makes up roads, buildings, dams, and most man made formations-- simply put, it is the crux of most cities in the world (Civil Today). Concrete is created by the combination of cement and an aggregate, such as sand or gravel (Civil Today). Plastic has been shown to act as an effective aggregate that could provide a method to reduce our impact on the environment (CEMBUREAU). Plastic aggregates can be made by grinding plastic waste, such as water bottles or exposing plastic flakes to small doses of gamma radiation and then mixing the powder with cement to create concrete (Saikia, 2012; Chu, 2017). An MIT study found that the concrete created with a plastic aggregate was 15% stronger than traditional concrete. Plastic, when exposed to a harmless dosage of gamma radiation, changes its crystalline structure to become tougher and stiffer. Another study that didn’t use gamma radiation found that concrete with an aggregate plastic would lower the density to create a more lightweight concrete improve it’s toughness, and result in lower thermal conductivity (Saikia, 2012). A concrete with an aggregate plastic is also more ductile than traditional concrete and can thus adjust for injury better than traditional concrete (Saikia, 2012).
Although studies on long term strength and durability of plastic fortified concrete are still underway, the implications for plastic fortified concrete hold especially valuable for countries like India, which face a scarcity in traditional aggregates such as sand and have an overflowing plastic problem. By replacing 10% of the sand in concrete with plastic, they would be able to combat the scarcity of sand as well as reduce the amount of plastic in landfills (Hilten, 2018). The use of plastic as an aggregate would provide an opportunity for those in the concrete industry to reduce their carbon footprint. Currently, concrete production generates approximately 4.5% of human-induced carbon emissions (Chu, 2017), Replacing some of the concrete with irradiated plastic could result in a decrease to the carbon footprint made by the industry (Chu, 2017). Plastic aggregates provide a new opportunity for reducing the plastic bottles and materials in landfills, as well as the plastic waste retrieved from ocean cleanup efforts. Furthermore, plastic’s ability to absorb high energy reactions is a compelling reason for using plastic fortified concrete for building earthquake resistant buildings. The lower thermal conductivity could provide for better insulation that could control heat loss in changing seasons (Saikia, 2012). In many ways, plastic fortified concrete presents a potential remedy to mediate the damages we have done to the environment.
References
25 Different uses of Concrete. (n.d.). Retrieved from https://civiltoday.com/civil-engineering-materials/concrete/215-uses-of-concrete
Cement's solution to plastic waste. (2018, June 26). Retrieved from http://useofcement.cembureau.eu/2018/04/09/cements-solution-to-plastic-waste/fcxz
Chu, J. (2017, October 25). MIT students fortify concrete by adding recycled plastic. Retrieved from http://news.mit.edu/2017/fortify-concrete-adding-recycled-plastic-1025
Hassani, A., Ganjidoust, H., & Maghanaki, A. A. (2007). Use of plastic in concrete mixture as aggregate replacement [Abstract]. Waste Management & Research,28(11), 2041-2047. Retrieved from https://doi.org/10.1016/j.wasman.2007.08.023.
Howard, B. C., Gibbens, S., Zachos, E., & Parker, L. (2019, June 10). A running list of action on plastic pollution. Retrieved from https://www.nationalgeographic.com/environment/2018/07/ocean-plastic-pollution-solutions/
Jacobo, J. (2019, June 08). World Ocean Day 2019: Ocean plastics problem isn't going away, but here's what you can do to help. Retrieved from https://abcnews.go.com/Technology/world-ocean-day-2019-oceans-plastics-problem/story?id=63324490
Saikia, N., & Brito, J. D. (2012). Use of plastic waste as aggregate in cement mortar and concrete preparation: A review. Construction and Building Materials,34, 385-401. doi:10.1016/j.conbuildmat.2012.02.066
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Van Hilten, L. G. (2018, October 15). Could plastic waste be the answer to India's sand shortage. Retrieved from https://www.elsevier.com/connect/atlas/could-waste-plastic-waste-be-the-answer-to-indias-sand-shortage
Wright, M., Kirk, A., Molloy, M., & Mills, E. (2018, January 10). The stark truth about how long your plastic footprint will last on the planet . Retrieved from https://www.telegraph.co.uk/news/2018/01/10/stark-truth-long-plastic-footprint-will-last-planet/