Waste Tire Rubber; A priceless aggregate alternative found in the garbage dump
The world’s population continues to grow, with projections that 70% of the people will be living in cities by 2050; as a result, the necessity of automobiles will increase because transportation more need in cities. According to this consequence, tire demand has surged in recent decades due to the global expansion of the automotive industry and increasing the use of automobiles as major modes of transportation, which has led to an increase in the huge stockpiles of scrap tires.
The Future of Global Tires to 2024 report, published in late 2019, estimates the tire industry will exceed 2.36 billion units in 2019, with total volume growth, predicted to continue to grow at 3.1% per year from 2019 to 2024, and the total industrial tire volume is estimated to reach 2.75 billion units by 2024 (Janine Young, 2020).
According to the US Tire Manufacturers Association (USTMA), the US total tire shipments will reach 336.1 million units in 2021, up from 303.2 million units in 2020 and 332.7 million units in 2019 (Washington, 2021). In 2019, China produced roughly 844.45 million tires, down around 886 million from the previous year, and India had over 192 million tires.
This was an eight percent rise over the previous year (Shangliao Sun, 2021). According to I.Wagner’s statement, Europe manufactured around 5 million tires in 2018 (I. Wagner, 2021). In Bangladesh, it estimates that around 150,000 tons of scrap tires manufacture every year.
As the tire industry produces a huge amount of tires each year, it also produces many waste tires. Samar Raffoul stated that tire waste generation is almost proportional to tire production. In developing countries, waste tire generation expects to be one passenger tire per person, with an estimated 1 billion waste tires produced annually. By 2030, waste tire generation expects to reach 1.2 billion, for roughly 4 billion tires (Thomas et al., 2015).
This massive amount of non-biodegradable waste takes up a lot of space and threatens the environment. In all parts of the world, the disposal of waste tire rubber has become a major environmental problem. Millions of tires are abandoned, thrown away, or buried every year worldwide, and posing a serious environmental issue.
Every year, nearly 1,000 million tires expect to reach the end of their service life, with more than half of these are dumping into landfills or trash without being treated. By 2030, that number would have risen to 1200 million per year. Including the stockpiled tires, there would be 5000 million tires going to landfill regularly.
According to Rubber Manufacturers Association (RMA), over 230 million scrap tires are generated in the United States each year, with approximately 75 million are stockpiling (John Sheerin, 2014). If the Indian scenario considers the total number of discarded tires after retreading twice expected to be 112 million per year.
In Europe 2009, according to the European Association of Tire and Rubber Producers, there dumped 3.2 million tons of old tires. The recovery rate was 96%, of which 18% remanufactured or reused, 38% recycled, and 40% used for energy production (M Bravo, J de Brito, 2012).
Tires dispose of in various ways, including landfilling, incineration, and use as fuel, pyrolysis, and production of carbon black. According to the 1991 edition of ” Markets for Scrap Tires ” published by the United States Environmental Protection Agency (EPA), only 7% of scrap tires are recycled into new products, while 11% convert them into energy. Over 77.6% of tires, or about 218 million per year, are sent to landfills or illegally dumped, with only 5% exported (EPA, 1991).
Landfilling waste tires in open piles produces various issues, including landscape deterioration, mosquito-borne infections, and serious open tire fires that are difficult to put out and take a long time to do so.
The simplest and cheapest disposal method is burning tires, which offers severe fire hazards. It can produce styrene, a hazardous, poisonous gas harmful to humans, and pollutes the natural air. Many used tires burn as fuel in the brickfield, road construction, and other industrial applications in Bangladesh (The Financial Express, 2016).
Tires that have been improperly stored might offer breeding grounds for disease-carrying insects and rodents. Such stockpiles pose serious health hazards, with long-term consequences if not treated correctly.
Furthermore, it has a significant negative influence on human health and the environment due to the dangers of black and carbon smoke emissions and contamination of water and soil due to run-off water and pyrolytic oil released by burning tires.
The random and illegal dumping issue is worrying due to the high expense of disposal and the demand for a vast landfill area for waste rubber.
To properly dispose of a massive amount of discarded tires, innovative techniques to recycle them are important. Therefore, there is an urgent need to find alternative ways to reuse tire rubber for other purposes, and concrete has been identified as a viable option.
Concrete is the most widely used building material on the planet. Current global issues include reducing the cost while increasing the strength and durability of concrete and improving the environmental friendliness of concrete buildings.
This problem necessitates the use of innovative materials that can replace standard concrete components. Tire waste has good strength, ductility, and strain control qualities, and therefore could use as a substitute for concrete components. Rubber can use as a binder or as a substitute for fine and coarse aggregates in concrete and mortar.
Reducing carbon dioxide emissions and improving environmental greenness are two benefits of adding rubber crumbs to any engineered cement composite.
Moreover, natural sand accumulation changes the direction of the river’s flow and causes instability of the riverbed. The use of natural aggregates (river sand, stones, etc.) for concrete production is rapidly increasing in countries worldwide to meet the growing demand for infrastructure development in recent years.
The availability of these natural aggregates has declined due to over-exploitation in several countries. The increasing shortage of natural aggregates has created an opportunity for using by-products as fine aggregates.
The reuse of waste rubber, derived from discarded tires, as a partial or full replacement for natural aggregates in construction, reduces the demand for natural raw materials and reduces the environmental problems associated with tire disposal. These impacts could mitigate by using crumb rubber instead of natural sand in construction to save natural sand.
On the other hand, concrete has limited properties such as low ductility and crack resistance due to the hardening process. The idea of using rubber waste as a sand replacement in concrete has recently gained popularity as a possible solution to the difficulties mentioned above, as it enhances the flexibility and ductility of concrete (Son et al., 2011).
In this regard, several studies were conducted on rubber aggregate obtained from recycled tires as substitutes for natural aggregates in concrete. Rubber aggregates produce from discarded tires by two methods: mechanical grinding at room temperature and cryogenic grinding at temperatures below the glass transition temperature (Siddique & Naik, 2004). Although past research has yielded positive findings, there are still several aspects of substituting volume with rubber aggregate and the effects of rubber particle size and shape on the mechanical properties of concrete that need to investigate further.
Reference:
- M Bravo, J de Brito (2012). Concrete made with used tyre aggregate: durability-related performance. Journal of Cleaner Production, 25, 42–50. https://doi.org/10.1016/J.JCLEPRO.2011.11.066
- EPA. (1991). The United States Environmental Protection Agency Solid Waste and Emergency
Response (OS-301) Policy, Planning and Evaluation (PM-221) EPA/530-SW-90-074A October 1991 Markets for Scrap Tires - . I. Wagner. (2021). • Tire production in Europe | Statista.
https://www.statista.com/statistics/225733/tire-production-in-europe/ - Janine Young. (2020). What the Tire Industry Will Look Like in 2021 and Beyond – Tire Review Magazine. https://www.tirereview.com/tire-industry-2021-beyond/Press Release. (2021). Press Releases | U.S. Tire Manufacturers Association. https://www.ustires.org/newsletter/press-releases.
- Shangliao Sun. (2021). • India – production volume of tires 2019 | Statista.
https://www.statista.com/statistics/736089/india-production-volume-of-tires/ - Sheerin, J. (2014). Scrap Tire Management in the United States
- R Siddique, TR Naik (2004). Properties of concrete containing scrap-tire rubber – An overview. Waste Management, 24(6), 563–569.
https://doi.org/10.1016/J.WASMAN.2004.01.006 - KS Son, I Hajirasouliha, K Pilakoutas (2011). Strength and deformability of waste tyre rubber-filled reinforced concrete columns. Construction and Building Materials, 25(1), 218–226. https://doi.org/10.1016/J.CONBUILDMAT.2010.06.035
- The FinancialExpress. (2016). Turning waste tires into energy.
https://thefinancialexpress.com.bd/views/turning-waste-tires-into-energy - S Kumar, RC Gupta, BS Thomas, P Mehra (2015). Performance of high-strength rubberized concrete in an aggressive environment. Construction and Building Materials, 83, 320–326.
https://doi.org/10.1016/J.CONBUILDMAT.2015.03.012
