The world is going down with global warming. The statistics continue to spike up, telling us different stories about how the earth is getting affected by our recklessness. From the glaciers melting to the Amazon forest on fire, from the emission of gases from industrial zones to the endangerment of marine life, the people keep facing new and tormenting outcomes of their manifestations. The depletion of the ozone layer, the abrupt increase in population, pollution, deforestation, the gradual declination of health and immunity on multiple bio-levels, lead to the need for a sustainable, energy-efficient, cost-efficient, and a durable solution.
According to the estimate, by Euromonitor International, approximately 5.7 trillion cigarettes were produced across the globe in 2013, which is equivalent to about 1.2 million tonnes of cigarette butt waste yearly. The percentage of waste was expected to increase by more than fifty percent by the year 2025 due to an increase in the world population. Cigarette butt (CBs) waste became a threat to the face of the earth based on these statistics. CBs contain more than 4000 chemicals of cigarette smoke, and these filters are made of cellulose acetate, both of the reasons that make it hard for them to decompose naturally, such that it takes them about 18 months to decay.
At this point, we owe great applause to the RMIT(Royal Melbourne Institute of Technology) researchers team led by Dr. Abbas Mohajerani, who looked deeper into the problem of pollution and waste management. They proposed an effective solution for the benefit of all mankind and the development industry, which was to add the filters in the brick mixture. This led to the minimization of global littering of cigarette filters being run off in the waterways and being seeped into the soil in the form of heavy metals such as arsenic, nickel, chromium, etc. By only adding 1% of the filter butt in a brick, one can reduce the energy exhausted in firing bricks by 58%. If 2.5% of the world’s annual brick production incorporated 1% cigarette butts, 48 million tonnes of CBs could be recycled yearly.
So How Does It Work?
Firstly, recycling programs help collect the waste material, i.e. the cigarette butts. CBs are then heated at 105 °C for a day and stored in a plastic bag. They are mixed with a sand-clay mixture and set in a mold to be dried at 105 °C for a day. To test the compressive strength, modulus of rupture, rate of water absorption, total water absorption, and the density of the manufactured bricks, the brick mold is cast out and fired in a furnace at 1050 °C.
As simple as the process may seem, three groups of nine samples in each, were set in varying sizes, densities, and CBs content. Each group was given its own mixing time of 5 min, 10 min, and 15 minutes.
… AND HOW CAN IT SERVE US POSITIVELY?
According to the tests carried out, we come to know the following factors that help determine the pros and cons of bringing CB bricks into industrial use.
Properties of the fired brick
The density of the brick becomes lighter with an increase in the CB content. Lower density bricks are beneficial in construction due to their ability to reduce the dead load in the structure. They are lighter and easier to handle, which reduces transport costs. They have a lower thermal conductivity that determines the heat loss of a building. However, if the CB is increased, more cracks and pores are formed, resulting in the reduction of dry density and strength of the building material, and an increase in the water absorption properties.
Lower thermal conductivity is required to reduce the energy costs for the heating and cooling of a building. If the CB content is increased, the density reduces, and so does the thermal conductivity, which is also advantageous to reduce energy during the process of drying and firing. Mixing time also influences the variability in the thermal conductivity. If increased, the brick becomes denser, thus the thermal conductivity is increased.
Estimated Total Emission (ETE)
The ETE values turned out to be higher than an ordinary clay brick when fired at the same heating rate but dropped significantly at a higher heating rate. The gases emitted were carbon dioxide (CO2), carbon monoxide (CO), chlorine (Cl2), nitrogen oxide (NO), and hydrogen cyanide (HCN). The CB bricks produced higher emissions for HCN, CO2, and Cl2.
The firing energy was saved by 30.8% and 58.4% for bricks with 2.5% and 5% of CB content, respectively. The estimated firing energy saved by integrating 1% CBs into clay bricks is about 9%.
Most of the low-rise residential structures hold a requirement of bricks with a compressive strength greater than 5 MPa. The increase in the percentage of CB content resulted in lower compressive strength ranging from 25.65 MPa to 3.00 MPa (0%-10.0% CB content). The bricks with 7.5-10% of CB content could be used for non-construction purposes, but the CB brick with 5% content or less are acceptable in construction.
Lower density bricks bear advantages in the domain of construction and manufacturing. The total linear shrinkage in CB brick was observed to vary from 6.44-9.01% on increasing the CB content.
Water Absorption Rate
The rate remained within acceptable limits when the CB content in bricks was 2.5-5% but increased when the CB content was increased. This led to the increase in the number of pores and their sizes in the CB brick that made the brick weaker to be used in the construction process.
The success of these detailed experiments helped deduce positive results, which might soon encourage the integration of non-biodegradable or hard-to-decompose wastes in the building material. This is an impressive initiative for building a sustainable environment by changing the approach and perspective. The question remains, why should we choose a CB brick? The reasons are:
- They can reduce cigarette butt litter worldwide.
- They will save the environment by trapping the chemicals and metals released in the decay of CBs.
- They are cost and energy-efficient.
- They can be used prominently in the lightweight construction, but the application may vary according to the quantity of CBs incorporated. Therefore, they can be both load bearing and non-load bearing.
- They have a low thermal conductivity, which is helpful in the reduction of energy required to provide the heating and cooling conditions to a building. Hence, they have good insulation properties.
- Their compressive strength is 85% less than the conventional brick.
- They have low porosity and shrinkage.
- Their water absorption rate can be increased with an increase in the CB content.
REFERENCES 1. Cigarette Butt Bricks - Physical Properties and Advantages. (2019, January 26). The Constructor. https://theconstructor.org/building/cigarette-butt-bricks/29224/ 2. IRJET- Utilisation of Cigarette Butts in Clay Bricks. (n.d.). Issuu. Retrieved May 08, 2020, from https://issuu.com/irjet/docs/irjet-v6i3627 3. Kover, A. (2017, August 20). 5 Coolest Things On Earth This Week. GE Reports. https://www.ge.com/reports/5-coolest-things-earth-week-19/ 4. Kurmus, H., & Mohajerani, A. (2020). Recycling of Cigarette Butts in Fired Clay Bricks: A New Laboratory Investigation. Materials, 13(3), 790. https://doi.org/10.3390/ma13030790 4. Mohajerani, A., Kadir, A. A., & Larobina, L. (2016). A practical proposal for solving the world’s cigarette butt problem: Recycling in fired clay bricks. Waste Management, 52, 228–244. https://doi.org/10.1016/j.wasman.2016.03.012 5. Physico-mechanical properties of asphalt concrete incorporated with encapsulated cigarette butts | Elsevier Enhanced Reader. (n.d.). https://doi.org/10.1016/j.conbuildmat.2017.07.091 6. Wilson, M., & Wilson, M. (2016, May 31). One Plan To Banish Cigarette Butts? Bake Them Into Buildings. Fast Company. https://www.fastcompany.com/3060345/one-plan-to-banish-cigarette-butts-bake-them-into-buildings