CIGARETTE BUTT BRICKS AS A SUSTAINABLE CONSTRUCTION MATERIAL FOR SRI LANKA

Cigarette butts

Global warming and the environment pollution are critical issues which occur due to the development activities in the world. Cigarettes also contribute to the environmental pollution mainly not in a direct way, but due to the improper disposal of the remaining part of the cigarette after it is used. Since cigarette butts are made of cellulose acetate (a plastic) [5] they have poor biodegradability and it will take many years to breakdown and also heavy metals such as Arsenic (As), Chromium (Cr), Nickel (Ni), and Cadmium (Cd) which are trapped in the cigarette filters leach into the soil and waterways during that process [4].

Figure 01: prepared cigarette butt for brick production [1]

Companies produce about 6 trillion of cigarettes every year and smokers help to make over 1200 million kilograms of cigarette butts waste. In Sri Lanka tobacco use costs LKR 214 billion per year (according to the statistics of 2018) in economic loss with substantial human development losses [6]. Dr.Abbas Mohajerani who led the research project about the cigarette butt bricks at RMIT University said that these numbers can be increased by more than 50% by 2025 mainly due to an increase in world population .Their research results show that if 2.5% of worlds’ brick production with the addition of 1% of cigarette butt amount can be lead to completely offset the annual worldwide cigarette butt production [4].

Figure 02 : Trend of smoking in Sri Lanka in Last 10 years by age groups (2009-2018) [6]

Figure 03 : Dr. Abbas Mohajerani [4]

Advantages of Cigarette butt bricks

Conventional fired clay bricks are one of the most common construction materials since the initial ages of the building construction due to their durability, compressive strength, flexural strength and thermal conductivity than other construction materials. Most of the research activities have proved that incorporation of cigarette butts has significant advantages on behalf of construction industry and also a solution for the environmental pollution. Nowadays, engineers and architects encounter some problems such as the thermal comfort and the noise insulation of dwelling areas of buildings. Since they have invented some solutions such as cooling bricks, ventilation systems and alternative materials for concrete and bricks. Since the cigarette butts have good insulation capability, addition of them into bricks reduce household cooling and heating demands [1]. Cigarette butts cause to improve the noise insulation because they improve the porosity of the bricks than the conventional bricks. In addition to that bricks with CBs (cigarette butts) are lighter and cost effective rather than using other raw materials for manufacturing bricks and cuts the energy needed to fire bricks by up to 58% and that leads to reduce the embodied energy [1]. Since the density of the filters are less than the other materials which are used in the bricks production the overall density was reduced up to 30% [3], depending on the percentage of cigarette butts [4]. Durability of these bricks can be increased with the addition of filters because their biodegradability is less than other raw materials which are used in production.

Physical properties of cigarette butt bricks

Cigarette butts have the physical properties as follows,

• Bulk density – 1.80 𝐠𝐜𝐦−𝟑

• Apparent porosity – 30 %vol.

• Apparent density – 2.42 𝐠𝐜𝐦−𝟑

• Water absorption – 16.65 %wt.

Some of the above mentioned properties of cigarette butt bricks such as density are less than other raw materials while properties like water absorption are higher because most of times the filters consist of tobacco residue, sawdust and grass. Therefore, the water absorption of the bricks increases linearly with the increase of cigarette butt content [1].

Figure 04 : Test cigarette butt bricks with different replacement of Cigarette butts [1]

Physical and mechanical properties of cigarette butt bricks were tested with different percentages of CBs (2.5%, 5%, 7.5%, and 10% by weight) and with the three different mixing times to distinguish the results compared to the conventional clay bricks. In 10% CB bricks the dry density was decreased up to 30% and the compressive strength decreased by 88% and the compressive strength of bricks with 1% CB was determined as 19.53 MPa [2] and this is a suitable value for a one or two storey buildings. Influence of the mixing time was observed by using three different times (5, 10 and 15 minutes) for the bricks with 7.5% CB and 15 minutes brick shows 114% increment of strength and 12% increment for density compared to 5 minutes mixing time [7]. Although the values of water absorption, initial rate of absorption and tensile strength decreased by 22%, 29% and 5% respectively.

As a sustainable solution

Heavy metals and other pollutants which are trapped and immobilized in the solid block when the bricks are fired and they cannot leach and mix with the soil and waterways anymore. In addition to that this is a cost effective product because the cigarette butts are very common in our surrounding and it can be supplied without any cost. Therefore, this can be a turning point of construction industry of Sri Lanka as a developing country.

E.M.K.G.A.D.B.Ekanayake

Department of Civil Engineering

Faculty of Engineering

University of Sri Jayewardenepura.

References

1)    Guide, B. and Masonry, B., 2020. Cigarette Butt Bricks - Physical Properties And    Advantages. [online] The Constructor. Available at: <https://theconstructor.org/building/cigarette-butt-bricks/29224/> [Accessed 19 May 2020].

2)      2020. [online] Available at: <https://www.researchgate.net/publication/297892222_A_practical_proposal_for_solving_the_world's_cigarette_butt_problem_Recycling_in_fired_clay_bricks> [Accessed 19 May 2020].

3)    2020. [online] Available at: <https://www.researchgate.net/publication/279577246_Recycling_cigarette_butts_in_lightweight_fired_clay_bricks> [Accessed 19 May 2020].

4)    Engineersaustralia.org.au. 2020. Double Advantage To Using Cigarette Butts To Make Bricks | Engineers Australia. [online] Available at: <https://www.engineersaustralia.org.au/News/double-advantage-using-cigarette-butts-make-bricks> [Accessed 19 May 2020].

 5)    Longwood.edu. 2020. Cigarette Litter --Filters. [online] Available at: <http://www.longwood.edu/cleanva/cigbuttfilters.htm> [Accessed 19 May 2020].

6)    Tobaccounmasked.lk. 2020. Tobacco Industry Country Profile – Sri Lanka - Tobaccounmasked. [online] Available at: <http://www.tobaccounmasked.lk/index.php/Tobacco_Industry_Country_Profile_%E2%80%93_Sri_Lanka> [Accessed 19 May 2020].

 7)    2020. [online] Available at: <https://www.researchgate.net/publication/272599892_Properties_Improvement_Of_Fired_Clay_Bricks_Incorporating_With_Cigarette_Butts> [Accessed 19 May 2020].