1. Introduction
1.1. Background information
This report aims to request for funds to aid on the research on recycling Polyethylene Terephthalate (PET) bottles for construction materials. According to National Environment Agency, it was estimated that 1.76 billion plastic items were used a year in Singapore, and only 6% of the waste plastics were being recycled (NEA, 2017). Out of the 1.76 billion plastic wastes, 467 million are PET bottles. The reason why plastic was used at an abundance is due to its ability to form into different forms and for its durability, but the disadvantage is that plastic items would take centuries to be decomposed naturally and landfills. The plastic that were not recycled would be incinerated and be shipped to Pulau Semakau Landfill (NEA, n.d.). It was originally estimated that Pulau Semakau Landfill would be able to sustain until 2045, but due to the increasing reliance on disposable plastic products, the current estimation is that the landfill would run out of space by 2035 (MEWR, n.d.).
Currently, the two main ways Singapore disposes of waste plastic is by burning it and disposing it to the landfills or sell the waste to other countries that are willing to buy it (Aqil, 2018). The same author also mentioned that the practice of burning waste plastic would cut down the amount of space needed in the landfills, but it is very harmful to our environment.
According to Aqil (2018), It was reported that the fumes produce from burning plastic posed harmful health risk such as, increase the risk of heart disease, aggravate asthma and cause damage to the human nervous system. Aqil (2018) also mentioned that Singapore sold approximately 42,000 tons of waste plastic to China, Malaysia, Vietnam and Indonesia in 2016. With China’s recent announcement of banning imported “foreign garbage”, it would post a major problem as Singapore’s biggest plastic waste buyer is China (Aqil, 2018).
With the plastic waste management challenges Singapore is facing, creative ideas for plastic recycling should be implemented to reduce the harmful impacts. According to BCA, Singapore is expecting to have a higher volume of construction activities per annum, as Singapore is still developing (BCA, n.d.).
The main stakeholders for the application of recycled would be the Building and Construction Authority (BCA), as BCA governing the quality control of all construction materials and methods. Singapore has been using natural resources of fine and coarse aggregates in the mixture of concrete. In a BCA handout, it was stated that ECO-Concrete which are concrete that consisted of 50% or more recycled content (BCA, n.d.).
BCA had set rules and standards for the quality of building materials to be used in Singapore for contractors to strictly adhere to. With the given BCA standards, lab test and research can be done to the recycled polyethylene to be introduced into the concrete as a replacement of natural aggregates (BCA, n.d.).
With the lack of space in Semakau Landfill, the production of air pollution through the incineration of plastics and the significantly low recycling rate, Singapore have to find an alternative solution for disposing of plastic waste. Singapore authorities should start adopting the use of recycling plastics into green aggregates and find alternative ways to incorporate the waste plastic to other forms of construction materials to ultimately reduce the contribution of plastic waste to our landfill.
1.2. Problem Statement
Currently, the percentage of plastic waste not being recycled is at 94%. With the aim of being a “zero waste” nation, the ideal goal is for Singapore to no longer rely on landfill as a means to dispose of our plastic waste, but through alternative methods. One solution is to utilise the waste plastic by converting them into green construction material. With this, not only are we working towards a “zero-waste” nation but also extending the life spend of landfills for other waste disposals.
1.3. Purpose Statement
The purpose of this report is to propose the adoption of green aggregates by recycling waste PET bottles. The aim is to increase the percentage of recycling rate of waste plastic, reducing the usage of space in Pulau Semakau Landfill and lessen the production of air pollution through the burning of plastic waste. Adopting this solution would bring Singapore a step closer to being a “zero waste” nation.
2. Problem Solution
2.1. ECO-Concrete
BCA developed an initiative by encouraging the use of recycled concrete materials by incorporating Recycled Concrete Aggregate (RCA) into the production of concrete. RCA are aggregates that are recovered from the demolition of buildings, where demolition debris are then crushed and sieved into different category of aggregates. (BCA, n.d.)
Sands and granites are deemed as aggregates in the concrete mixture, and the roles of aggregates in a concrete mixture are to give the basic property which determines the concrete behaviour such as durability, strength and workability. The quality of concrete depends heavily on the aggregates properties, which would determine the ultimate property of the concrete produced. As natural resources are of a scar in Singapore, construction companies have to rely on other countries as these natural resources are imported into Singapore. (BCA, n.d.)
According to Thorneycroft et al. (2018), India had been researching on the possible ways to recycle plastic into construction base material in recent years. The research had shown that PET bottles could be ground and blended to achieve sand like textural which allows it to replace natural sand and act as a fine aggregate in the concrete mixture. The same author also mentioned that due to PET having a different chemical property as natural sands, it bonds differently with cement matrix causing the concrete to have a weaker strength and durability. However, by treating PET with chemicals and reducing the size of the PET particles, the reaction bond between the PET and cement matrix is showing improvement (Thorneycroft et al. 2018).
2.2. ECO-Bricks
Brick is a type of building material that used to make walls, pavements and other elements in masonry construction. Bricks are typically made up of shaped clay and are bind together with the usage of cement mortar during construction (Juan, 2018).
Zhuang (2014) stated that during 1990s, houses in Singapore were built out of bricks. The same author mentioned that as technology advanced, Singapore had become “a city of glass and steel skyscrapers” (Zhuang, 2014, para 1). Zhuang (2014) also mentioned that Singapore no longer has any brick factories, hence all brick used in Singapore were imported from overseas. Bricks are no longer visible is because contractors tend to paint over facing bricks or plastering it up so only the plasterwork can be seen and not the bricks (Zhuang, 2014).
According to Fedreico et al. (2017), the properties of an eco-bricks highly depends on the compactions of the filling materials into the bottles, and skilled workers are required to compact the fillers into the bottles to have a desirable brick property. The same author also mentioned that Eco-bricks are required to undergo the flammability test before using the eco-bricks for actual construction works.
Himanshu (2017) mentioned that PET bottles are able to be transformed into construction bricks, by compacting sand into the plastic bottles and giving it the ideal strength which is comparable to original bricks. The same author also stated that by sorting the PET bottles into different size and shape, and a strict selection of suitable PET bottles, the bottles are then compacted and filled with sand, this sand filled bottles are then deemed as ECO-bricks. This ECO-bricks would be stacked and cemented together, creating a partition walls that is made up of plastic bottles and cement mortar (Himanshu, 2017).
3. Benefit
The potential benefits of the proposed solution includes conserving natural resources, relieving stress on landfill and improved properties to concrete.
3.1. Conserving natural resources
According to the Portland Cement Association (n.d.), approximately 60%-75% of the concrete is made up of aggregates, on average 1370 tonnes of aggregates are used a year in Singapore. That contributes to a hefty amount of percentage in the mixture of cement.
In the 4th quarter of 2018, Singapore’s construction industry average usage of cement was estimated to be 377 000 tonnes. Adopting waste plastic aggregates would help conserve natural resources by reducing the need for virgin materials (BCA, 2019).
Figure 1: Forecast and actual construction demand (BCA, 2019)
3.2. Relieving stress on Pulau Semakau landfill
The proposal of the creation and adopting of plastic waste aggregates would redirect substantial amount of plastic waste away from landfills, prolonging the lifespan of Pulau Semakau. It could potentially reduce energy consumption and emissions from burning the waste.
3.3. Improved properties to concrete
Incorporating plastic aggregates improves properties of concrete due to its toughness, low thermal conductivity, high heat capacity and good abrasion behavior. Moreover, the incorporation lowers the densities of the resulting concrete thus developing a ‘lightweight concrete’. This development lowers the earthquake risk of a building and it could be beneficial in the design of an earthquake-resistant building in the future (Semiha, Cengiz, Kubiley, 2010, as cited in Saikia, Brito, 2013)
4. Proposal Evaluation
There are some challenges to overcome in order to achieve our proposed solution. One challenge faced by the team is the cost of sorting plastics. There is no exact cost stated in articles. According to Quah (2018), V1 Recycle’s managing director Richard Lim stated that the sorting process is the costly parts of the process as it requires expensive machines or very skilled workers. On top of that contamination and land constraints affects the cost of sorting plastics. Sorting of the plastics must be done in order to remove contaminated plastics as it cannot be recycled. Skilled workers have to be trained and educated to know and differentiate contaminated and non-contaminated plastics apart.
Mr Dave Wong, a business development manager at A~Star Plastic Recycling, mentioned that the cost of recycling plastics will increase when plastic is contaminated as cleaning and sorting are required (Mahmud, 2018).
In order to raise awareness on the importance of recycling, countries in Latin America such as Argentina, Africa and South Asia have started adopting Eco-Bricks as part of a community project where everyone works towards a common goal.
Ecoinclusion - a non-profit foundation, was created in the hopes of solving environmental and infrastructure problems. With the lack of decent housings, they decided to manufacture Eco-bricks where it has the same properties as common ceramic bricks yet lighter and has a better insulating and soundproofing properties. With this, they have the same objectives as A-Green-Gates. They are reducing plastic pollution, increasing awareness on the importance of recycling and help those sectors in need (Ecoinclusion, 2018).
The team consulted with Dr Fei Jin, a professor in civil engineering materials. He postulated that Singapore’s construction companies have been sticking to traditional methods due to their stubbornness and the cost of the construction. According to Ng (2017), property consultant Nicholas Mak of SLP International mentioned that companies will stick to traditional methods if it is cheaper. The purchase of machinery, computer software and training of staffs will usually result in higher cost. High-cost methods will result in local companies sticking to their traditional method.
5. Research and Methodology
5.1. Primary Research
A survey questionnaire was posted online to a total of 72 random Singaporeans as a form of a primary survey to determine if Singaporeans have any prior knowledge on plastic waste management and to showcase the importance of this proposal. Singaporeans are one of the main stakeholders as they play a part in producing plastic waste. Furthermore, there is a need to spread awareness of the importance of plastic waste.
This is crucial as the team wants to know if the surveyees have similar views of plastic waste and the results of the survey would help the team to convince the National Environment Agency (NEA) and Building and Construction Authority (BCA) that Singaporeans are calling for improvement in recycling efforts and that our proposed solution could be potential way to recycle plastic.
5.2. Secondary Research
The main source of secondary research is NEA and BCA. An online journal published by Zainab Z. Ismail benefits the proposal as a reliable source. This journal provides credible studies that prove that “reusing waste plastic as a sand-substitution aggregate in concrete gives a good approach to reduce the cost of the materials are problems posed by plastics” (Zainab, 2008)
6. Conclusion
In conclusion, plastic is the top contributor to the rapid influx of our landfills having the lowest recycling percentage, with the adoption of converting waste plastic into construction material would help increase Singapore’s plastic waste recycling rate and reduce the amount of plastic from being burnt. The conversion will then reduce the effect of plastic occupying the majority of the landfill space, as plastic requires a long period of time to disintegrate.
By incorporating plastic into construction materials, we are able to discover enhanced materials properties for complex construction purposes. New and improved construction materials with plastic incorporated could deliver a better result as compared to the original materials, as plastic have a different physical property as compared to traditional materials. This could help construction companies in Singapore to explore more possible new construction methods with the new sustainable products produced.
As the cost of sorting plastics are very high, Singaporeans can play a huge part by sorting their recyclables and disposing it into separate bins instead of the ‘blue recycling bins’ as a single-stream recycling. By having separate bins, the amount of effort and time using to sort the waste rubbish would be saved.
We hope that BCA is able to provide adequate aid in terms of research and development findings, which allows us to test and identify any flaws to be rectified. This would allow us to adopt the usage of the recycled plastic construction materials in the near future and allow us to discover further benefits of this recycled plastic and put it into good use.
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