Proposal Draft 1

 1.0  Introduction 

This report has been developed in response to the request for proposals on developing solutions for engineering problems. This report aims at determining the suitability of using waste plastic materials as modifiers in bituminous road pavement construction.

1.1 Background information 

1.1.1 Plastic Waste 

Plastic is a very versatile material. Due to the industrial revolution, and its large scale production plastic seemed to be a cheaper and effective raw material. Today, every vital sector of the economy starting from agriculture to packaging, automobile, electronics, building construction, communication sector has been virtually revolutionized by the application of plastic. Plastic is a non-biodegradable material and researchers found that the material can remain on earth for 4500 years without degradation.

The growth in various types of industries together with population growth has resulted in an enormous increase in production of various types of waste material world over. The creation and disposal of non-biodegradable waste material have been posing problems in the developed countries. Plastic is everywhere in today’s lifestyle. Using this non-biodegradable product is growing rapidly and creating the problem at its disposal. In a small country like Singapore with a population of over 5.6 million people, Singapore is one of the most densely populated countries in the world. Singapore is a developed country, with the 7th highest GDP per capita, where plastic bags and other single-use plastics have become cheaply and widely available. For more than three decades, retailers and eateries have offered plastic bags, containers and disposable cutlery at no extra charge to their customers, making single-use plastic part and parcel of the fast-paced urban Singapore lifestyle. In a paper released by the Singapore Environment Council in 2011, it was estimated that Singapore uses three billion plastic bags for an average of just 12 minutes.

Figure 2: NEA Waste Statistic and Overall Recycling (NEA, 2018)

1.1.2 Bitumen

Pavement surfaces around the world have a long history of using bitumen as a binder in asphalt mixtures (Shell 2015). Bitumen itself is a by-product of crude oil refining for the production of petroleum gas, petroleum fuels, diesel fuel and lubricating oils. The residue from the second distillation of crude oil includes bitumen, that is then separated and processed for sale in the road, airport and port pavement construction industry, as well as the production of roof shingles and other products.

Traditionally, asphalt production used unmodified bitumen, usually graded according to either its viscosity or resistance to load penetration at certain temperatures. However, as the required engineering properties of asphalt mixtures increased over time, polymers, acids and other additives were incorporated to increase the resistance of asphalt mixtures to high temperature deformation, low temperature cracking and moisture damage (Shell 2015).

Bitumen is a black, thermoplastic hydrocarbon material derived from the processing of crude oil. Heavier grade cut backs, rapid setting emulsions or heavier grade tars may also be used. The grade of basic bitumen is altered either by controlled refining or by mixing with diesel oil or other oils. 

1.1.3 Use of plastic in road pavements

The need for engineering is to find innovative solutions to tackle plastic waste. If these materials can be suitably utilized in road construction, the pollution and disposal problems may be partly reduced. One opportunity is to partially replace high-cost bituminous binder with low-cost recycled plastic in asphalt mixtures. This synthesis combines the various research efforts to understand the effects of two commercially available recycled plastics, known as MR6 and MR10, on bituminous binders and in asphalt mixtures. The waste polymer-bitumen blend was prepared in various proportions and the rheological properties determined in the laboratory. This innovative technology will be a boon for Singapore’s climate. It’s economical and eco-friendly. Many countries have now reported the use of recycled plastic in asphalt mixture production, either as an aggregate extender, a bitumen extender, or a binder modifier. For example, a New Zealand asphalt contractor added shredded engine oil containers to asphalt at Christchurch Airport and an independent asphalt producer includes recycled plastic as bitumen extended in every ton of asphalt produced. Moreover, Janshedpur (India) reported reducing bitumen usage by 7% by mixing shredded recycled plastic during asphalt production. It is clear that there is great interest in the use of recycled plastic in bituminous binders and asphalt mixtures. 

1.4 Problem Statement

Plastic has always been a global issue in terms of its waste and disposal. Main methods of disposal include burning and landfilling, which does not solve the problem, creating larger issues such as soil and air pollution. 

1.5 Purpose Statement

The purpose of this report is to propose to LTA (Land Transport Authority) the viability of incorporating plastic waste for the paving of roads, which will result in reducing the impact on the environment caused by the abundance of plastic in Singapore.

2 Proposed Solution

The team proposes a solution to incorporate plastic waste into the wearing layer of a flexible pavement. This layer consists of bitumen, which is the material that we are proposing to substitute. As the flexible pavement consists of a high percentage of bitumen, we are proposing to substitute 6-8% of it in the bituminous mix.