ISLAMABAD: As the United Nations roadmap outlines solutions to cut global plastic pollution, new options are being explored to use plastic waste as partial substitute for raw material as a bitumen modifier in road construction.

A report of the World Bank, “Plastic Waste in Road Construction: A Path Worth Paving?” says the upcoming international, legally binding treaty to reduce plastic pollution calls for a full life cycle approach to reduce plastic pollution, incorporating both upstream and downstream measures.

The use of plastic waste in road construction is a downstream measure to utilise plastic waste as an input material and further upstream measures to reduce plastic waste are needed, the report says.

The use of plastic waste as a bitumen modifier in roads, referred to here as plastic roads, has emerged as an innovation which uses plastic waste as an input material. The report found that many companies are starting to implement or pilot this technology worldwide though key gaps in engineering performance, such as cracking resistance, remain.

Pakistan recently built its first plastic road in Islamabad

Since the use of plastic waste in road construction targets plastic waste after the use and maintenance stages, plastic roads are considered a downstream measure.

Authors of the report found that the use of plastic waste in road construction is a viable option for the application of plastic waste that also protects environmental and human health.

The report found 132 total plastic roads project worldwide. Recently, Pakistan has also constructed its first plastic road in Islamabad. The report estimates that 58 per cent of plastic roads projects surveyed were in planning, pilot, or construction phases while 37 per cent were already constructed and in use.

The Capital Development Authority’s member of engineering, when contacted, told Dawn that over a kilometre plastic road had been recently constructed from Ayub Chowk to Margalla in collaboration with a private company.

The report says that further research is needed to fill major gaps in our knowledge base of plastic roads. Opportunities for close monitoring and further research may be found in countries that are already piloting or using plastic roads.

Given the large amounts of plastic waste produced globally, entrepreneurs, innovators and researchers are discovering new ways of utilising plastic waste. The report aims to provide an overview on the use of plastic waste in road construction using the dry process in South Asia, in comparison to conventional roads.

The report says that plastic roads are an emerging technology. The dry process primarily faces quality control issues, such as uneven distribution of plastic waste within the asphalt mix. This results in operational issues for the industry and constraints in mainstreaming the technology.

Similarly, additional and upgraded equipment would be needed to incorporate plastic waste into asphalt at the plant. Since this technology is relatively new and most countries lack standardised guidelines, long-term outcomes remain unclear and further pilot and research projects are needed, it says.

According to the report, overall, there is currently high uncertainty in the field regarding the performance of plastic roads.

A few studies show that the use of plastic waste in road construction may reduce road cracking resistance. Long-term performance of plastic roads under a range of environmental conditions, including flooding, remains unclear. Without this certainty, it will be difficult to ensure that plastic roads will not require more maintenance than conventional roads.

Published in Dawn, May 29th, 2023