Traffic use and weather conditions determine the state of roads anywhere – be it the cold winters of Michigan or the hot seasons of Pakistan. The difference between the two in managing the adverse effects on roads lies in Michigan’s maintenance culture and technological edge which Pakistan stands to gain from.

In a report just submitted to the National Academy of Sciences, MSU researcher Gilbert Baladi explained how asphalt recycling – a well tested method in Michigan – can transform the road management techniques in Pakistan.

“A promising approach that has evolved in recent years has been that of the roadway recovery concept, better known as recycling,” said Baladi, a professor of civil and environmental engineering and research team leader. “Asphalt recycling involves the reuse of existing roadway materials in the reconstruction and/or rehabilitation of pavements.”

The materials present in old asphalt pavements have residual value even when the pavements have reached the end of their service lives. Recycling recognizes the value of those existing aggregate and asphalt resources through a process known as reclaimed asphalt pavements. Mixtures containing these reclaimed materials perform as well as virgin mixtures.

“Old asphalt pavements can be milled up and recycled into new mixtures for the same project or stockpiled for later use. The value attributed to the reclaimed asphalt should take into account the cost of transportation, handling, stockpiling, processing and testing,” said Syed Haider, a postdoctoral candidate and Baladi’s research collaborator.

Haider said the continued use of recycled asphalt in pavement rehabilitation is desired because: it has performed well in the past if properly accounted for in the mix design, it’s economical and can help to offset the increased initial costs of construction materials known as binder and aggregates, it conserves natural resources, and in fact, not reusing it could cause disposal problems and increased costs.

In Pakistan, road transport is the most common transportation mode, which is experiencing tremendous traffic growth. The high rate of pavement deterioration, the increasing traffic demand, and the limited resources to maintain and fix the road network represent a major problem facing the highway authorities.

Baladi said it is estimated that maintenance of the existing Pakistani highways will be a massive task, given the limited resources available for infrastructure needs. “Long-term asset management analyses indicate that restoration of the existing road network conditions to an acceptable level requires annual expenditures of approximately $100 million or 6 billion Pakistani rupees. Such costs could be decreased if a comprehensive pavement preservation program is designed and implemented.”

The experience in Michigan shows that recycling asphalt pavement makes both environmental and economic sense. Above all, “developing a recycling methodology for Pakistan will not only contribute to educational and research growth, it also will help in efficient utilization of scarce public resources,” Baladi said.

Like Michigan, climatic conditions in Pakistan, including temperature and moisture variations can sometimes go to extremes and ultimately affect the performance and the service life of the pavement structure.

“Owing to its varying geography, Pakistan has temperatures that vary from subfreezing in the permanent snowline area to more than 100 F in the Indus plains. Similarly, rainfall has a variable spread throughout the country with very high records in mountainous areas in the north to far less measures in desert areas in the south,” Haider said.

The study findings emanate from the work of a joint research team from MSU and the Pakistani Institute of Transportation through a grant from the Pakistan-United States Science and Technology Cooperative Program.