A research funded by Qatar National Research Fund (QNRF), a member of Qatar Foundation (QF), has resulted in stronger and more sustainable roads in the country with advanced national standards for pavement construction.
“Road quality is driven by specifications - if you specify old technology, you get lower quality. Similarly, if you update your specifications and technologies, the road construction industry steps up its game to deliver to high specifications,” said Dr Eyad Masad, professor at Texas A&M University at Qatar, who led the research.
Dr Masad collaborated with the Public Works Authority (Ashghal) to launch efforts to improve road specifications that supported the ambitious road plans, notes an article on QF website. He was awarded the first QNRF research project in the area of road construction and has since been awarded several QNRF grants for projects in the same area.
To make the roads strong, there was the need for rethinking on the materials used for making them and the design of the layers of the roads. Dr Masad’s group started their research by characterising the properties of the materials that were then being used for road construction in Qatar.
“This helped us understand the strengths and weaknesses of the materials, particular in a country like Qatar where they face the challenge of extreme heat,” Dr Masad said.
With most roads in Qatar being constructed using asphalt mixtures, the group’s primary focus was on improving the strength of asphalt.
“Instead of using the asphalt that comes from the refinery, which would not sustain Qatar’s temperatures and road truck loads, we worked on coming up with modification of this asphalt by adding polymers to it,” explained Dr Masad.
Adding polymers to asphalt is a commonly used practice globally but there was still a need to adopt this technology for Qatar’s conditions; the group researched which type of polymer, and in what quantity, would be best for use in Qatar’s environment and expected road load.
Dr Masad said: “Polymer modified asphalt has improved strength, resistance to fatigue and deformation. In simple terms, it significantly increases the lifetime of roads and reduces the need for costly maintenance.”
Another aspect was how to recycle old roads and use them in the construction of new roads. Typically, old roads are crushed and sent to landfills.
“To avoid this or at least minimise it, our research supported efforts on developing standards for incorporating recycled materials into the construction of new roads,” Dr Masad said.
“Some roads in Qatar now use 20% recycled materials, and we expect this number to increase with time as we learn how to better incorporate recycled materials.”
Other locally recycled materials the group worked on incorporating in the construction of new roads include crumb rubber — recycled rubber produced from automotive, scrap truck tires, and recycled plastics.
“Use of 20% recycled asphalt reduces the total cost of asphalt mixtures by about 15%, and the use of crumb rubber asphalt can reduce the life cycle cost of asphalt layers by about 30% because of reduction in thickness and improved quality,” he pointed out.
The biggest contribution in the area of environment, health, and safety made by the group was introduction of a technology that uses Warm Mix Asphalt (WMA).
“Previous standards in the country used Hot Mix Asphalt in which the asphalt material used on the roads is very hot, the temperature during construction being about 160C,” he said. “With WMA, this temperature can be reduced by about 20C.”
The lower mixing and construction temperatures mean reduced energy and fuel consumption. More importantly, it minimises toxic fume emissions and creates cooler and safer working conditions for the workers.
For each 12C reduction in temperature, the fumes released are reduced by around 50% leading to a temperature reduction of 20C with fumes being reduced by about 70%.
“Ashghal was very supportive throughout this journey. It was their drive to deliver the best for Qatar and their willingness to work with us that enabled the transfer of our research from the lab to the real world,” Dr Masad added.