September 7, 2009

Plastic Roads ahead

A chemistry professor from Tamil Nadu has discovered that a marriage of convenience between hot bitumen and molten plastic waste could be the way towards what Lalu Prasad had once dreamt for Bihar’s roads.

R. Vasudevan’s finding, which promises to solve the twin problems of battered roads and plastic waste, has received official recognition, with the Union rural development ministry issuing guidelines for laying rural roads using plastic waste.

Civic bodies in Tamil Nadu and the state’s highway department have already laid more than 750km of plastic roads and are adding more based on the process developed by Vasudevan, head of chemistry at Thiagaraja Engineering College, Madurai.

“It’s a simple procedure where plastic waste is mixed with hot bitumen before it is laid. Since plastic waste like cups, carry bags, etc, are heated only up to 170°C, they form a molten paste and get mixed with the bitumen,” said Vasudevan, who has given the patent of the process to the college.

He added: “Since the waste is not incinerated, which happens at 690°C, no toxic gases are released. As only non-chloride polymer waste is used, chlorine seepage into the ground is also avoided.”

Adding plastic reinforces a road in three ways. It increases the road’s load-bearing capacity, makes it more resistant to heat especially during summers, and prevents rainwater from seeping down. The third factor ensures durability, since water is the main enemy of bitumen-based roads.

“The life of the road will be prolonged three to four times provided there are no cuts and patchwork after it is laid,” Vasudevan said.

Performance studies on the roads built with plastic waste in Tamil Nadu indicate “satisfactory performance with good skid resistance, good texture value, stronger and less amount of progressive unevenness over a period of time”, say the guidelines issued by the National Rural Roads Development Agency, an arm of the Union rural development ministry.

The ministry recommends the use of polyfilms with thickness up to 60 microns, hard and soft foams and laminated polymer with thickness up to 60 microns. However, polyvinyl chloride sheets (flex sheets) should not be used. The process of coating the aggregate (tar and granite mixture) with molten (waste) plastic does not require machinery.

Modifying bitumen with shredded plastic waste raises the cost by Rs 2,500 per tonne, but this is offset by the need for less bitumen, better performance and environmental conservation, the guidelines say. They even ask local bodies to contact Vasudevan (0452-2482240) for further advice.

Vasudevan said the local bodies could initially source the plastic waste from their own dumps, since a 10x10-metre road needs just 1.7kg of plastic. Two lakh tonnes of plastic items are sold every month in Tamil Nadu alone, of which 40 per cent is recycled and 10 per cent gets into garbage.
Source- The Telegraph
Post a Comment