THIRUVANANTHAPURAM: Though Chief Minister Oommen Chandy says rubber bitumen will be used for road tarring, PWD engineers assert that it will not be economically viable as the state is going through a lean financial phase. Rubberised bitumen will cost Rs 50,000 - Rs 60,000 per metric tonne and Rs 10,000 - Rs 15,000 more than for normal tarring. Also, 60,000 to 75,000 metric tonnes of rubberised bitumen will be required per year, entailing a whopping Rs 7,000 crore.
Most of the non-rubberised roads are damaged within months of tarring, especially during the rainy season. There are three types of bitumen – bitumen 60-70, bitumen 80-100 and natural rubber-modified bitumen (NRMB). Usually, 50-100 ml of bituminous macadam (BM) is laid as the first layer and 25 ml thickness of bituminous concrete or rubberised bitumen as the second layer, say PWD engineers. For decades, the PWD has been relying on chipping carpet with one to one-and-a-half cm thickness when it should be two cm.
“The CM’s plan to rubberise the roads is a good effort. But at first, the foundation of the road has to be strengthened or else laying rubberised bitumen will only further damage the road. Moreover, Kerala can brand its own rubber. But it may not be feasible as the plan fund allocated for the PWD is less than Rs 100 crore,” said a PWD official. According to PWD engineers, when the state has 35,000 km of roads and if 20 percent of it has to be rubberised, it requires Rs 1 crore to resurface a km making it a whopping '7,000 crore. The PWD also requires another Rs 750 crore for the annual maintenance of roads.
