Thiruvananthapuram, India - The Kerala government has asked the Cochin Refinery to see that they produce more natural rubber modified bitumen (NRBM), Chief Minister Oommen Chandy said. NRBM is prepared by adding 5 percent natural rubber latex to the bitumen. The price of one metric ton NRBM is around Rs.55,000, while ordinary bitumen used for road surfacing comes to around Rs.39,000 per metric ton.