MUMBAI: Transport minister Nitin Gadkari on Thursday said all new road projects of the Centre will use concrete."All the new roads which we will be constructing will be of concrete," Gadkari told reporters.Against the prevalent rate of Rs 350 per bag of cement, Gadkari said the ministry had found a supplier near Mumbai ready to deliver at Rs 120 per bag, excluding taxes and transport, and advised the Maharashtra government and local bodies to avail of it.The target of increasing the speed of highway construction to 30 km a day will be achieved within 18 months against the 24 months estimated earlier as work on 95 per cent of 190-odd road projects, stuck in the past, has started, he added.Gadkari also advocated the use of technologies such as the one where a by-product of oil is used for road laying and added that the Centre had recently issued a notification to this effect.Besides, the minister said the Mumbai-Goa National Highway (NH-17) will be converted into a four-lane concrete road soon.About the work on NH-17, Gadkari said the government had started work of 15 bridges with priority but there were problems related to land acquisition, for which he had sought the Maharashtra government's help.In future, no work will be started unless 80 per cent of the land acquisition is over, he added.Asked about the Karnala Bird Sanctuary stretch in Raigad district along the NH-17, Gadkari said an NGO had moved the court seeking a stay on the work citing environmental degradation but a solution would be found.