Hyderabad: Contractors are replacing cement with fly ash and river sand with Robo sand in the concrete mix used to lay roads. This is resulting in cement roads breaking up. Even roads laid during the 100-day action plan have been damaged after a few spells of heavy rain in July. The GHMC quality control wing, instead of tying up with ready-mix concrete plants to ensure the supply of quality material, is now permitting contractors to purchase materials on their own. This leaves scope for compromise in quality. Most of the internal roads are made of cement.
Prof. Lakshmana Rao, head of the JNTU’s civil engineering department, said cement roads should have a non-penetrating layer so that rainwater does not seep in. The ready-mix concrete for cement roads includes cement, sand and aggregate (different types of rock material). “Fly ash, if used, can give cost effectiveness but will not strengthen roads against loads. This leads to breaking of roads,” he said.
An RMC plant owner said fly ash, which is left over after coal is burnt at thermal power plants, costs 70-90 paise per kg, against Rs 6 for cement. “But fly ash does not give strength,” he said. Robo sand or crushed rock is less expensive than river sand. “If Robo sand is used, it halves the life of the road. The GHMC should tie up with the RMC plants and release the bills directly so that quality material is supplied,” he said.
The city’s main roads are bitumen-topped. Prof. Lakshmana Rao said that the BT roads have five layers — sub-grade, sub-base 1, sub-base 2, base course and wearing course. “The bottom layer or sub-grade is important for road strength. Most contractors just lay the base course and wearing course (the two top layers.). Because of this, the road gets damaged quickly, and potholes are formed,” he said.
