Question

For underwater concreting, tremie pipes are normally used with aid of hoppers. From time to time tubes are put in inside the hoppers and with reasons?

Answer

At place of concrete by tremie pipes, hoppers are connected to their peak for receiving newly placed concrete. Though, air might be trapped inside tremie pipes if there is rapid feeding of fresh concrete. To release trapped air inside tremie pipes, hoses are also called ventilation tubes are inserted and lowered down through hoppers.