Seite - 1510 - in Book of Full Papers - Symposium Hydro Engineering

Fig. 2 Conveyor systems for transporting the RCC (Javeh Dam-Iran) RCC Placement Temperature: The placement temperature of the RCC is an important consideration relative to the potential for surface and mass gradient cracking in the gravity dam construction. In hot weather, for reducing of RCC temperature, aggregate cooling shall be accomplished by several methods. These methods include mining and processing the aggregate in colder seasons, shading stockpiles from direct sunlight and evaporative cooling of aggregates in the stockpiles. Some reduction in the placement temperature of the RCC can be achieved by cooling the mix water. Under cold weather, heating of mixing water and protection of RCC exposed surface shall be considered. Under the most extreme weather conditions, the RCC placement tasks are stopped. Segregation: Segregation of RCC during transport and placement shall be controlled by employing means and methods similar to those used in transporting and placing conventional concrete. For this propose the gradation of aggregate, time of mixing in batching plant, transporting system of RCC and concreting equipment should be controlled. Figure 3 shows segregation of RCC. Fig. 3 Segregation of RCC and effect of segregation on lift surface Timing: Time limitations are commonly prescribed to keep the RCC from setting before final spreading and compaction. In RCC dams the following time limits for handling, transporting and compacting the RCC: • Maximum time from plant to spreading on the fill is 45 minutes; • Compaction starts within 15 minutes of spreading; 1510