Alternative Dam Construction Techniques
Water resources management in Georgia has taken on new importance over the last few years because of a series of years where below-normal rainfall has occurred. Georgia on the average receives approximately 49 inches of rainfall a year (NOAA, 1988). Thus the problem is not one of quantity but of collection and storage. Man-made reservoirs are an important source for water supply but are becoming more difficult to site because of environmental regulations. Today's planners and designers must be innovative in their approach with designing dams and the operation of the reservoirs. During the last decade a relatively new technology has been adapted for use in new gravity dam construction and for the rehabilitation of existing dams and spillways. This technology, called roller compacted concrete (RCC), although still in its infancy, is growing rapidly. Because RCC is a relatively new technique in dam construction, its technology is currently being developed and tested by various private and government organizations. RCC is defined as a no-slump consistency concrete that is placed in thin horizontal lifts and compacted by vibratory rollers. RCC should not be confused with soil cement or cement-treated graded aggregate base. Although similar, RCC, as used in dam construction, must have engineering properties that are very similar to cast-in-place concrete after it has set and cured. Major differences still exist among designers as to the best methods for placing the material, treatment of cold joints, mix consistency and proportions. Efforts are underway to develop standards, particularly test procedures, for determining mix density and consistency. As of the date of this paper, each designer of an RCC dam project develops his own technique, drawing from the successful experiences of previous projects.