ABSTRACT
Porce III hydroelectric development is currently under design and it includes a 146 m high RCC dam, which by the time of construction would be the fourth RCC dam built in Colombia and the second in the hydrological basin of Porce river. The dam will be located in a hot and rainy region of the northwestern part of the country. In the first part of this document, a discussion about the foundation requirements is presented. In the second part, a description of the most outstanding technical design features is given; among these features, the mix design includes moderate cementitious contents and no cooling of aggregates. Additives have been considered not only to delay the initial setting time, but also to improve strength of the RCC. Identification of setting times of RCC by ultrasonic energy devices is specified. To control cracking, transversal contraction joints have been designed every 20 m. To improve permeability and strength of the RCC mass, bedding mix spread over the dam area has been specified. The design involves the most recently developed and successfully proved experiences to prevent leakage that consist of a combination of grouted enriched RCC and a PVC membrane. In the third part, some special construction procedures are presented. In order to reduce cost of the bedding mix and to improve placing rates, technical specifications allow the use of the horizontally sloped layered construction. Transportation of RCC by vacuum chutes between the mixing plant and the dam is also considered. Most of the aspects presented in this paper are based on recently developed experiences acquired during construction of the last two RCC dams built in Colombia: Porce II and Miel I.
