Nam Theun 1: New achievements for RCC dams

The Nam Theun 1 hydro project in Laos includes a 187 m-high curved RCC gravity dam, constructed between January 2019 and February 2022, mostly under restrictions caused by the COVID 19 pandemic. Despite this, peak volumes of 16 462 m3 and 361 333 m3 of RCC were placed in one day and one month, respectively, by the contractor, and more than 300 000 m3 of RCC was placed in six consecutive months. More than 300 000 m3/month of RCC was placed on two occasions. A total of 20 RCC mix designs were used in the dam, including cement and flyash provided by three suppliers for each material, and from three countries (Laos, Vietnam and Thailand). Challenges and major achievements of the project are described here.