2024 – RCC Mix Design Trials for Burdekin Falls Dam Raising and Improvement Project

Stephen Tatro, James Hinds, Mehdi Afshar

The use of Roller Compacted Concrete (RCC) in dam construction as well as improvement/raising projects is an ever-evolving process. The implementation of RCC as part of the Burdekin Falls Dam Raising and Improvement Project combines tried-and-true technology with relatively new technology that has few examples of use. This paper documents the issues considered and the processes formulated to implement this soon-to-be one-of-a-kind material and placement. The RCC developed for this project has never been implemented in such a massive application. Its usefulness to the industry could be significant to the dam rehabilitation sector and may demonstrate significant economy over previously available options. Furthermore, it may provide a basis to rethink facing options used for new RCC dams. The relatively small placements required to raise and improve Burdekin Falls Dam are very slow when using conventional vibrated concrete (CVC) and somewhat constricted in available placing area required for RCC. Coupled with a formed spillway slope and special bonding requirements to the existing dam, RCC placements become very difficult. However, the production rates of RCC overshadow those of CVC. The solution is to use an RCC that can be roller compacted in most of the cross-section and internally vibrated at the perimeter. Also known as immersion vibrated roller compacted concrete (IVRCC), this technology combines the higher production rates of RCC and the intricate internal vibration useful for CVC. The challenge is to formulate a mixture that can do both and achieve beneficial physical properties. The co-authors have designed thousands of RCC mixtures for more than 75 RCC dams as well as other RCC structures. IVRCC is not a new idea; however, it has never gained traction as a viable alternative to other RCC treatments. This paper is a case study of the process of developing appropriate RCC mixtures for Burdekin Falls Dam. This may be the first use of this technology in Australia and possibly one of the largest implementations in the world. RCC mixtures have been developed with appropriate aggregate ratios and workability levels deemed suitable to support vibratory rollers, yet sufficiently workable to allow consolidation by internal vibration. Test blocks were constructed to demonstrate the capability and range of small-scale internal vibration. The next step will be to stage a full-scale demonstration where appropriately sized equipment will show the RCC to be suitable for both compaction and consolidation.